Mars Science Laboratory Launch

Press Kit/NOVEMBER 2011
Media Contacts

Dwayne Brown NASA’s Mars 202-358-1726

Trent Perrotto Program 202-358-0321

Headquarters dwayne.c.brown@nasa.gov 

Washington trent.j.perrotto@nasa.gov

Guy Webster Mars Science Laboratory 818-354-5011

Jet Propulsion Laboratory Mission guy.webster@jpl.nasa.gov

Pasadena, Calif.

George Diller Launch 321-867-2468

Kennedy Space Center, Fla. george.h.diller@nasa.gov

Jessica Rye Launch Vehicle 321-730-5646

United Launch Alliance and Operations jessica.f.rye@ulalaunch.com

Cape Canaveral, Fla.

Science Payload Investigations

Alpha Particle X-ray Spectrometer: Ruth Ann Chicoine, Canadian Space Agency, Saint-Hubert, Québec, 

Canada; 450-926-4451; ruthann.chicoine@asc-csa.gc.ca 

Chemistry and Camera: Nancy Ambrosiano, Los Alamos National Laboratory, Los Alamos, N.M.; 

505-667-0471; nwa@lanl.gov 

Chemistry and Mineralogy: Cathy Weselby, NASA Ames Research Center, Moffett Field, Calif.; 

650-604-4789; cathy.weselby@nasa.gov 

Dynamic Albedo of Neutrons: Igor Mitrofanov, Space Research Institute, Moscow, Russia; 

011-7-495-333-3489; imitrofa@space.ru 

Mars Descent Imager, Mars Hand Lens Imager, Mast Camera: Michael Ravine, Malin Space Science 

Systems, San Diego; 858-552-2650 extension 591; ravine@msss.com 

Radiation Assessment Detector: Donald Hassler, Southwest Research Institute; Boulder, Colo.; 

303-546-0683; hassler@boulder.swri.edu 

Rover Environmental Monitoring Station: Luis Cuesta, Centro de Astrobiología, Madrid, Spain; 

011-34-620-265557; cuestacl@cab.inta-csic.es 

Sample Analysis at Mars: Nancy Neal Jones, NASA Goddard Space Flight Center, Greenbelt, Md.; 

301-286-0039; nancy.n.jones@nasa.gov 

 

Engineering Investigation

MSL Entry, Descent and Landing Instrument Suite: Kathy Barnstorff, NASA Langley Research Center, 

Hampton, Va.; 757-864-9886; kathy.barnstorff@nasa.gov 
Contents

Media Services Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Quick Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Mars at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Mars Science Laboratory Investigations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Mission Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Comparing Two Mars Rover Projects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Spacecraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Mars Science Laboratory Landing Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Recent, Current and Upcoming Missions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Mars Science: A Story of Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Historical Mars Missions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Program/Project Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Mars Science Laboratory Launch 5 Press Kit

Media Services Information

NASA Television Transmission

The NASA TV Media Channel is available on an MPEG2 digital C-band signal accessed via satellite AMC-6, 

at 72 degrees west longitude, transponder 17C, 4040 

MHz, vertical polarization. In Alaska and Hawaii, it’s 

available on AMC-7 at 137 degrees west longitude, 

transponder 18C, at 4060 MHz, horizontal polarization. 

A Digital Video Broadcast-compliant Integrated Receiver 

Decoder is required for reception. For digital downlink 

information for NASA TV’s Media Channel, access to 

NASA TV’s Public Channel on the Web and a schedule 

of programming for Mars Science Laboratory activities, 

visit http://www.nasa.gov/ntv.

Media Credentialing

News media representatives who would like to cover 

the launch in person must be accredited through the 

NASA Kennedy Space Center newsroom. Journalists 

may contact the newsroom at 321-867-2468 for more 

information.

Briefings

An overview of the mission will be presented in a news 

briefing broadcast on NASA TV and on http://www.

ustream.tv/nasajpl, originating from NASA Headquarters 

in Washington, at 1 p.m. EST on Nov. 10, 2011. A prelaunch briefing at Kennedy Space Center is scheduled 

at 1 p.m. EST on Nov. 22, 2011, followed by a briefing 

about the mission’s science goals and capabilities. A 

post-launch briefing at KSC will begin approximately 

two to three hours after launch. Supplemental briefings 

at KSC will present information about Mars, at 1 p.m. 

EST on Nov. 21; about astrobiology, at 11 a.m. EST

on Nov. 22; and about how excitement about Mars is 

used in education and other fields, at 1 p.m. EST on 

Nov. 23. All of these MSL and supplemental briefings 

will be carried on NASA TV and on http://www.ustream.tv/nasajpl . 

Specific information about upcoming briefings, as they 

are scheduled, will be kept current on the Internet at 

http://www.nasa.gov/msl .

Live Feed

A live feed of video during key launch activities from 

the mission control room at Cape Canaveral Air Force 

Station will be carried on NASA TV and on http://

www.ustream.tv/nasajpl between about 7:30 a.m. and 

11:30 a.m. EST on Nov. 25.

Internet Information

Information about NASA’s Mars Science Laboratory 

mission, including an electronic copy of this press kit, 

press releases, status reports and images, is available 

at http://www.nasa.gov/msl and http://marsprogram.

jpl.nasa.gov/msl . Frequent updates about the mission, 

together with public feedback, are available by following 

Curiosity on Twitter at http://www.twitter.com/marscuriosity and on Facebook at http://www.facebook.com/

marscuriosity . 
Mars Science Laboratory Launch 6 Press Kit

Quick Facts

Spacecraft 

Cruise vehicle dimensions (cruise stage and aeroshell 

with rover and descent stage inside): Diameter: 14 feet, 

9 inches (4.5 meters); height: 9 feet, 8 inches (3 meters)

Rover name: Curiosity

Rover dimensions: Length: 9 feet, 10 inches (3.0 meters) 

(not counting arm); width: 9 feet, 1 inch (2.8 meters); 

height at top of mast: 7 feet (2.1 meters); arm length: 

7 feet (2.1 meters); wheel diameter: 20 inches (0.5 

meter) 

Mass: 8,463 pounds (3,893 kilograms) total at launch, 

consisting of 1,982-pound (899-kilogram) rover; 

5,293-pound (2,401-kilogram) entry, descent and landing system (aeroshell plus fueled descent stage); and 

1,188-pound (539-kilogram) fueled cruise stage

Power for rover: Multi-mission radioisotope thermoelectric generator and lithium-ion batteries

Science payload: 165 pounds (75 kilograms) in 10 

instruments: Alpha Particle X-ray Spectrometer, 

Chemistry and Camera, Chemistry and Mineralogy, 

Dynamic Albedo of Neutrons, Mars Descent Imager, 

Mars Hand Lens Imager, Mast Camera, Radiation 

Assessment Detector, Rover Environmental Monitoring 

Station, and Sample Analysis at Mars

Launch Vehicle

Type: Atlas V 541

Height with payload: 191 feet (58 meters) 

Mass, fully fueled, with spacecraft on top: 1.17 million 

pounds (531,000 kilograms)

Mission

Launch period: Nov. 25 through Dec. 18, 2011

Launch windows: Launch opportunities every five minutes during daily windows 103 minutes long at the start 

of the launch period and 44 minutes long at the end of 

the launch period. First launch opportunity on Nov. 25: 

10:25 a.m. EST

Launch site: Launch Complex 41, Cape Canaveral Air 

Force Station, Fla. 

Earth–Mars distance on Nov. 25, 2011: 127 million 

miles (205 million kilometers)

Mars landing: Between 1 p.m. and 10:30 p.m. Pacific 

Daylight Time, Aug. 5, 2012. (Aug. 6, 5 a.m. to 5:30 

a.m. Universal Time; Aug. 6, 1 a.m. to 1:30 a.m., 

Eastern Daylight Time). This will be about 3 p.m. local 

time at the Mars landing site.

Landing site: 4.5 degrees south latitude, 137.4 degrees 

east longitude, inside Gale Crater 

Earth–Mars distance on Aug. 6, 2012: 154 million miles 

(248 million kilometers) 

One-way radio transit time, Mars to Earth, on Aug. 6, 

2012: 13.8 minutes

Total distance of travel, Earth to Mars: About 354 million 

miles (570 million kilometers)

Primary mission: One Martian year (98 weeks) 

Expected near-surface atmospheric temperatures at 

landing site during primary mission: minus 130 F to 32 

F (minus 90 C to zero C) 

Program

Cost: $2.5 billion, including $1.8 billlion for spacecraft 

development and science investigations and additional 

amounts for launch and operations.
Mars Science Laboratory Launch 7 Press Kit

Mars at a Glance

General

•	 One of five planets known to ancients; Mars was 

the Roman god of war, agriculture and the state

•	 Yellowish brown to reddish color; occasionally the 

third-brightest object in the night sky after the moon 

and Venus

Physical Characteristics

•	 Average diameter 4,212 miles (6,780 kilometers); 

about half the size of Earth, but twice the size of 

Earth’s moon

•	 Same land area as Earth, reminiscent of a cold, 

rocky desert

•	 Mass 1/10th of Earth’s; gravity only 38 percent as 

strong as Earth’s

•	 Density 3.9 times greater than water (compared with 

Earth’s 5.5 times greater than water)

•	 No planet-wide magnetic field detected; only localized ancient remnant fields in various regions

Orbit

•	 Fourth planet from the sun, the next beyond Earth

•	 About 1.5 times farther from the sun than Earth is

•	 Orbit elliptical; distance from sun varies from a minimum of 128.4 million miles (206.7 million kilometers) 

to a maximum of 154.8 million miles (249.2 million 

kilometers); average is 141.5 million miles (227.7 

million kilometers)

•	 Revolves around sun once every 687 Earth days

•	 Rotation period (length of day) 24 hours, 39 minutes, 35 seconds (1.027 Earth days)

•	 Poles tilted 25 degrees, creating seasons similar to 

Earth’s

Environment

•	 Atmosphere composed chiefly of carbon dioxide 

(95.3 percent), nitrogen (2.7 percent) and argon 

(1.6 percent)

•	 Surface atmospheric pressure less than 1/100th 

that of Earth’s average

•	 Surface winds of 0 to about 20 miles per hour (0 to 

about 9 meters per second), with gusts of about 

90 miles per hour (about 40 meters per second)

•	 Local, regional and global dust storms; also whirlwinds called dust devils

•	 Surface temperature averages minus 64 F (minus 

53 C); varies from minus 199 F (minus 128 C) 

during polar night to 80 F (27 C) at equator during 

midday at closest point in orbit to sun

Features

•	 Highest point is Olympus Mons, a huge shield volcano about 16 miles (26 kilometers) high and 370 

miles (600 kilometers) across; has about the same 

area as Arizona

•	 Canyon system of Valles Marineris is largest and 

deepest known in solar system; extends more than 

2,500 miles (4,000 kilometers) and has 3 to 6 miles 

(5 to 10 kilometers) relief from floors to tops of surrounding plateaus

Moons

•	 Two irregularly shaped moons, each only a few 

kilometers wide

•	 Larger moon named Phobos (“fear”); smaller is 

Deimos (“terror”), named for attributes personified 

in Greek mythology as sons of the god of war
Mars Science Laboratory Launch 8 Press Kit

Mars Science Laboratory Investigations

Mars Science Laboratory Investigations

NASA’s Mars Science Laboratory mission will study 

whether the Gale Crater area of Mars has evidence of 

past and present habitable environments. These studies will be part of a broader examination of past and 

present processes in the Martian atmosphere and on 

its surface. The research will use 10 instrument-based 

science investigations. The mission’s rover, Curiosity, 

carries the instruments for these investigations and will 

support their use by providing overland mobility, sampleacquisition capabilities, power and communications. 

The primary mission will last one Mars year (98 weeks).

The payload includes mast-mounted instruments to 

survey the surroundings and assess potential sampling 

targets from a distance; instruments on Curiosity’s 

robotic arm for close-up inspections; laboratory instruments inside the rover for analysis of samples from 

rocks, soils and atmosphere; and instruments to monitor the environment around the rover. In addition to the 

science payload, engineering sensors on the heat shield 

will gather information about Mars’ atmosphere and the 

spacecraft’s performance during its descent through the 

atmosphere.

To make best use of the rover’s science capabilities, a 

diverse international team of scientists and engineers will 

make daily decisions about the rover’s activities for the 

following day. Even if the rover’s technology all performs 

flawlessly, some types of evidence the mission will seek 

about past environments may not have persisted in the 

rock record. While the possibility that life might have 

existed on Mars provokes great interest, a finding that 

conditions did not favor life would also pay off with valuable insight about differences and similarities between 

early Mars and early Earth.

Habitability

The mission will assess whether the area Curiosity explores has ever been a potential habitat for Martian life. 

Whether life has existed on Mars is an open question 

that this mission, by itself, is not designed to answer. 

Curiosity does not carry experiments to detect active 

processes that would signify present-day biological 

metabolism, nor does it have the ability to image microorganisms or their fossil equivalents. However, if this 

mission finds that the field site in Gale Crater has had 

conditions favorable for habitability and for preserving 

evidence about life, those findings can shape future 

missions that would bring samples back to Earth for 

life-detection tests or for missions that carry advanced 

life-detection experiments to Mars. In this sense, the 

Mars Science Laboratory is the prospecting stage in a 

step-by-step program of exploration, reconnaissance, 

prospecting and mining evidence for a definitive answer about whether life has existed on Mars. NASA’s 

Astrobiology Program has aided in development of the 

Mars Science Laboratory science payload and in studies of extreme habitats on Earth that can help in understanding possible habitats on Mars.

Three conditions considered crucial for habitability are 

liquid water, other chemical ingredients utilized by life 

and a source of energy. The Mars Science Laboratory 

mission advances the “follow the water” strategy of 

NASA Mars exploration since the mid-1990s to a 

strategy of determining the best settings for seeking an 

answer to whether Mars ever supported life.

Every environment on Earth where there is liquid water 

sustains microbial life. For most of Earth’s history, the 

only life forms on this planet were microorganisms, or 

microbes. Microbes still make up most of the living matter on Earth. Scientists who specialize in the search for 

life on other worlds expect that any life on Mars, if it has 

existed at all, has been microbial.

Curiosity will land in a region where this key item on the 

checklist of life’s requirements has already been determined: It was wet. Observations from Mars orbit during 

five years of assessing candidate landing sites have 

made these areas some of the most intensely studied 

places on Mars. Researchers have used NASA’s Mars 

Reconnaissance Orbiter to map the area’s mineralogy, 

finding exposures of clay minerals. Clays, other phyllosilicates and sulfates form under conditions with adequate 

liquid water in a life-supporting, medium range between 

very acidic and very alkaline.

Curiosity will inventory other basic ingredients for life, 

seek additional evidence about water and investigate 

how conditions in the area have changed over time. 

The wet environment in which the clay minerals formed 
Mars Science Laboratory Launch 9 Press Kit

is long gone, probably occurring more than 3 billion 

years ago. Examining the geological context for those 

minerals, such as the minerals in younger rock layers, 

could advance understanding of habitat change to drier 

conditions. The rover can also check for traces of water 

still bound into the mineral structure of rocks at and near 

the surface.

Carbon-containing compounds called organic molecules are an important class of ingredients for life that 

Curiosity can detect and inventory. This capability adds 

a trailblazing “follow the carbon” aspect to the Mars 

Science Laboratory, as part of the sequel to the “follow 

the water” theme.

Organic molecules contain one or more carbon atoms 

bound to hydrogen and, in many cases, additional elements. They can exist without life, but life as we know 

it cannot exist without them, so their presence would 

be an important plus for habitability. If Curiosity detects 

complex organics that are important to life on Earth, 

such as amino acids, these might be of biological origin, 

but also could come from non-biological sources, such 

as carbonaceous meteorites delivered to the surface of 

the planet. 

Curiosity will also check for other chemical elements 

important for life, such as nitrogen, phosphorus, sulfur 

and oxygen. 

The rover will definitively identify minerals, which provide 

a lasting record of the temperatures, pressures and 

chemistry present when the minerals were formed or 

altered. Researchers will add that information to observations about geological context, such as the patterns 

and processes of sedimentary rock accumulation, to 

chart a chronology of how the area’s environments have 

changed over time. Energy for life on Mars could come 

from sunlight, heat or mixtures of chemicals (food) with 

an energy gradient that could be exploited by biological 

metabolism. The information Curiosity collects about 

minerals and about the area’s modern environment will 

be analyzed for clues about possible past and present 

energy sources for life.

Curiosity will measure the ratios of different isotopes of 

several elements. Isotopes are variants of the same element with different atomic weights. Ratios such as the 

proportion of carbon-13 to carbon-12 can provide insight into planetary processes. For example, Mars once 

had a much denser atmosphere than it does today, and 

if the loss occurred at the top of the atmosphere, that 

process would favor increased concentration of heavier 

isotopes in the retained, modern atmosphere. Such 

processes can be relevant to habitability and biology. 

Curiosity will assess isotopic ratios in methane if that 

gas is in the air around the rover. Methane is an organic 

molecule, and its carbon isotope ratio can be very 

distinctive. Observations from orbit and from Earth indicate traces of it may be present in Mars’ atmosphere. 

Isotopic ratios could hold clues about whether methane 

is being produced by microbes or by a non-biological 

process.

The mission has four primary science objectives to 

meet NASA’s overall habitability assessment goal:

•	 Assess the biological potential of at least one target 

environment by determining the nature and inventory of organic carbon compounds, searching for 

the chemical building blocks of life and identifying 

features that may record the actions of biologically 

relevant processes.

•	 Characterize the geology of the rover’s field site at 

all appropriate spatial scales by investigating the 

chemical, isotopic and mineralogical composition of 

surface and near-surface materials and interpreting 

the processes that have formed rocks and soils.

•	 Investigate planetary processes of relevance to past 

habitability (including the role of water) by assessing 

the long timescale atmospheric evolution and determining the present state, distribution and cycling 

of water and carbon dioxide.

•	 Characterize the broad spectrum of surface radiation, including galactic cosmic radiation, solar 

proton events and secondary neutrons.

Preservation and Past Environments

Some of the same environmental conditions favorable 

for life can, paradoxically, be unfavorable for preserving evidence about life. Water, oxidants and heat, all of 

which can contribute to habitability, can destroy organic 

molecules and other possible markers left by life, or 

biosignatures. 

Life has thrived on Earth for more than 3 billion years, 

but only a miniscule fraction of Earth’s past life has 

left evidence of itself in the rock record on this planet. 

Preserving evidence of life from the distant past has 

required specific, unusual conditions. On Earth, these 

windows of preservation have included situations such 

as insects encased in amber and mastodons im-
Mars Science Laboratory Launch 10 Press Kit

mersed in tar pits. Mars won’t have fossils of insects or 

mastodons; if Mars has had any life forms at all, they 

were likely microbes. Understanding what types of 

environments may have preserved evidence of microbial 

life from billions of years ago, even on Earth, is still an 

emerging field of study. 

To determine whether Mars ever supported life, a key 

step is learning where biosignatures could persist. 

Curiosity’s findings about windows of preservation will 

serve this mission’s prospector role: identifying good 

hunting grounds for possible future investigations about 

Martian life’s existence and characteristics. They can 

also guide this mission’s own course, informing decisions about where to drive and which rocks to sample 

in Curiosity’s search for organics. 

Accumulation of rock-forming sediments writes a record 

of environmental conditions and processes into those 

sedimentary rocks. The layers of the mountain inside 

Gale Crater provide a record of events arranged in 

the order in which they occurred. Researchers using 

Curiosity can look at how environments changed over 

time, possibly including transitions from habitable conditions to non-habitable conditions. Some of the clues 

are in the textures of the rocks, and Curiosity will be 

looking for distinctive rock textures. Other clues are in 

the mineral and chemical compositions. 

Some conditions and processes, such as low temperatures and rapid entrapment in the sediments, can favor 

preservation of organics and evidence about life. As 

Curiosity looks for organics by analyzing samples drilled 

from sedimentary rocks, it will be reading the history of 

past environments whether or not it finds organics.

Some minerals and other geologic materials, such as 

sulfates, phosphates, carbonates and silica, can help 

preserve biosignatures. All of these materials, forming 

under just the right balance of environmental conditions, 

have the potential to preserve fragments of organic molecules derived from microbes or carbonaceous meteorites. But not just any rock formed of suitable minerals 

will do. Most on Earth do not. Expectations for Mars are 

similar, and the chances of a discovery — even if life had 

been present — are very small. If this sounds sobering, 

it should be, but this is the only known way to prospect 

for the vestiges of life on the early Earth. 

The area at Gale Crater accessible to Curiosity as it 

drives during the mission contains rocks and soils 

that may have been originally deposited under differing conditions over a range of times. Analyzing samples 

from different points in that range could identify which, if 

any, hold organics. The rover might find that the answer 

is none. While such an answer could shrink prospects 

for finding evidence of ancient life on Mars, it would 

strengthen the contrast between early Mars and early 

Earth. The history of environmental changes on an 

Earthlike planet without life would be valuable for understanding the history of life’s interaction with Earth’s 

environment.

Modern Environment

The Mars Science Laboratory will study the current environment in its landing region as well as the records left by 

past environments. Curiosity carries a weather station, an 

instrument for monitoring natural high-energy radiation 

and an instrument that can detect soil moisture and water-containing minerals in the ground beneath the rover. 

The investigations of organics and other potential ingredients for life can analyze samples of modern-day soil for 

what nutrients would be available to soil microbes. The 

ability to check for methane in the atmosphere is a study 

of modern processes, too. Methane would break down 

and disappear from the atmosphere within a few centuries if not replenished by an active source, so its presence would be surprising. 

Selection of Curiosity’s landing site was not based on 

traits favoring present-day habitability. However, much of 

the information this mission contributes about the modern environment will enhance our general understanding 

of Mars. For example, can organic compounds delivered 

by meteorites persist in the soil close to the surface? 

How does the modern atmosphere affect the ultraviolet 

and high-energy radiation that reaches the surface, posing a hazard to life and to preservation of organics? How 

might we better estimate levels in the past? The rover’s 

monitoring of radiation levels from cosmic rays and the 

sun also is designed to address astronaut safety on 

eventual human missions to Mars.

Science Payload

On April 14, 2004, NASA announced an opportunity 

for researchers to propose science investigations for 

the Mars Science Laboratory mission. The solicitation 

for proposals said, “The overall science objective of the 

MSL mission is to explore and quantitatively assess a 

potential habitat on Mars.” Eight months later, the agency 

announced selection of eight investigations proposed 

competitively. In addition, Spain and Russia would each 
Mars Science Laboratory Launch 11 Press Kit

provide an investigation through international agreements. The instruments for these 10 investigations make 

up the science payload on Curiosity.

The two instruments on the mast are a versatile, 

high-definition imaging system, and a laser-equipped, 

spectrum-reading camera that can hit a rock with a 

laser and observe the resulting spark for information 

about what chemical elements are in the rock. The 

tools on the turret at the end of Curiosity’s 7-foot-long 

(2.1-meter-long) robotic arm include a radiation-emitting 

instrument that reads X-ray clues to targets’ composition and a magnifying-lens camera. The arm can deliver 

soil and powdered-rock samples to an instrument that 

uses X-ray analysis to identify minerals in the sample 

and to an instrument that uses three laboratory methods 

for assessing carbon compounds and other chemicals 

important to life and indicative of past and present processes. For characterizing the modern environment, the 

rover also carries instruments to monitor the weather, 

measure natural radiation and seek evidence of water 

beneath the surface. To provide context for all the other 

instruments, a camera will record images of the landing 

area during descent.

The 10 science instruments on the Mars Science 

Laboratory have a combined mass of 165 pounds (75 

kilograms), compared with a five-instrument science 

payload totaling 11 pounds (5 kilograms) on each of the 

twin rovers, Spirit and Opportunity, that landed on Mars 

in 2004. The mass of just one of Curiosity’s 10 instruments, 88 pounds (40 kilograms) for Sample Analysis at 

Mars, is nearly four times the 23-pound (10.6-kilogram) 

total mass of the first Mars rover, 1997’s Sojourner on 

the Mars Pathfinder mission.

Assessing past and present habitability of environments 

at sites visited by Curiosity will require integrating the 

results of the various instruments, not any single instrument. Science operations and analysis will be coordinated through the Mars Science Laboratory Project 

Science Group, whose members are Project Scientist 

John Grotzinger, of the California Institute of Technology, 

Pasadena, Calif.; Program Scientist Michael Meyer of 

NASA Headquarters, Washington; and the principal 

investigator for each of the following investigations.

Mast Camera (Mastcam)

Two two-megapixel color cameras on Curiosity’s mast 

are the left and right eyes of the Mast Camera, or 

Mastcam investigation. These versatile cameras have 

complementary capabilities for showing the rover’s surroundings in exquisite detail and in motion.

The right-eye Mastcam looks through a telephoto lens, 

revealing details near or far with about three-fold better 

resolution than any previous landscape-viewing camera 

on the surface of Mars. The left-eye Mastcam provides 

broader context through a medium-angle lens. Each 

can acquire and store thousands of full-color images. 

Each is also capable of recording high-definition video. 

Combining information from the two eyes can yield 3-D 

views where the images overlap.

Mastcam imaging of the shapes and colors of landscapes, rocks and soils will provide clues about the history of environmental processes that have formed them 

and modified them over time. Images and videos of the 

sky will document contemporary processes, such as the 

movement of clouds and dust.

The telephoto Mastcam is called “Mastcam 100” for its 

100-millimeter focal-length lens. Its images cover an area 

about six degrees wide and five degrees tall, in 1,600 pixels by 1,200 pixels. This yields a scale of 2.9 inches (7.4 

centimeters) per pixel at a distance of about six-tenths of 

a mile (1 kilometer) and about 0.006 inch (150 microns) 

per pixel at a distance of 6.6 feet (2 meters). The camera 

provides enough resolution to distinguish a basketball 

from a football at a distance of seven football fields, or to 

read “ONE CENT” on a penny on the ground beside the 

rover. 

Its left-eye partner, called “Mastcam 34” for its 34-millimeter lens, catches a scene three times wider — about 

18 degrees wide and 15 degrees tall — on an identical 

detector. It can obtain images with 8.7 inches (22 centimeters) per pixel at a distance of about six-tenths of a 

mile (1 kilometer) and 0.018 inch (450 microns) per pixel 

at a distance of 6.6 feet (2 meters). 

The centers of Mastcam’s lenses sit about 6.5 feet (2.0 

meters) above ground level. The eyes are farther apart — 

about 10 inches (25 centimeters) — than the stereo eyes 

on earlier Mars surface robots. The cameras can focus 

on features at any distance from about 6 feet (just under 

2 meters) to infinity.

When Curiosity drives to a new location, the Mastcam 

34 can record a full-color, full-circle panorama showing 

everything from the nearby ground to the horizon by taking 150 images in about 25 minutes. Using the Mastcam 

100, the team will be able to see farther off to the sides of 
Mars Science Laboratory Launch 12 Press Kit

the rover’s path, compared with what has been possible 

with earlier Mars rovers. That will help with selection of 

the most interesting targets to approach for analyzing 

with Curiosity’s other instruments and will provide additional geological context for interpreting data about the 

chosen targets.

The Mastcams will provide still images and video to 

study motions of the rover — both for science, such 

as seeing how soils interact with wheels, and for engineering, such as aiding in use of the robotic arm. In 

other videos, the team may use cinematic techniques 

such as panning across a scene and using the rover’s 

movement for “dolly” shots. Video from the cameras is 

720p high definition at four to seven frames per second, 

depending on exposure time.

Malin Space Science Systems, San Diego, built the 

Mastcams and two of Curiosity’s other science instruments: the Mars Hand Lens Imager and the Mars 

Descent Imager. 

The four cameras from Malin Space Science Systems 

share several design features. They use a Bayer pattern filter, as found in many commercial digital cameras, 

for color imaging. The charge-coupled device (CCD) 

that detects each pixel of the image is covered with a 

grid of green, red and blue filters so that the camera 

gets the three color components over the entire scene 

in a single exposure. This is a change from color cameras on earlier Mars landers and rovers, which took a 

series of exposures through different filters to be combined into color composites by processing on Earth. 

The filter design used for Curiosity’s science cameras 

results in pictures in which the color closely mimics the 

way the average human eye sees the world. Each of 

the cameras uses a focusing mechanism from MDA 

Information Systems Space Division, formerly Alliance 

Spacesystems, Pasadena, Calif. Each uses a Kodak 

CCD with an array of 1,600 by 1,200 active pixels. Each 

has an eight-gigabyte flash memory. 

Besides the affixed red-green-blue filter grid, the 

Mastcams have wheels of other color filters that can be 

rotated into place between the lens and the CCD. These 

include science spectral filters for examining the ground 

or sky in narrow bands of visible-light or near-infrared 

wavelengths. These science filters can be used for 

follow-up observations to gain more information about 

rocks or other features of interest identified in red-greenblue images. One additional filter on each camera allows 

it to look directly at the sun to measure the amount of 

dust in the atmosphere, a key part of Mars’ weather.

Mastcam’s color-calibration target on the rover deck 

includes magnets to keep the highly magnetic Martian 

dust from accumulating on portions of color chips and 

white-gray-balance reference chips. Natural lighting on 

Mars tends to be redder than on Earth due to dust in 

Mars’ atmosphere. “True color” images can be produced that incorporate that lighting effect — comparable to the warm, orange lighting that is experienced at 

sunset on Earth. Alternatively, a white-balance calculation can be used to adjust for the tint of the lighting, as 

the human eye tends to do and digital cameras can do. 

The Mastcams are capable of producing both true-color 

and white-balanced images.

The Mastcam principal investigator is Michael Malin, a 

geologist who founded Malin Space Science Systems 

and has participated in NASA Mars exploration since the 

Mariner 9 mission in 1971–72.

Chemistry and Camera (ChemCam)

The investigation using a rock-zapping laser and a telescope mounted atop Curiosity’s mast is the Chemistry 

and Camera suite, or ChemCam. It also includes spectrometers and electronics down inside the rover. 

The laser can hit rock or soil targets up to about 23 

feet (7 meters) away with enough energy to excite a 

pinhead-size spot into a glowing, ionized gas, called 

plasma. The instrument observes that spark with the 

telescope and analyzes the spectrum of light to identify 

the chemical elements in the target. 

The telescope, with a diameter of 4.33 inches (110 

millimeters), doubles as the optics for the camera of 

ChemCam, which records monochrome images on 

a 1,024-pixel-by-1,024-pixel detector. The telescopic 

camera, called the remote micro-imager, will show context of the spots hit with the laser. It can also be used 

independently of the laser for observations of targets at 

any distance. 

Information from ChemCam will help researchers survey 

the rover’s surroundings and choose which targets to 

approach for study with the tools on the arm and the 

analytical laboratory instruments. ChemCam can also 

analyze many more targets than those instruments 

can. It can be used on multiple targets the same day, 
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while the analytical laboratory investigations — SAM 

and CheMin — take multiple days per target. It can also 

check the composition of targets inaccessible to the 

rover’s other ingredient-identifying instruments, such as 

rock faces beyond the reach of Curiosity’s robotic arm.

The spot hit by ChemCam’s infrared laser gets more 

than a million watts of power focused on it for five 

one-billionths of a second. Light from the resulting flash 

comes back to ChemCam through the telescope, then 

through about 20 feet (6 meters) of optical fiber down 

the mast to three spectrometers inside the rover. The 

spectrometers record intensity at 6,144 different wavelengths of ultraviolet, visible and infrared light (wavelengths from 240 to 850 nanometers). Different chemical 

elements in the target, in their ionized state, emit light 

at different wavelengths. Dozens of laser pulses on the 

same spot will be used to achieve the desired accuracy 

in identifying elements. Among the many elements that 

the instrument can identify in rocks and soils are sodium, 

magnesium, aluminum, silicon, calcium, potassium, 

titanium, manganese, iron, hydrogen, oxygen, beryllium, 

lithium, strontium, sulfur, nitrogen and phosphorus.

If a rock has a coating of dust or a weathered rind, 

hundreds of repeated pulses from the laser can remove 

those layers to provide a reading of the rock’s interior 

composition and a comparison between the interior and 

the coating. 

Researchers also plan to use ChemCam to study the 

soil at each place Curiosity stops. These observations 

will document local and regional variations in the soil’s 

composition and — from images taken through the telescope — in the size distribution of soil particles.

Another capability will be to check for water, either 

bound into mineral composition or as frost. By quickly 

identifying hydrogen and oxygen, ChemCam can provide unambiguous identification of water if any is on the 

surface in the area Curiosity explores.

ChemCam uses a technology called laser-induced 

breakdown spectroscopy. This method of determining 

the composition of an object has been used in other extreme environments, such as inside nuclear reactors and 

on the sea floor, and has had experimental applications 

in environmental monitoring and cancer detection, but 

ChemCam is its first use in interplanetary exploration.

Roger Wiens, a geochemist with the U.S. Department of 

Energy’s Los Alamos National Laboratory in Los Alamos, 

N.M., is the principal investigator for ChemCam. For 

developing, building and testing the instrument, Los 

Alamos partnered with researchers in France funded 

by the French national space agency, Centre National 

d’Études Spatiales. The deputy principal investigator 

is Sylvestre Maurice, a spectroscopy expert with the 

Institut de Recherche en Astrophysique et Planétologie 

at the Observatoire Midi-Pyrénées, Toulouse, France. 

France provided ChemCam’s laser and telescope. The 

laser was built by Thales, Paris, France. Los Alamos 

National Laboratory supplied the spectrometers and 

data processors. The optical design for the spectrometers came from Ocean Optics, Dunedin, Fla. The 

ChemCam team includes experts in mineralogy, geology, astrobiology and other fields, with some members 

also on other Curiosity instrument teams.

Alpha Particle X-Ray Spectrometer (APXS)

The Alpha Particle X-Ray Spectrometer (APXS) on 

Curiosity’s robotic arm, like its predecessors on the 

arms of all previous Mars rovers, will identify chemical 

elements in rocks and soils.

The APXS instruments on Sojourner, Spirit and 

Opportunity produced important findings from those 

missions, including salty compositions indicative of a 

wet past in bedrocks examined by Opportunity and 

the signature of an ancient hot spring or steam vent in 

soil examined by Spirit. The APXS on Curiosity delivers greater sensitivity, better scheduling versatility and a 

new mode for optimal positioning.

The Canadian Space Agency contributed this 

Canadian-made instrument for the Mars Science 

Laboratory. A pinch of radioactive material emits radiation that “queries” the target and an X-ray detector 

“reads” the answer.

The APXS sensor head, about the size of a cupcake, 

rides on the multi-tool turret at the end of Curiosity’s 

arm. The rover will place the spectrometer’s contactsensing surface directly onto most rock targets selected 

for APXS readings or just above some soil targets. 

The instrument determines the abundance of elements 

from sodium to strontium, including the major rockforming and soil-forming elements sodium, magnesium, 

aluminum, silicon, calcium, iron and sulfur. In 10-minute 

quick looks, it can detect even minor ingredients down 
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to concentrations of about one-half percent. In threehour readings, it can detect important trace elements 

down to concentrations of 100 or fewer parts per million. 

It has a high sensitivity to salt-forming elements such as 

sulfur, chlorine and bromine, which can indicate interaction with water in the past.

The APXS will characterize the geological context and 

inform choices about acquiring samples for analysis inside the mission’s analytical laboratory instruments: SAM 

and CheMin. Learning which elements, in what concentrations, are in the targets will help researchers identify 

processes that formed the rocks and soils in the area of 

Mars where Curiosity is working.

The spectrometer uses the radioactive element curium 

as a source to bombard the target with energetic alpha 

particles (helium nuclei) and X-rays. This causes each element in the target to emit its own characteristic X-rays, 

which are then registered by an X-ray detector chip 

inside the sensor head. The investigation’s main electronics package, which resides inside the rover, records 

all detected X-rays with their energy and assembles the 

detections into the X-ray spectrum of this sample.

On Spirit and Opportunity, the need for the X-ray detector chip to stay cold, and the length of time necessary 

for acquiring a measurement, have restricted most 

APXS measurements to Martian nighttime hours. One 

change in Curiosity’s APXS is the possibility to activate a 

solid-state electric cooler for the detector, for use of the 

APXS during Martian daytime. 

Curiosity’s APXS can make measurements in about 

one-third the time needed for equivalent readings by its 

predecessors. This improvement in sensitivity results 

mainly from shrinking the distance between the X-ray 

detector and the sample by about one-third, to 0.75 

inch (19 millimeters). 

Additional improvement in sensitivity, mainly for heavy 

elements such as iron, comes from increasing the 

amount X-rays emitted by the curium. Curiosity’s APXS

has about 700 micrograms (in mass) or 60 millicuries 

(in radioactivity), which is twice as much as Spirit’s or 

Opportunity’s. Curium is a synthetic element first identified in a laboratory in 1944. The specific isotope used in 

all Mars rovers’ APXS instruments is curium 244, which 

has a half-life of 18.1 years. This makes it ideal for longduration missions, where even after more than seven 

years of the Opportunity mission, the loss in activity is 

hardly noticeable. 

The additional X-ray intensity will benefit use of a technique called the scatter peak method, which was 

developed by physicist Iain Campbell, an APXS coinvestigator at the University of Guelph, Ontario, Canada. 

This method extracts the content of elements invisible 

to X-rays, such as oxygen. It was used to detect and 

quantify water bound in the minerals of salty subsurface 

soils examined by Spirit at Gusev Crater. 

When the spectrometer is in contact with the target, it 

examines a patch about 0.7 inch (1.7 centimeters) in 

diameter. It detects elements to a depth of about 0.0002 

inch (5 microns) for low-atomic-weight elements and to 

about 10 times that depth for heavier elements. The dust 

removal tool on Curiosity’s arm turret can be used to 

brush some rock surfaces clean before APXS examines 

them.

For some soil targets, to avoid pushing the instrument 

into the soil, the spectrometer will not be placed in direct 

contact with the target. In those cases, placement will 

use a standoff distance of about 0.4 inch (1 centimeter) 

or less. 

Another new feature for Curiosity’s APXS is an autonomous placement mode. With this software, as the arm 

moves the spectrometer step-by-step closer to the soil, 

the instrument checks X-rays from the target for several 

seconds at each step. When the count rate reaches a 

predetermined criterion of what would be adequate for a 

good compositional reading, the software knows, “OK. 

That’s close enough.” The arm’s approach movements 

cease and the longer-duration APXS reading begins. A 

more complex variation of this autonomous placement 

mode may use brief readings at several positions parallel 

to the ground surface, scanning a larger area for certain 

compositional criteria, such as ratio of iron to sulfur, and 

quickly selecting the most distinctive spots for longerduration readings.

Besides examining rocks and soils in place, the science 

team can use the APXS to check processed samples 

that the arm places on the rover’s observation tray and 

soil freshly exposed by action of the rover’s wheels. An 

onboard basaltic rock slab, surrounded by nickel plate, 

will be used periodically to check the performance and 

calibration of the instrument.

The principal investigator for Curiosity’s APXS is Ralf 

Gellert, a physicist at the University of Guelph in Ontario, 

Canada. He was part of the team that designed and 

built the Spirit and Opportunity APXS instruments at 
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the Max Planck Institute in Mainz, Germany, and provided the new scientific design for the Mars Science 

Laboratory APXS based on the experience gained 

through the long operation of those predecessors. MDA, 

in Brampton, Ontario, Canada, built the instrument as 

the prime contractor for the Canadian Space Agency. 

Mars Hand Lens Imager (MAHLI)

The Mars Hand Lens Imager, or MAHLI, is a focusable 

color camera on the tool-bearing turret at the end of 

Curiosity’s robotic arm. Researchers will use it for magnified, close-up views of rocks and soils, and also for 

wider scenes of the ground, the landscape or even the 

rover. Essentially, it is a hand-held camera with a macro 

lens and autofocus.

The investigation takes its name from the type of hand 

lens magnifying tool that every field geologist carries for 

seeing details in rocks. Color, crystal shapes, mineral 

cleavage planes and other visible details from such 

close-up observation provide clues to a rock’s composition. In sedimentary rocks, the sizes and shapes of the 

grains in the rock, and the scale of fine layering, provide 

information about how the grains were transported 

and deposited. Sharp-edge grains have not been worn 

down by tumbling long distances, for example. The size 

of grains can indicate whether the water or wind that 

carried them was moving quickly or not.

These clues garnered from MAHLI images can aid both 

in selection of which targets to analyze with other instruments and in directly reading the environmental history 

recorded in the rocks and soils the rover encounters. 

As a close-up magnifying camera, MAHLI resembles 

the Microscopic Imager instrument mounted at the 

end of the robotic arm on each of the twin Mars rovers 

Spirit and Opportunity. MAHLI has significantly greater 

capabilities than those predecessors, however: full color, 

lights and adjustable focus. Also, it sits on a longer arm, 

one that can hold MAHLI up higher than the cameras on 

the rover’s mast for seeing over an obstacle or capturing 

a rover self-portrait. 

When positioned at its closest range — about 0.8 inch 

(21 millimeters) from its target — the camera’s images 

have a resolution of slightly less than one one-thousandth of an inch (14 microns) per pixel. The field of 

view for that close-up is a rectangle about 0.9 inch (2.2 

centimeters) by 0.7 inch (1.7 centimeters). 

The camera can be held at a series of different distances from a target to show context as well as detail 

by adjusting the focus. At about 3 feet (1 meter) from 

a target, it still has a pixel resolution of about 0.02 inch 

(half a millimeter) in a view covering an area about 2 feet 

(70 centimeters) wide. By manipulation of arm position 

and focus, the camera can be used to examine hardware on the rover or record time-lapse views of activities such as opening a sample inlet cover. 

MAHLI has two sets of white light-emitting diodes to 

enable imaging at night or in deep shadow. Two other 

light-emitting diodes on the instrument glow at the ultraviolet wavelength of 365 nanometers. These will make it 

possible to check for materials that fluoresce under this 

illumination. 

Malin Space Science Systems, San Diego, developed, 

built and operates MAHLI. This camera shares some 

traits with three other cameras on Curiosity from the 

same company. It uses a red-green-blue filter grid like 

the one on commercial digital cameras for obtaining a 

full-color image with a single exposure. Its image detector is a charge-coupled device with an array of 1,600 by 

1,200 active pixels. It stores images in an eight-gigabyte 

flash memory, and it can perform an onboard focus 

merge of eight images to reduce from eight to two the 

number of images returned to Earth in downlink-limited 

situations.

Curiosity carries a vertically mounted calibration target 

for MAHLI, for checking color, white balance, resolution, 

focus and the ultraviolet illumination.

Ken Edgett of Malin Space Science Systems, a geologist who has helped run cameras on several Mars 

orbiters, is the principal investigator for MAHLI. A unified imaging-science team for the three Malin-supplied 

instruments combines experience in geologic field 

work, Mars exploration and space cameras.

Chemistry and Mineralogy (CheMin)

The Chemistry and Mineralogy experiment, or CheMin, 

is one of two investigations that will analyze powdered 

rock and soil samples delivered by Curiosity’s robotic 

arm. It will identify and quantify the minerals in the 

samples. Minerals provide a durable record of past 

environmental conditions, including information about 

possible ingredients and energy sources for life.
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CheMin uses X-ray diffraction, a first for a mission to 

Mars. This is a more definitive method for identifying 

minerals than was possible with any instrument on previous missions. The investigation supplements the diffraction measurements with X-ray fluorescence capability to 

determine further details of composition by identifying 

ratios of specific elements present. 

X-ray diffraction works by directing an X-ray beam at 

a sample and recording how X-rays are scattered by 

the sample at the atomic level. All minerals are crystalline, and in crystalline materials, atoms are arranged 

in an orderly, periodic structure, causing the X-rays to 

be scattered at predictable angles. From those angles, 

researchers can deduce the spacing between planes 

of atoms in the crystal. Each different mineral yields a 

known, characteristic series of spacings and intensities, 

its own fingerprint.

On Curiosity’s deck, near the front of the rover, one funnel with a removable cover leads through the deck top 

to the CheMin instrument inside the rover. The instrument is a cube about 10 inches (25 centimeters) on 

each side, weighing about 22 pounds (10 kilograms). 

The rover acquires rock samples with a percussive drill 

and soil samples with a scoop. A sample processing 

tool on the robotic arm puts the powdered rock or soil 

through a sieve designed to remove any particles larger 

than 0.006 inch (150 microns) before delivering the material into the CheMin inlet funnel. Vibration helps move 

the sample material — now a gritty powder — down the 

funnel. Each sample analysis will use about as much 

material as in a baby aspirin. 

The funnel delivers the sample into a disc-shaped cell, 

about the diameter of a shirt button and thickness of a 

business card. The walls of the sample cell are transparent plastic. Thirty-two of these cells are mounted around 

the perimeter of a sample wheel. Rotating the wheel can 

position any cell into the instrument’s X-ray beam. Five 

cells hold reference samples from Earth to help calibrate 

the instrument. The other 27 are reusable holders for 

Martian samples. 

Each pair of cells is mounted on a metal holder that 

resembles a tuning fork. A tiny piezoelectric buzzer excites the fork to keep the particles in the sample moving 

inside the cell during analysis of the sample. This puts 

the particles in a random mix of orientations to the X-ray 

beam, improving detection of how the mineral crystals in the sample scatter the X-rays. The piezoelectric 

vibration, at about 200 cycles per second (middle C on 

a piano is 261 cycles per second) also helps keep the 

powder flowing during filling and dumping of the cell. 

CheMin generates X-rays by aiming high-energy electrons at a target of cobalt. The X-rays emitted by the 

cobalt are then directed into a narrow beam. During 

analysis, the sample sits between the incoming beam 

on one side and the instrument’s detector on the other. 

The detector is a charge-coupled device like the ones in 

electronic cameras, but sensitive to X-ray wavelengths 

and cooled to minus 76 degrees Fahrenheit (minus 60 

degrees Celsius).

Each CheMin analysis of a sample requires up to 10 

hours of accumulating data while the X-rays are hitting the sample. The time may be split into two or more 

Martian nights of operation. 

The X-ray diffraction data show the angles at which the 

primary X-rays from the beam are deflected and the 

intensity at each angle. The detector also reads secondary X-rays emitted by the sample itself when it is excited 

by the primary X-rays. This is the X-ray fluorescence 

information. Different elements emit secondary X-rays at 

different frequencies. CheMin’s X-ray fluorescence capability can detect elements with an atomic number greater 

than 11 (sodium) in the periodic table.

Instruments that previous missions to Mars have used 

for studying Martian minerals have not been able to 

provide definitive identification of all types of minerals. 

CheMin will be able to do so for minerals present in 

samples above minimal detection limits of about 3 percent of the sample composition. The instrument will also 

indicate the approximate concentrations of different minerals in the sample. X-ray fluorescence can add information about the ratio of elements in types of minerals with 

variable elemental composition, such as the proportion 

of iron to magnesium in iron magnesium sulfate (olivine). 

It can also aid in identifying non-crystalline ingredients in 

a sample, such as volcanic glass. 

Each type of mineral forms under a certain set of environmental conditions: the chemistry present (including water), the temperature and the pressure. Thus, 

CheMin’s identification of minerals will provide information about the environment at the time and place where 

the minerals in the rocks and soils formed or were 

altered. Some minerals the instrument might detect, 

such as phosphates, carbonates, sulfates and silica, can 

help preserve biosignatures. Whether or not the mission 
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determines that the landing area has offered a favorable 

habitat for life, the inventory of minerals identified by 

CheMin will provide information about processes in the 

evolution of the planet’s environment.

David Blake, an expert in cosmochemistry and exobiology at NASA’s Ames Research Center, Moffett Field, 

Calif., is the principal investigator for CheMin. He began 

work in 1989 on a compact X-ray diffraction instrument 

for use in planetary missions. His work with colleagues 

has resulted in commercial portable instruments for use 

in geological field work on Earth, as well as the CheMin 

investigation. The spinoff instruments have found applications in screening for counterfeit pharmaceuticals in 

developing nations and in analyzing archaeological finds. 

NASA Ames Research Center won the 2010 

Commercial Invention of the Year Award from NASA 

for the tuning-fork powder vibration system used on 

CheMin. Blake and Philippe Sarazin of inXitu Inc., 

Campbell, Calif., a co-investigator on the CheMin team, 

developed the technology while Sarazin was working as 

a post-doctoral fellow at Ames. 

Sample Analysis at Mars (SAM)

The Sample Analysis at Mars investigation, or SAM, will 

use a suite of three analytical tools inside Curiosity to 

study chemistry relevant to life. One key job is checking for carbon-based compounds that on Earth are 

molecular building blocks of life. It will also examine the 

chemical state of other elements important for life, and 

it will assess ratios of different atomic weights of certain 

elements for clues about planetary change and ongoing 

processes.

SAM will examine gases from the Martian atmosphere 

and gases that ovens and solvents pull from powered 

rock and soil samples. Curiosity’s robotic arm will deliver 

the powdered samples to one of two inlet funnels on the 

rover deck. Atmospheric samples enter through filtered 

inlet ports on the side of the rover. 

SAM’s analytical tools fit into a microwave-oven-size box 

inside the front end of the rover. While it is the biggest of 

the 10 instruments on Curiosity, this tightly packed box 

holds instrumentation that would take up a good portion 

of a laboratory room on Earth. One focus during development was power efficiency. For example, the two 

ovens heat powdered samples to about 1,800 degrees 

Fahrenheit (1,000 degrees Celsius) drawing a maximum 

power of just 40 watts. More than a third of a mile (more 

than 600 meters) of wiring is inside SAM.

SAM can detect a fainter trace of organics and identify 

a wider variety of them than any instrument yet sent to 

Mars. It also can provide information about other ingredients of life and clues to past environments.

One of SAM’s tools, a mass spectrometer like those 

seen in many TV crime-solving laboratories, identifies 

gases by the molecular weight and electrical charge of 

their ionized states. It will check for several elements 

important for life as we know it, including nitrogen, phosphorous, sulfur, oxygen, hydrogen and carbon. 

Another tool, a tunable laser spectrometer, uses absorption of light at specific wavelengths to measure concentrations of methane, carbon dioxide and water vapor. 

It also identifies the proportions of different isotopes in 

those gases. Isotopes are variants of the same element 

with different atomic weights, such as carbon-13 and 

carbon-12, or oxygen-18 and oxygen-16. Ratios of 

isotopes can be signatures of planetary processes, 

such as how Mars might have lost much of its former 

atmosphere. 

The suite’s third analytical tool, a gas chromatograph, 

separates different gases from a mixture to aid identification. It detects organic compounds exiting a capillary 

column, and then it feeds the separated fractions to the 

mass spectrometer for a more definitive identification.

SAM also includes a sample manipulation system, and 

a chemical separation and processing laboratory to 

support the analytical tools. The sample manipulation 

system maneuvers 74 sample cups, each about onesixth of a teaspoon (0.78 cubic centimeter) in volume. 

The chemical separation and processing laboratory 

includes pumps, tubing, carrier-gas reservoirs, pressure 

monitors, ovens, temperature monitors and other components. Fifty-two specially designed microvalves direct 

the flow of gas through the system. Two soft-drink-cansize vacuum pumps rotate 100,000 times per minute 

to allow all three instruments to operate at their optimal 

pressures.

SAM’s analysis of material from Martian rocks or soils 

begins after powder collected and processed by tools 

on the arm is dropped into one of SAM’s two solid-sample inlets while the inlet’s protective cover is open. The 

inlet tubes are highly polished funnels that vibrate to get 

the powder to fall into a reusable sample cup. 
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Fifty-nine of the instrument’s 74 cups are quartz that 

can be heated to very high temperatures. The sample 

manipulation system pushes the quartz cup holding 

the powder into an oven that heats it to about 1,800 

degrees Fahrenheit (about 1,000 degrees Celsius. That 

process releases gas from the sample at various temperatures, depending on the chemistry of the sample. 

The mass spectrometer measures the release continuously. Some of the gas goes to the tunable laser spectrometer for measurement of isotopes. Some goes to 

a trap that concentrates any organics, then to the gas 

chromatograph and mass spectrometer. After use, the 

quartz cup can be baked to prepare it for re-use with 

another sample.

Six of the cups hold calibration solids. SAM also carries 

samples of gases for calibration.

Nine of the cups are for using a solvent method called 

derivatization, rather than high temperature, to pull gases 

from samples of Martian rocks and soils. If the mission finds a site rich in organics, this method could be 

used to identify larger and more reactive organic molecules than is possible with the high-heat method. Each 

derivatization cup contains a mixture of a solvent and a 

chemical that, after it reacts with a compound of interest, 

turns it into a more volatile compound that can be separated in the gas chromatograph. These chemicals are 

entirely sealed in with a foil cover. For analysis of sample 

powder from a Martian rock or soil by this method, the 

sample manipulation system punctures the foil and adds 

the powder to the liquid in the cup, and the oven heats 

the sample to a modest temperature to let the reactions 

proceed rapidly.

Curiosity’s “follow the carbon” investigation of organic 

compounds begins as a check for whether any are present. Although organic molecules are not, in themselves, 

evidence of life, life as we know it cannot exist without 

them. Their presence would be important evidence 

both about habitability and about the site’s capability for 

preserving evidence of life. Meteorites bearing organic 

compounds have pelted Mars, as well as Earth, for 

billions of years. Uncertainty remains, however, about 

whether any organics close enough to the surface for 

Curiosity to reach them can persist in the harsh conditions there without the carbon in them transforming into 

a more polymerized state. 

NASA’s investigation of organics on Mars began with 

the twin Viking landers in 1976. The original reports from 

Viking came up negative for organics. SAM renews the 

search with three advantages. 

The first is Curiosity’s access. Mars is diverse, not 

uniform. Copious information gained from Mars orbiters 

in recent years has enabled the choice of a landing site 

with favorable attributes, such as exposures of clay and 

sulfate minerals good at entrapping organic chemicals. 

Mobility helps too, especially with the aid of high-resolution geologic mapping generated from orbital observations. The stationary Viking landers could examine only 

what their arms could reach. Curiosity can use mapped 

geologic context as a guide in its mobile search for 

organics and other clues about habitable environments. 

Additionally, SAM will be able to analyze samples from 

more protected interiors of rocks drilled into by Curiosity, 

rather than being restricted to soil samples, as Viking 

was.

Second, SAM has improved sensitivity, with a capability to detect less than one part-per-billion of an organic 

compound over a wider mass range of molecules and 

after heating samples to a higher temperature.

Third, the derivatization method for assessing organics in some SAM samples can reveal a wider range of 

organic compounds than was possible with the Viking 

experiment. In doing so, it can also check a recent hypothesis that a reactive chemical recently discovered in 

Martian soil — perchlorate — may have masked organics in soil samples baked during Viking tests.

If SAM does not detect any organics, that would be 

useful information about the unfavorable conditions for 

life near the Martian surface. Future missions might look 

deeper.

If SAM does detect organics, one challenge will be 

to confirm that these molecules are truly Martian, not 

stowaways from Earth carried to Mars on Curiosity. The 

rover carries five encapsulated bricks of organic check 

material to enable control experiments. The check 

material is a silicon-dioxide ceramic laced with small 

amounts of synthetic fluorinated organic chemicals not 

found in nature on Earth and not expected on Mars. 

The basic control experiment will collect a powdered 

sample from an organic check brick with the same drilling, processing and delivery system used for collecting 

samples from Martian rocks, and then will analyze the 

sample with SAM. If SAM finds any organics other than 

the fluorine-containing markers, they will be stowaway 
Mars Science Laboratory Launch 19 Press Kit

suspects. If only the markers are detected, that would 

verify that organic-detection is working and that the 

sample-acquisition and handling pathway has passed a 

test of being clean of organic stowaways. That control experiment can assess characteristics of organic 

contamination at five different times during the mission, 

using the five bricks of organic check material.

If organic chemicals are present in Martian samples, 

SAM’s inventory of the types and mixtures may provide 

clues to their origin. For example, organics delivered 

by meteorites without involvement of biology come 

with more random chemical structures than the patterns seen in mixtures of organic chemicals produced 

by organisms. Patterns, such as a predominance of 

molecules with an even number of carbon atoms, could 

be suggestive of biological origin. The derivatization 

process also allows searching for specific classes of 

organics with known importance to life on Earth. For 

example, it can identify amino acids, the chain links of 

proteins. While these clues may not add up to a definitive case either for or against biological origin, they could 

provide important direction for future missions.

Methane is one of the simplest organic molecules. 

Observations from Mars orbit and from Earth in recent 

years have suggested transient methane in Mars’ atmosphere, which would mean methane is being actively 

added and then removed from the atmosphere of Mars. 

With SAM’s laser spectrometer, researchers will check 

to confirm whether methane is present, monitor any 

changes in its concentration, and look for clues about 

whether Mars methane is produced by biological activity 

or by processes that do not require life.

The principal investigator for SAM is Paul Mahaffy, 

a chemist at NASA’s Goddard Space Flight Center, 

Greenbelt, Md. He is a veteran of using spacecraft 

instruments to study planetary atmospheres. Mahaffy 

has coordinated work of hundreds of people in several 

states and Europe to develop, build and test SAM after 

NASA selected his team’s proposal for it in 2004. 

NASA Goddard Space Flight Center built and tested 

SAM. France’s space agency, Centre National d’Études 

Spatiales, provided support to French researchers who 

developed SAM’s gas chromatograph. NASA’s Jet 

Propulsion Laboratory, Pasadena, Calif., provided the 

laser spectrometer. Honeybee Robotics, New York, 

designed SAM’s sample manipulation system.

Rover Environmental Monitoring Station (REMS)

The Rover Environmental Monitoring Station, or REMS, 

will record information about daily and seasonal changes in Martian weather.

This investigation will assess wind speed, wind direction, 

air pressure, relative humidity, air temperature, ground 

temperature, and ultraviolet radiation. Operational plans 

call for taking measurements for at least five minutes 

every hour of the full-Martian-year (98-week) mission.

Spain provided this instrument for the Mars Science 

Laboratory.

Information about wind, temperatures and humidity 

comes from electronic sensors on two finger-like booms 

extending horizontally from partway up the main vertical 

mast holding the ChemCam laser and the Mastcam. 

Each of the booms holds a sensor for recording air temperature and three sensors for detecting air movement 

in three dimensions. Placement of the booms at an 

angle of 120 degrees from each other enables calculating the velocity even when the main mast is blocking the 

wind from one direction. The boom pointing toward the 

front of the rover, Boom 2, also holds the humidity sensor inside a downward-tilted protective cylinder. Boom 

1, pointing to the side and slightly toward the rear, holds 

an infrared sensor for measuring ground temperature.

The pressure sensor sits inside the rover body, connected to the external atmosphere by a tube to a small, 

dust-shielded opening on the deck. Electronics controlling REMS are also inside the rover body.

The ultraviolet sensor is on the rover deck. It measures 

six different wavelength bands in the ultraviolet portion of the electromagnetic spectrum, including wavelengths also monitored from above by NASA’s Mars 

Reconnaissance Orbiter. No previous mission to the 

surface of Mars has measured the full ultraviolet spectrum of radiation. 

The REMS investigation will strengthen understanding 

about the global atmosphere of Mars and contribute to 

the mission’s evaluation of habitability. 

The data will provide a way to verify and improve atmosphere modeling based mainly on observations from 

Mars orbiters. For example, significant fractions of the 

Martian atmosphere freeze onto the ground as a south 
Mars Science Laboratory Launch 20 Press Kit

polar carbon-dioxide ice cap during southern winter and 

as a north polar carbon-dioxide ice cap during northern 

winter, returning to the atmosphere in each hemisphere’s 

spring. At Curiosity’s landing site, far from either pole, 

REMS will check whether seasonal patterns of changing 

air pressure fit the existing models for effects of the coming and going of polar carbon-dioxide ice.

Monitoring ground temperature with the other weather 

data could aid in assessment of whether conditions have 

been favorable for microbial life. Even in the extremely 

low-humidity conditions anticipated in the landing area, 

the combination of ground temperature and humidity 

information could provide insight about the interaction of 

water vapor between the soil and the atmosphere. If the 

environment supports, or ever supported, any underground microbes, that interaction could be crucial.

Ultraviolet radiation can also affect habitability. The ultraviolet measurements by REMS will allow scientists to 

better predict the amount of ultraviolet light that reaches 

Mars’ surface globally in the present and past. Ultraviolet 

light is destructive to organic material and the reason 

that sunscreen is worn on Earth.

The principal investigator for REMS is Javier GómezElvira, an aeronautical engineer with the Center for 

Astrobiology (Centro de Astrobiología), Madrid, Spain. 

The center is affiliated with the Spanish National 

Research Council (Consejo Superior de Investigaciones 

Científicas) and the National Institute for Aerospace 

Technology (Instituto Nacional de Técnica Aerospacial). 

Spain’s Ministry of Science and Innovation (Ministerio de 

Ciencia e Innovación) and Spain’s Center for Industrial 

Technology Development (Centro para el Desarrollo 

Tecnológico Industrial) supplied REMS. The Finnish 

Meterological Insitute developed the pressure sensor.

To develop the instrument and prepare for analyzing 

the data it will provide, Spain has assembled a team of 

about 40 researchers — engineers and scientists. 

The team plans to post daily weather reports from 

Curiosity. Air temperature around the rover mast will likely 

drop to about minus 130 degrees Fahrenheit (about 

minus 90 degrees Celsius) on some winter nights and 

climb to about minus 22 Fahrenheit (about minus 30 

Celsius) during winter days. In warmer seasons, afternoon air temperature could reach a balmy 32 Fahrenheit 

(0 degrees Celsius).

Radiation Assessment Detector (RAD)

The Radiation Assessment Detector, or RAD, investigation on Curiosity will monitor high-energy atomic and 

subatomic particles reaching Mars from the sun, from 

distant supernovas and other sources. These particles 

constitute naturally occurring radiation that could be 

harmful to any microbes near the surface of Mars or to 

astronauts on a future Mars mission. 

RAD’s measurements will help fulfill the Mars Science 

Laboratory mission’s key goals of assessing whether 

Curiosity’s landing region has had conditions favorable 

for life and for preserving evidence about life. This investigation will also do an additional job. Unlike the rest 

of the mission, RAD has a special task and funding from 

the part of NASA that is planning human exploration 

beyond Earth orbit. It will aid design of human missions 

by reducing uncertainty about how much shielding 

from radiation future astronauts will need. RAD will take 

measurements during the trip from Earth to Mars as well 

as during Curiosity’s roving on Mars because the radiation levels in interplanetary space are also important in 

design of human missions.

The 3.8-pound (1.7-kilogram) RAD instrument has a 

wide-angle telescope looking upward from the hardware’s position inside the left-front area of the rover. 

The telescope has detectors for charged particles with 

masses up to that of an iron ion. RAD can also detect neutrons and gamma rays coming from the Mars 

atmosphere above or the Mars surface material below 

the rover.

Galactic cosmic rays make up one type of radiation 

that RAD will monitor. These are a variable shower of 

charged particles coming from supernova explosions 

and other events extremely far from our solar system. 

The sun is the other main source of energetic particles 

that this investigation will detect and characterize. The 

sun spews electrons, protons and heavier ions in “solar 

particle events” fed by solar flares and ejections of matter from the sun’s corona. Astronauts might need to 

move into havens with extra shielding on an interplanetary spacecraft or on Mars during solar particle events.

Earth’s magnetic field and atmosphere provide effective 

shielding against the possible deadly effects of galactic 

cosmic rays and solar particle events. Mars lacks a 

global magnetic field and has only about one percent 

as much atmosphere as Earth does. Just to find high-
Mars Science Laboratory Launch 21 Press Kit

enough radiation levels on Earth for checking and calibrating RAD, the instrument team needed to put it inside 

major particle-accelerator research facilities in the United 

States, Europe, Japan and South Africa.

The radiation environment at the surface of Mars has 

never been fully characterized. NASA’s Mars Odyssey 

orbiter, which reached Mars in 2001, assessed radiation 

levels above the Martian atmosphere with an investigation named the Mars Radiation Environment Experiment. 

Current estimates of the radiation environment at the 

surface rely on modeling of how the thin atmosphere 

affects the energetic particles, but uncertainty in the 

modeling remains large. A single energetic particle hitting 

the top of the atmosphere can break up into a cascade 

of lower-energy particles that might be more damaging 

than a single high-energy particle.

In addition to its precursor role for human exploration, 

RAD will contribute to the mission’s assessment of 

Mars’ habitability for microbes and search for organics. 

Radiation levels probably make the surface of modern 

Mars inhospitable for microbial life and would contribute to the breakdown of any near-surface organic 

compounds. The measurements from RAD will feed 

calculations of how deeply a possible future robot on a 

life-detection mission might need to dig or drill to reach a 

microbial safe zone. For assessing whether the surface 

radiation environment could have been hospitable for 

microbes in Mars’ distant past, researchers will combine 

RAD’s measurements with estimates of how the activity 

of the sun and the atmosphere of Mars have changed in 

the past few billion years.

Radiation levels in interplanetary space vary on many 

time scales, from much longer than a year to shorter 

than an hour. Assessing the modern radiation environment on the surface will not come from a one-time set of 

measurements. Operational planning for Curiosity anticipates that RAD will record measurements for 15 minutes 

of every hour throughout the prime mission, on steady 

watch so that it can catch any rare but vitally important 

solar particle events.

The first science data from the mission will come from 

RAD’s measurements during the trip from Earth to Mars. 

These en-route measurements will, first, enable correlations with instruments on other spacecraft that monitor 

solar particle events and galactic cosmic rays in Earth’s 

neighborhood and then will yield data about the radiation 

environment farther from Earth. 

RAD’s principal investigator is physicist Don Hassler 

of the Southwest Research Institute’s Boulder, Colo., 

branch. His international team of co-investigators 

includes experts in instrument design, astronaut safety, 

atmospheric science, geology and other fields.

Southwest Research Institute in Boulder and in San 

Antonio, Texas, together with Christian Albrechts 

University in Kiel, Germany, built RAD with funding from 

the NASA Exploration Systems Mission Directorate 

and Germany’s national aerospace research center, 

Deutsches Zentrum für Luft- und Raumfahrt.

Measurements of ultraviolet radiation by Curiosity’s 

Rover Environmental Monitoring Station will supplement 

RAD’s measurements of other types of radiation.

Dynamic Albedo of Neutrons (DAN)

The Dynamic Albedo of Neutrons investigation, or DAN, 

can detect water bound into shallow underground minerals along Curiosity’s path. 

The DAN instrument shoots neutrons into the ground 

and measures how they are scattered, giving it a high 

sensitivity for finding any hydrogen to a depth of about 

20 inches (50 centimeters) directly beneath the rover. 

The Russian Federal Space Agency contributed DAN 

to NASA as part of a broad collaboration between the 

United States and Russia in the exploration of space.

The instrument can be used in reconnaissance to identify places for examination with Curiosity’s other tools. 

Also, rock formations that Curiosity’s cameras view 

at the surface may be traced underground by DAN, 

enhancing the ability of scientists to understand the 

geology.

DAN will bring to the surface of Mars an enhancement 

of nuclear technology that has already detected Martian 

water from orbit. “Albedo” in the investigation’s name 

means reflectance — in this case, how high-energy 

neutrons injected into the ground bounce off of atomic 

nuclei in the ground. Neutrons that collide with hydrogen atoms bounce off with a characteristic decrease in 

energy, like one billiard ball hitting another. By measuring 

the energies of the reflected neutrons, DAN can detect 

the fraction that was slowed in these collisions, and 

therefore the amount of hydrogen. 
Mars Science Laboratory Launch 22 Press Kit

Oil prospectors use this technology in instruments 

lowered down exploration holes to detect the hydrogen 

in petroleum. Space explorers have adapted it for missions to the moon and Mars, where most hydrogen is in 

water ice or in water-derived hydroxyl ions. 

DAN Principal Investigator Igor Mitrofanov of Space 

Research Institute, Moscow, is also the principal investigator for a Russian instrument on NASA’s Mars 

Odyssey orbiter, the high energy neutron detector, 

which measures high energy of neutrons coming 

from Mars. In 2002, it and companion instruments on 

Odyssey detected hydrogen interpreted as abundant 

underground water ice close to the surface at high 

latitudes. 

The neutron detectors on Odyssey rely on galactic cosmic rays hitting Mars as a source of neutrons. DAN can 

work in a passive mode relying on cosmic rays, but it 

also has its own pulsing neutron generator for an active 

mode of shooting high-energy neutrons into the ground. 

In active mode, it is sensitive enough to detect water 

content as low as one-tenth of 1 percent in the ground 

beneath the rover. 

The neutron generator is mounted on Curiosity’s right 

hip, a pair of neutron detectors on the left hip. Pulses 

last about one microsecond and repeat as frequently as 

10 times per second. The detectors measure the flow of 

moderated neutrons with different energy levels returning from the ground, and their delay times. Neutrons 

that arrive later may indicate water buried beneath a 

drier soil layer. The generator will be able to emit a total 

of about 10 million pulses during the mission, with about 

10 million neutrons at each pulse. 

The most likely form of hydrogen in the ground of the 

landing area is hydrated minerals. These are minerals 

with water molecules or hydroxyl ions bound into the 

crystalline structure of the mineral. They can tenaciously 

retain water from a wetter past when all free water has 

gone. DAN may also detect water that comes and 

goes with the Martian seasons, such as soil moisture 

that varies with the atmospheric humidity. Together 

with Curiosity’s cameras and weather station, DAN will 

observe how the sparse water cycle on Mars works in 

the present. DAN also could detect any water ice in the 

shallow subsurface, a low probability at Curiosity’s Gale 

Crater landing site.

Operational planning anticipates using DAN during short 

pauses in drives and while the rover is parked. It will 

check for any changes or trends in subsurface hydrogen content from place to place along the traverse. 

Russia’s Space Research Institute developed the DAN 

instrument in close cooperation with the N.L. Dukhov 

All-Russia Research Institute of Automatics, Moscow, 

and the Joint Institute of Nuclear Research, Dubna.

Mars Descent Imager (MARDI)

During the final few minutes of Curiosity’s flight to the 

surface of Mars, the Mars Descent Imager, or MARDI, 

will record a full-color video of the ground below. This 

will provide the Mars Science Laboratory team with information about the landing site and its surroundings, to 

aid interpretation of the rover’s ground-level views and 

planning of initial drives. Hundreds of the images taken 

by the camera will show features smaller than what can 

be discerned in images taken from orbit. 

The video will also give fans worldwide an unprecedented sense of riding a spacecraft to a landing on Mars.

MARDI will record the video on its own 8 gigabyte flash 

memory at about four frames per second and close to 

1,600 by 1,200 pixels per frame. Thumbnails and a few 

samples of full-resolution frames will be transmitted to 

Earth in the first days after landing. The nested set of 

images from higher altitude to ground level will enable 

pinpointing of Curiosity’s location. The pace of sending 

the rest of the frames for full-resolution video will depend on sharing priority with data from the rover’s other 

investigations.

The full video — available first from the thumbnails in 

YouTube-like resolution and later in full detail — will 

begin with a glimpse of the heat shield falling away from 

beneath the rover. The first views of the ground will 

cover an area several kilometers (a few miles) across. 

Successive frames taken as the vehicle descends will 

close in and cover successively smaller areas. The video 

will likely nod up and down to fairly large angles owing 

to parachute-induced oscillations. Its roll clockwise and 

counterclockwise will be smaller, as thrusters on the descent stage control that motion. When the parachute is 

jettisoned, the video will show large angular motions as 

the descent vehicle maneuvers to avoid re-contacting 

the back shell and parachute. Rocket engine vibration 

may also be seen. A few seconds before landing, the 

rover will be lowered on tethers beneath the descent 

stage, and the video will show the relatively slow approach to the surface. The final frames, after landing, 
Mars Science Laboratory Launch 23 Press Kit

will cover a bath-towel-size patch of ground under the 

front-left corner of the rover.

Besides the main objective of providing geologic context 

for the observations and operations of the rover during 

the early part of mission on Mars, MARDI will provide 

insight about Mars’ atmosphere. Combining information from the descent images with information from the 

spacecraft’s motion sensors will allow for calculating 

wind speeds affecting the spacecraft on its way down, 

an important atmospheric science measurement. The 

descent data will later aid in designing and testing future 

landing systems for Mars that could add more control for 

hazard avoidance.

Throughout Curiosity’s mission on Mars, MARDI will offer 

the capability to obtain images of ground beneath the 

rover at resolutions down to 0.06 inch (1.5 millimeters) 

per pixel, for precise tracking of its movements or for 

geologic mapping. The science team will decide whether 

or not to use that capability. Each day of operations on 

Mars will require choices about how to budget power, 

data and time.

Malin Space Science Systems, San Diego, provided 

MARDI, as well as three other cameras on Curiosity: 

the Mast Camera pair and the Mars Hand Lens Imager. 

Michael Malin is the principal investigator for MARDI, 

which shares a unified imaging-science team with the 

other two instruments from his company.

MARDI consists of two parts: the wide-angle camera 

mounted toward the front of the port side of Curiosity 

and a digital electronics assembly inside the warm 

electronics box of the rover’s chassis. The instrument’s 

electronics, including the 1,600-pixel-by-1,200-pixel 

charge-coupled device (CCD) in the camera, are the 

same design as used in the Mast Camera and Mars 

Hand Lens Imager. 

The rectangular field of the CCD sits within a 90-degree 

circular field of view of the camera lens, yielding a recorded field of view of 70 degrees by 55 degrees. From 

an altitude of 1.2 miles (2 kilometers) during descent that 

will provide a resolution of about 5 feet (1.5 meters) per 

pixel, though swinging and shaking of the spacecraft will 

likely blur some frames despite a fast (1.3 millisecond) 

exposure time. 

Color information comes from a Bayer pattern filter array, 

as used in many commercial digital cameras. The camera’s CCD is covered with a grid of green, red and blue 

filters so that each exposure samples all of those colors 

throughout the field of view. A piece of white material 

on the inside surface of the heat shield will serve as a 

white-balance target as the heat shield falls away at the 

beginning of the recorded descent video.

Malin Space Science Systems also provided descent 

imagers for NASA’s Mars Polar Lander, launched in 

1999, and Phoenix Mars Lander, launched in 2007. 

However, the former craft was lost during its landing and 

the latter did not use its descent imager due to concern 

about the spacecraft’s data-handling capabilities during 

crucial moments just before landing.

Engineering Instruments

Some of the tools that primarily serve engineering 

purposes on Mars Science Laboratory will also generate information useful to scientific understanding about 

Mars. Most of these, including the engineering cameras 

and the drill, are described in the spacecraft section 

of this document. One set of instruments carried on 

the heat shield of the spacecraft’s entry vehicle serves 

specifically to gather data about the Martian atmosphere 

and performance of the heat shield for use in designing future systems for descending through planetary 

atmospheres. 

MSL Entry, Descent and Landing Instrument 

(MEDLI) Suite

A set of sensors attached to the heat shield of the Mars 

Science Laboratory (MSL) is collectively named the MSL 

Entry, Descent and Landing Instrument (MEDLI) Suite. 

MEDLI will take measurements eight times per second 

during the period from about 10 minutes before the vehicle enters the top of the Martian atmosphere until after 

the parachute has opened, about four minutes after 

entry. The measurements will be analyzed for information about atmospheric conditions and performance of 

the entry vehicle. 

Due to the mass of the entry vehicle (5,359 pounds, or 

2,431 kilograms, after jettison of the spacecraft’s cruise 

stage), the diameter of its heat shield (14.8 feet, or 4.5 

meters) and the speed at which the vehicle will enter the 

atmosphere (13,645 miles per hour, or 6.1 kilometers 

per second), the heating and stress on the heat shield 

will be the highest ever for an entry vehicle at Mars. 

Experience gained with this mission will aid planning for 
Mars Science Laboratory Launch 24 Press Kit

future missions that could be even heavier and larger, 

such as would be necessary for a human mission to 

Mars. 

Models of the Martian atmosphere, heating environments, vehicle aerodynamics, and heat-shield performance, among other factors, were employed in 

designing the Mars Science Laboratory entry vehicle. 

Uncertainties in these parameters must also be modeled. To account for those uncertainties, the design 

incorporates large margins for success. The margin 

comes at a cost of additional mass. The goal of MEDLI

is to better quantify these atmospheric entry characteristics and possibly reduce unnecessary mass on future 

Mars missions, by collecting data on the performance 

of the Mars Science Laboratory entry vehicle during its 

atmospheric entry and descent. 

MEDLI consists of seven pressure sensors (Mars entry 

atmospheric data system sensor, or MEADS), seven 

plugs with multiple temperature sensors (Mars integrated sensor plug, or MISP) and a support electronics box. 

Data from the entry vehicle’s inertial measurement unit, 

which senses changes in velocity and direction, will augment the MEDLI data. Each of the temperature-sensing 

plugs has thermocouples to measure temperatures at 

four different depths in the heat shield’s thermal protection tiles, plus a sensor to measure the rate at which 

heat shield material is removed due to atmospheric 

entry heating. 

Analysis of data from the pressure sensors and inertial measurement unit will provide an altitude profile of 

atmospheric density and winds, plus information about 

pressure distribution on the heat shield surface, orientation of the entry vehicle and velocity. Data from the temperature sensors will be used to evaluate peak heating, 

distribution of heating over the heat shield, turbulence 

in the flow of gas along the entry vehicle’s surface, and 

in-depth performance of the heat shield material.

NASA’s Exploration Systems Mission Directorate (which 

has responsibility for planning human missions beyond Earth orbit) and Aeronautics Research Mission 

Directorate (which invests in fundamental research 

of atmospheric flight) have funded MEDLI. F. McNeil 

Cheatwood of NASA’s Langley Research Center, 

Hampton, Va., is the principal investigator for MEDLI. 

Deputy principal investigator is Michael Wright of 

NASA’s Ames Research Center, Moffett Field, Calif.
Mars Science Laboratory Launch 25 Press Kit

Mission Overview

NASA’s Mars Science Laboratory mission will put a 

mobile laboratory onto the surface inside Gale Crater 

on Mars and use it to investigate the area’s past and 

present environments. The landing will use active guidance for improved landing accuracy and a skycrane 

for touchdown. The mobile laboratory is the Curiosity 

rover, equipped with 10 science investigations and a 

robotic arm that can drill into rocks, scoop up soil and 

deliver samples to internal analytical instruments. The 

mission will assess whether the area has offered conditions favorable for life and favorable for preserving a rock 

record of evidence about whether life has existed there. 

Curiosity has the capability to drive for 12.4 miles (20 

kilometers) or more during a mission lasting one Martian 

year (98 weeks). 

Launch Vehicle

A two-stage Atlas V 541 launch vehicle will lift the Mars 

Science Laboratory spacecraft from Launch Complex 

41 at Cape Canaveral Air Force Station, Fla. The vehicle 

is provided by United Launch Alliance, a joint venture of 

Boeing Co. and Lockheed Martin Corp. The thee numbers in the 541 designation signify a payload fairing, or 

nose cone, that is approximately 5 meters (16.4 feet) in 

diameter; four solid-rocket boosters fastened alongside 

the central common core booster; and a one-engine 

Centaur upper stage.

Centerpiece of the first stage is the common core 

booster, 106.5 feet (32.5 meters) in length and 12.5 

feet (3.8 meters) in diameter. It has a throttleable, 

RD-180 engine from a joint venture of Pratt & Whitney 

Rocketdyne, West Palm Beach, Fla., and NPO 

Energomash, Moscow. Thermally stable kerosene fuel 

(type RP-1) and liquid oxygen will be loaded shortly 

before launch into cylindrical fuel tanks that make up 

about half of the total height of the vehicle. The common 

core booster can provide thrust of up to about 850,000 

pounds (3.8 million newtons) at full throttle.

Four solid rocket boosters strapped onto the common 

core booster add to the thrust that will be produced by 

the first stage. Each of these boosters is 64 feet (19.5 

meters) long and 61 inches (155 centimeters) in diamAtlas V 541 launch vehicle, expanded view
Mars Science Laboratory Launch 26 Press Kit

eter, and delivers about 306,000 pounds (1.36 million 

newtons) of thrust.

Two interstage adaptors connect the first stage of 

the Atlas with its Centaur upper stage. The Centaur 

has a restartable RL-10 engine from Pratt & Whitney 

Rocketdyne. This engine uses liquid hydrogen and liquid 

oxygen and can provide up to about 22,300 pounds 

(99,200 newtons) of thrust. The Centaur can control its 

orientation precisely, which is important for managing the 

direction of thrust while its engine is firing. It carries its 

own flight control computer and can release its payload 

with the desired attitude and spin rate.

The spacecraft will ride into the sky inside a protective 

payload fairing atop the Centaur stage. With the payload 

fairing on top, the vehicle ready for launch will stand approximately 191 feet (58 meters) tall.

The first Atlas V was launched in August 2002. An Atlas 

V 401 sent NASA’s Mars Reconnaissance Orbiter on its 

way to Mars on Aug. 12, 2005, from the same launch 

complex where the Mars Science Laboratory will be 

launched.

Launch Timing Factors

As Earth and Mars race around the sun, with Earth on 

the inside track, Earth laps Mars about once every 26 

months. Launch opportunities to Mars occur at the same 

frequency, when the planets are configured so that a 

spacecraft launched from Earth will move outward and 

intersect with Mars in its orbit several months later. This 

planetary clockwork, plus the launch vehicle’s power, the 

spacecraft’s mass, and the desired geometry and timing 

for the landing on Mars were all factors in determining the 

range of possible launch dates.

An additional factor in determining the launch period 

for the Mars Science Laboratory was the launch period 

from Aug. 5 to Aug. 26, 2011, for NASA’s Juno mission 

to Jupiter. The Juno launch on Aug. 5 used an Atlas 

V 551 vehicle from the same launch complex as the 

Mars Science Laboratory, Launch Complex 41 at Cape 

Canaveral Air Force Station, Fla. Consideration was 

given to the minimum time required to process the Mars 

Science Laboratory launch vehicle for its launch following Juno’s departure. This was an important factor in the 

choice of the type of trajectory to Mars and the timing of 

the launch period for the Mars Science Laboratory.

One priority for choice of a launch period within the 

range of possible dates has been to have the landing 

occur when NASA orbiters at Mars are passing over 

the landing site so they can receive radio transmissions 

from the Mars Science Laboratory spacecraft during 

its descent through the atmosphere and landing. If the 

landing is not successful, this strategy will provide much 

more information than would be possible with the alternative of relying on transmissions from the Mars Science 

Laboratory directly to Earth. Landing on Mars is always 

difficult, with success uncertain. After an unsuccessful 

attempted Mars landing by Mars Polar Lander in 1999 

without definitive information on the cause of the mishap, NASA set a high priority on communication during 

subsequent Mars landings. 

The selected launch period for the Mars Science 

Laboratory begins Nov. 25, 2011, and ends Dec. 18, 

2011. The durations of the daily launch windows during 

this 24-day launch period vary from day to day. On the 

first day in the launch period, the launch window is 103 

minutes long. The windows will shorten to 44 minutes 

by the end of the period. Within each window, regardless of length, unique launch opportunities will occur 

once every five minutes. 

The first launch opportunity on Nov. 25 is for liftoff at 

10:25 a.m. EST. 

Launch Sequences

The launch time, called “T Zero,” is 1.1 seconds before 

liftoff. Ignition of the Atlas V 541 first-stage common 

core booster is at 2.7 seconds before T Zero, or 3.8 

seconds before liftoff. 

The four solid rocket boosters ignite 3.5 seconds after 

ignition of the common core booster (0.3 second before 

liftoff). They burn for about a minute and a half, and 

then their spent casings are jettisoned in pairs several 

seconds after burnout. 

The common core booster engine of the first stage 

continues to burn until about 4 minutes and 20 seconds 

after liftoff. During that burn, at about 3 minutes and 

25 seconds after liftoff, the payload fairing around the 

spacecraft is jettisoned. The booster engine finishes 

its work at an event called the booster engine cutoff. 

At that point, these engines have consumed about 

623,000 pounds (284,000 kilograms) of propellant in 

less than five minutes and, with the help of the solid 

rocket boosters, taken the spacecraft to an altitude of 
Mars Science Laboratory Launch 27 Press Kit

about 98 miles (158 kilometers) down range from Cape 

Canaveral about 307 miles (494 kilometers). 

After coasting for a few seconds following booster 

engine cutoff, the launch vehicle’s second stage Centaur 

separates from the first stage, which drops into the 

Atlantic Ocean. About 10 seconds after that separation, 

the Centaur engine is started for the first of two burns. 

That burn lasts about 7 minutes and inserts the Centaurand-spacecraft stack into a parking orbit. The shape 

of the parking orbit is an ellipse varying in altitude from 

102 miles (165 kilometers) to 201 miles (324 kilometers). 

However, the spacecraft will not complete even one 

orbit. After completion of the Centaur main engine’s first 

burn (main engine cutoff 1), the stack coasts in the parking orbit until it reaches the proper position for start of the 

second Centaur burn, depending on launch date and 

launch time. This coast lasts 14 to 30 minutes, dependLiftoff

t = 1.1 sec

Solid Rocket Booster Jettison

t = 0:01:52

Alt = 30 miles

Range = 31 miles

V = 3,305 mph

Payload Fairing Jettison

t = 0:03:25

Alt = 74 miles

Range = 158 miles

V = 7,599 mph

Centaur Separation

t = 0:04:27

Alt = 100 miles

Range = 328 miles

V = 12,608 mph Main Engine 

Start 1

t = 0:04:37

Alt = 105 miles

Range = 361 miles

V = 12,582 mph

Main Engine 

Cutoff 1

t = 0:11:30

Orbit altitude = 

102 x 201 miles

Main Engine 

Start 2

t = 0:31:05

Main Engine 

Cutoff 2

t = 0:39:05

Spacecraft

Separation

t = 0:42:48

Trajectory

Interface Point

t = 0:47:48

End of Avoidance 

Maneuver

t = 1:07:38

Centaur

End of Mission

t = 1:50:48

Burn

Duration

0:06:52

Coast

Duration

0:19:35

Burn

Duration

0:08:00

ing on launch timing — about 20 minutes for a launch 

at the initial Nov. 25 opportunity at the opening of the 

launch window.

The second Centaur burn, continuing for nearly 8 minutes (for a launch at the opening of the Nov. 25 launch 

window), lofts the spacecraft out of Earth orbit and on 

its way toward Mars. The burn ends with main engine 

cutoff 2. Three minutes and 43 seconds after that cutoff, 

pyrotechnic actuators and push-off springs on the 

second stage of the Atlas release the spacecraft with 

a separation velocity (relative to the launch vehicle) of 

0.6 miles per hour (0.27 meters per second) and a spin 

rate of about 2.5 rotations per minute. By that point, 

43 minutes after liftoff for the first Nov. 25 opportunity at 

the opening of the launch window, the two stages of the 

Atlas have accelerated the spacecraft to about 22,866 

miles per hour (10.22 kilometers per second) relative to 

Profile of Mars Science Laboratory launch events, for a launch at first opportunity: Nov. 25, 2011, at 10:25 a.m. EST
Mars Science Laboratory Launch 28 Press Kit

Earth. Shortly after that, the separated Centaur performs 

its last task, an avoidance maneuver taking itself out 

of the spacecraft’s flight path to avoid hitting either the 

spacecraft or Mars. 

Throughout the launch sequence, radio transmissions 

from the Atlas to NASA’s Tracking and Data Relay 

Satellite System enable ground controllers to monitor 

critical events and the status of the launch vehicle and 

the spacecraft. The Mars Science Laboratory spacecraft 

cannot begin its own direct transmissions until after it 

separates from the launch vehicle and an antenna on 

the spacecraft is exposed. One minute after spacecraft separation, the flight software transitions the Mars 

Science Laboratory to cruise phase and turns on the 

X-band transmitter. The spacecraft does not start transmitting data until five minutes after that, allowing time for 

warming up the amplifier and configuring the telecommunications system.

The first antenna station of NASA’s Deep Space 

Network to receive communication from the spacecraft 

is near Canberra, Australia. Use of an antenna operated by the private-sector United Space Network on the 

Indian Ocean island nation of Mauritius provides a bonus 

opportunity for earlier establishment of communications 

with the spacecraft.

Data received from the spacecraft in the initial acquisition will provide the first evaluation of the spacecraft’s 

health in cruise mode, including confirmation that the 

cruise-stage solar arrays are producing electricity. Once 

the spacecraft is in a stable state, cruise phase activities 

can begin. 

Interplanetary Cruise and Approach to Mars

The trip from Earth to Mars will take about 36 weeks 

(255 days if launch is at the opening of the launch period 

on Nov. 25, 2011). Most of this period (210 days if 

launch is Nov. 25) is the cruise phase of the mission. 

The final 45 days are the approach phase.

Key activities during cruise include checkouts of the 

spacecraft and its science instruments, tracking of the 

spacecraft, attitude adjustments for changes in pointing of the solar array and antennas, and planning and 

execution of three scheduled maneuvers to adjust the 

spacecraft’s trajectory. Three additional trajectory correction maneuvers are scheduled during the approach 

phase, plus a final, contingency maneuver opportunity, if 

needed.

The Mars Science Laboratory uses what is called a 

Type 1 trajectory to Mars, meaning the spacecraft will 

fly less than halfway around the sun while in transit 

from one planet to the other. 

During cruise and approach, the spacecraft is spinstabilized at two rotations per minute. The attitude of 

the spacecraft’s axis of rotation relative to Earth and the 

sun affects telecommunications, power and thermal 

performance. The plane of the solar array on the cruise 

stage is perpendicular to that axis, and the two antennas used during cruise are pointed in line with that axis, 

in the direction the array faces. The parachute low-gain 

antenna, used during the first two months of the trip 

when the angle between the sun and Earth is relatively large, works at a wider range of pointing angles 

than possible with the medium-gain antenna, which is 

mounted on the cruise stage. As the spacecraft gets 

farther from Earth, the medium-gain antenna is needed 

for providing communication capability used for navigation, so the spacecraft’s attitude must be maintained 

with pointing closer to Earth. The sun will not be in the 

same direction as Earth. To accommodate keeping 

the medium-gain antenna pointed within less than 10 

degrees away from Earth during the later part of the 

cruise and approach, the power and thermal subsystems have been designed to cope with an off-sun 

angle greater than the off-Earth angle.

Thrusters on the cruise stage are fired to adjust the 

spacecraft’s flight path three times during the cruise 

phase and additional times, as needed, during the 

approach phase. The first one is planned for 15 days 

after launch; the second for 120 days after launch. 

These two are used to remove most of the launchday trajectory’s intentional offset from Mars, which is a 

planetary protection precaution to avoid the possibility 

of the launch vehicle’s upper stage reaching Mars without having been cleaned to the standards of a Marslanding spacecraft. The spacecraft spends the first 

two weeks of cruise on a trajectory that would miss 

Mars by hundreds of thousands of miles or kilometers. 

The first two trajectory correction maneuvers direct the 

trajectory closer to Mars, but still leave some off-Mars 

bias as a precaution against the spacecraft hitting Mars 

in a way that could prevent the mission’s planetary 

protection precautions from being effective. The third 

trajectory correction maneuver, about two months after 

the second and 60 days before landing, is the first one 

to actually target the desired Mars atmospheric entry 

point.
Mars Science Laboratory Launch 29 Press Kit

Schematic view of Mars Science Laboratory cruise phase 

from Earth to Mars 

Three additional trajectory maneuvers are scheduled 

during the approach phase, at eight days before landing, two days before landing and nine hours before 

landing. As a precaution in case of any problem with 

the trajectory correction maneuver at two days out, the 

schedule holds a contingency maneuver at 24 hours 

before landing.

Trajectory correction maneuvers combine assessments 

of the spacecraft’s trajectory with calculations of how to 

use the eight thrusters on the cruise stage to alter the 

trajectory. Navigators’ assessments of the spacecraft’s 

trajectory use three types of tracking information from 

ground antennas of NASA’s Deep Space Network in 

California, Spain and Australia. One method is ranging, which measures the distance to the spacecraft by 

timing precisely how long it takes for a radio signal to 

travel to the spacecraft and back. A second is Doppler, 

which measures the spacecraft’s speed relative to Earth 

by the amount of shift in the pitch of a radio signal from 

the craft. A newer method, called delta differential oneway range measurement, adds information about the 

location of the spacecraft in directions perpendicular to 

the line of sight. For this method, pairs of antennas on 

different continents simultaneously receive signals from 

the spacecraft, and then the same antennas observe 

natural radio waves from a known celestial reference 

point, such as a quasar, which serves as a navigation 

reference point.

Six trajectory correction maneuvers (TCMs) are scheduled 

during the voyage from Earth to Mars. Arrival at Mars will be 

Aug. 6, 2012, Universal Time. 
Mars Science Laboratory Launch 30 Press Kit

All of the spacecraft’s science instruments get health 

checks during the cruise phase. One, the Radiation 

Assessment Detector, will be used on a power-available 

basis to collect information about the radiation environment near Earth and between Earth and Mars.

The final five days of the approach phase include activities in preparation for the spacecraft’s atmospheric 

entry, descent and landing. These include preheating of 

some components and enabling others. The schedule 

includes four opportunities to update parameters for the 

autonomous software controlling events during the entry, 

descent and landing. 

Entry, Descent and Landing

The intense period called the entry, descent and landing 

(EDL) phase of the mission begins when the spacecraft 

reaches the Mars atmosphere, traveling at about 13,200 

miles per hour (5,900 meters per second). It ends about 

Cruise Stage Separation

Time: Entry - 10 min

Cruise Balance Devices Separation

Time: Entry - ~8 min

Entry Interface

Altitude: ~78 miles (~125 km)

Velocity: ~13,200 mph (~5,900 meters/sec)

Time: Entry + 0 sec

Peak Heating

Peak 

Deceleration

Hypersonic 

Aero-maneuvering

Parachute Deploy

Altitude: ~7 miles (~11 km)

Velocity: ~900 mph 

(~405 meters/sec)

Time: Entry + ~255 sec

Heat Shield 

Separation

Altitude: ~5 miles (~8 km)

Velocity: ~280 mph 

(~125 meters/sec)

Time: Entry + ~279 sec

Radar Data 

Collection

Back Shell Separation

Altitude: ~1 mile (~1.6 km)

Velocity: ~180 mph 

(~80 meters/sec)

Time: Entry + ~350 sec

Powered 

Descent

Sky Crane

Flyaway

Rover Separation

Altitude: ~66 feet (~20 meters)

Velocity: ~1.7 mph (~0.75 meter/sec)

Time: Entry + ~390 sec

Mobility

Deploy

Flyaway

Altitude: 0

Velocity: ~1.7 mph 

(~0.75 meter/sec)

Time: Entry + ~403 sec

Touchdown

Sky Crane Detail

seven minutes later with the rover and descent stage 

stationary on the surface — one about to begin its 

mission and the other with its job completed.

The top of Mars’ atmosphere is actually a gradual transition to interplanetary space, not a sharp boundary. 

The atmospheric entry interface point — the aim point 

for the flight to Mars — is set at 2,188.6 miles (3,522.2 

kilometers) from the center of Mars. That altitude is 

81.46 miles (131.1 kilometers) above the ground 

elevation of the landing site at Gale Crater, though the 

entry point is not directly above the landing site.

Ten minutes before the spacecraft enters the atmosphere, it sheds the cruise stage. The Mars Science 

Laboratory Entry Descent and Landing Instrument 

(MEDLI) Suite begins taking measurements. The data 

MEDLI provides about the atmosphere and about the 

heat shield’s performance will aid in design of future 

Mars landings. 

Profile of entry, descent and landing events, for one typical case. Exact timing will be determined by atmospheric conditions on 

landing day.
Mars Science Laboratory Launch 31 Press Kit

Beginning a minute later, small thrusters on the back 

shell halt the two-rotation-per-minute spin that the 

spacecraft had maintained during cruise and approach 

phases. Nine minutes before entry, the back shell thrusters orient the spacecraft so the heat shield faces forward, a maneuver called “turn to entry.” 

After the turn to entry, the back shell jettisons two 

solid-tungsten weights, called the “cruise balance mass 

devices.” Ejecting these devices, which weigh about 165 

pounds (75 kilograms) each, shifts the center of mass of 

the spacecraft. During the cruise and approach phases, 

the center of mass is on the axis of the spacecraft’s 

stabilizing spin. Offsetting the center of mass for the 

period during which the spacecraft experiences dynamic 

pressure of interaction with the atmosphere gives the 

Mars Science Laboratory the ability to fly through the 

atmosphere with an angle of attack, generating lift. The 

mission manipulates that lift, using a technique called 

“guided entry,” to steer out unpredictable variations in the 

density of the Mars atmosphere and improve the precision of landing on target.

As the spacecraft interacts with the upper atmosphere, 

small thrusters on the back shell can adjust the angle 

and direction of tilt, enabling the spacecraft to fly a series 

of “S” curves. The S curves reduce the net horizontal distance that the spacecraft covers as it descends. Using 

fewer of them prevents undershooting the target area; 

using more of them prevents overshooting the target 

area. The guided entry maneuvers can also correct for 

net drift to the left or right due to winds. The spacecraft 

autonomously controls the guided entry movements in 

response to information that its gyroscope-containing 

inertial measurement unit provides about deceleration 

and direction, indirect indicators of atmospheric density 

and winds. 

More than nine-tenths of the deceleration before landing 

results from friction with the Mars atmosphere before the 

parachute opens. Peak heating occurs about 80 seconds after atmospheric entry, when the temperature at 

the external surface of the heat shield will be about 3,800 

degrees Fahrenheit (about 2,100 degrees Celsius). Peak 

deceleration occurs about 10 seconds later. 

The span of time from atmospheric entry until touchdown is not predetermined. The exact timing and altitude 

for key events depends on unpredictable factors in 

atmospheric conditions on landing day. The guided entry 

technique enables the spacecraft to be more responsive to unpredictable atmospheric conditions than any 

previous Mars mission. The span between the moment 

the spacecraft passes the entry interface point and a 

successful touchdown in the target area of Gale Crater 

could be as short as about 369 seconds or as long as 

about 460 seconds. Times for the opening of the parachute could vary by 10 to 20 seconds for a successful 

landing. Times given in the following description and on 

the accompanying graphic are for a typical case, with 

touchdown 403 seconds after entry.

After the spacecraft finishes its guided entry maneuvers, 

a few seconds before the parachute is deployed, the 

back shell jettisons another set of tungsten weights to 

shift the center of mass back to the axis of symmetry. 

This set of six weights, the “entry balance mass devices,” each has a mass of about 55 pounds (25 kilograms). Shedding them re-balances the spacecraft for 

the parachute portion of its descent. 

The parachute deploys about 255 seconds after entry, 

at an altitude of about 7 miles (11 kilometers) and a 

velocity of about 900 miles per hour (about 405 meters 

per second). After about 24 more seconds, the heat 

shield separates and drops away when the spacecraft is 

at an altitude of about 5 miles (about 8 kilometers) and 

a velocity of about 280 miles per hour (125 meters per 

second). The Mars Descent Imager begins recording 

video of the ground beneath the spacecraft. The rover, 

with its descent-stage “rocket backpack,” is still attached to the back shell on the parachute. The terminal 

descent sensor, a radar system mounted on the descent 

stage, begins collecting data about velocity and altitude.

The back shell, with parachute attached, separates from 

the descent stage and rover about 80 seconds after 

heat shield separation. At this point, the spacecraft is 

about 0.9 mile (1.4 kilometers) above the ground and 

rushing toward it at about 180 miles per hour (about 80 

meters per second). All eight throttleable retrorockets on 

the descent stage, called Mars landing engines, begin 

firing for the powered descent phase.

After the engines have decelerated the descent to 

about 1.7 miles per hour (0.75 meters per second), the 

descent stage maintains that velocity until rover touchdown. Four of the eight engines shut off just before nylon 

cords begin to spool out to lower the rover from the 

descent stage in the “sky crane” maneuver. The rover 

separates its hard attachment to the descent stage, 

though still attached by the sky crane bridle, at an altitude of about 66 feet (about 20 meters), with about 12 

seconds to go before touchdown.
Mars Science Laboratory Launch 32 Press Kit

The rover’s wheels and suspension system, which 

double as the landing gear, pop into place just before 

touchdown. The bridle is fully spooled out as the spacecraft continues to descend, so touchdown occurs at the 

descent speed of about 1.7 miles per hour (0.75 meters 

per second). When the spacecraft senses touchdown, 

the connecting cords are severed and the descent 

stage flies out of the way, coming to the surface at least 

492 feet (150 meters) from the rover’s position, probably 

more than double that distance.

The rover’s computer switches from entry, descent and 

landing mode to surface mode. This initiates autonomous activities for the first Martian day on the surface 

of Mars, Sol 0. The time of day at the landing site is mid 

afternoon — about 3 p.m. local mean solar time at Gale 

Crater.

Mars Surface Operations

The planned operational life for the Mars Science 

Laboratory is one Martian year on the surface. One 

Martian year is 687 Earth days, or 669 Martian days, 

which are called sols. Each sol is 24 hours, 39 minutes, 

35.244 seconds long. The landing site is in an equatorial region, at 4.5 degrees south latitude. The season in 

Mars’ southern hemisphere at the beginning and end of 

the prime mission is late winter, about two thirds of the 

way from winter solstice to spring equinox.

One Martian year is how long the scientists and engineers operating the rover will have to achieve the 

mission’s science goals. Adding to the challenge, some 

periods of the mission will not be fully available for science tasks. These include an initial health checkout for 

about 10 sols or more after landing and about 20 sols 

in April 2013 when communications will be restricted 

due to Mars’ position nearly behind the sun from Earth. 

Strategies for maximizing the science accomplishments 

in the time available include extensive preparations 

before landing, efficiently coordinated use of the rover’s 

capabilities and flexibility for responding to discoveries. 

The structure of science activities is based on sending 

a set of commands to the rover each Martian morning 

for the activities to be performed during that sol. The 

activity plan for the sol needs to fit within the constraints 

of time, power, temperature factors and data volume for 

the sol. During a communication relay opportunity when 

an orbiter passes overhead in the Martian midafternoon, 

the rover transmits data about the sol’s activities. Any of 

the sol’s results that will influence the next sol’s activities 

need to be included in this downlink, though additional 

data from the sol can be transmitted during later relay 

opportunities.

With data from preceding sols, the rover team needs to 

make decisions for each sol, such as what targets to approach, what instruments to use, what observations to 

make and what downlink priority level to assign for each 

set of data generated during the sol or stored onboard 

from earlier sols. The rover team’s engineers collaborate 

with scientists to determine what activities are safe and 

feasible, and to develop and check the sequences of 

commands for transmission to the rover. 

In initial weeks of Mars surface operations, the team will 

work on a Mars time schedule to make best use of the 

key hours between when one sol’s downlink is received 

and when the next sol’s commands must be ready, 

whatever time of day that is at the operations center 

at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. 

Team members’ work shift will begin about 40 minutes 

later each day than on the preceding day because a 

sol is that much longer than an Earth day. Later in the 

mission, operations will transition to an Earth-day work 

schedule and will become more geographically distributed as non-Pasadena team members return to their 

home institutions and participate through teleconferencing.

The landing sol is designated as Sol 0, a change from 

the practice of the Mars Exploration Rover missions, 

which designated landing sols of Spirit and Opportunity 

as Sol 1. On Curiosity’s Sol 0, the information expected 

from the rover will confirm its status after landing. 

Additional information about rover health and status may 

come about 12 hours after landing via relay from the 

Mars Reconnaissance Orbiter passing over the landing 

site at about 3 a.m. local Mars time on Sol 1.

Priority activities for Sol 1, built into command sequences stored onboard from before landing, are to raise the 

camera mast, image the sky with the navigation camera, 

determine the location of the sun from those images, 

calculate the angle toward Earth, then point the highgain antenna toward Earth.

Activities over the next few sols will characterize the rover 

and landing site by conducting health checks of various 

rover subsystems, completing a color panorama from 

the Mastcam and taking weather measurements. The 

first drive may be more than a week after landing, and 
Mars Science Laboratory Launch 33 Press Kit

the first use of the robotic arm will probably be after the 

first drive. 

After completion of the characterization activities, the 

pace of driving and the frequency of multi-sol stops for 

acquiring and analyzing rock or soil samples will be determined by the team decisions about science priorities. 

Some possible destinations identified in advance from 

orbit may be within several weeks of driving distance 

from the landing site. With the time taken to investigate 

nearer stopping points, other likely destinations are more 

than a year away.

Communications Strategy

Like all of NASA’s interplanetary missions, the Mars 

Science Laboratory will rely on the agency’s Deep 

Space Network to communicate with the spacecraft 

and to track it during flight. The network has groups of 

antennas at three locations: at Goldstone in California’s 

Mojave Desert; near Madrid, Spain; and near Canberra, 

Australia. These locations are about one-third of the way 

around the world from each other. That assures, whatever time of day it is on Earth, at least one of them will have 

the spacecraft in view during its trip from Earth through 

landing. At least one location will have Mars in view at 

any time during the rover’s Mars-surface operations. 

Each complex is equipped with one antenna 230 feet 

(70 meters) in diameter, at least two antennas 112 feet 

(34 meters) in diameter, and smaller antennas. All three 

complexes communicate directly with the control hub at 

NASA’s Jet Propulsion Laboratory, Pasadena, Calif. 

As the spacecraft travels from Earth to Mars during the 

cruise and approach phases of the mission it communicates directly with Earth in the X-band portion of the 

radio spectrum (at 7 to 8 gigahertz). For this, the spacecraft uses a transponder and amplifier in the spacecraft’s 

descent stage and two antennas. One of the antennas, 

the parachute low-gain antenna, is on the aeroshell’s 

parachute cone, which is exposed through the center of 

the cruise stage. The other, the medium-gain antenna, 

is mounted on the cruise stage. The parachute low-gain 

antenna serves during the early weeks of the cruise to 

Mars, then again during cruise-stage separation. During 

most of the voyage, the job switches to the medium-gain 

antenna, which provides higher data rates but requires 

more restrictive pointing toward Earth. The telecommunications system provides position and velocity information 

for navigation, as well carrying data and commands.

Communication during atmospheric entry, descent 

and landing is a high priority. Landings on Mars are 

notoriously difficult. If this landing were not successful, 

maintaining communications during the entry, descent 

and landing would provide critical diagnostic information 

that could influence the design of future missions.

All three orbiters currently active at Mars — NASA’s 

Mars Odyssey and Mars Reconnaissance Orbiter and 

the European Space Agency’s Mars Express — will 

be at positions where they can receive transmissions 

from the Mars Science Laboratory spacecraft during its 

entry, descent and landing. These transmissions to the 

orbiters use the ultra-high frequency (UHF) portion of 

the radio spectrum (at about 400 megahertz) from three 

different UHF antennas. The parachute UHF antenna, 

mounted on the back shell, transmits information from 

a few minutes before atmospheric entry until the rover 

and descent stage separate from the back shell. At 

that point, the descent UHF antenna on the descent 

stage takes over. When the rover drops away from the 

descent stage on its sky-crane bridle, the rover UHF antenna is exposed to begin transmissions that continue 

through landing. The orbiters relay to Earth via X band 

the information they receive from the Mars Science 

Laboratory during this critical period.

The Mars Science Laboratory spacecraft will also 

transmit in X band during its entry, descent and landing. Due to signal strength constraints, these transmissions will be simple semaphore codes rather than full 

telemetry. The Deep Space Network will listen for those 

direct-to-Earth transmissions. The X-band antenna in 

use at the start of atmospheric entry is the parachute 

low-gain antenna on the back shell. Transmissions are 

shifted to the tilted low-gain antenna, also on the back 

shell, before the start of the banking maneuvers of the 

guided entry. After the separation of the back shell, the 

descent low-gain antenna, mounted on the descent 

stage, handles X-band transmission. The rover low-gain 

antenna transmits in X band, but not until after landing. 

During Mars surface operations, the rover Curiosity has 

multiple options available for receiving commands from 

mission controllers on Earth and for returning rover science and engineering information. 

Curiosity has the capability to communicate directly with 

Earth via X-band links with the Deep Space Network. 

This capability will be used routinely to deliver commands to the rover each morning on Mars. It can also 

be used to return information to Earth, but only at 
Mars Science Laboratory Launch 34 Press Kit

relatively low data rates — on the order of kilobits per 

second — due to the rover’s limited power and antenna 

size, and to the long distance between Earth and Mars.

Curiosity will return most information via UHF relay links, using one of its two redundant Electra-Lite 

radios to communicate with a Mars orbiter passing 

overhead. In their trajectories around Mars, the Mars 

Reconnaissance Orbiter and Mars Odyssey orbiter 

each fly over the Curiosity landing site at least once 

each afternoon and once each morning before dawn. 

While these contact opportunities are short in duration, 

typically lasting only about 10 minutes, the proximity of 

the orbiters allows Curiosity to transmit at much higher 

data rates than the rover can use for direct-to-Earth 

transmissions. The rover can transmit to Odyssey at 

up to about 0.25 megabit per second and to the Mars 

Reconnaissance Orbiter at up to about 2 megabits per 

second. The orbiters, with their higher-power transmitters and larger antennas, then take the job of relaying 

the information via X-band to the Deep Space Network 

on Earth. Mission plans call for the return of 250 megabits of Curiosity data per Martian day over these relay 

links. The links can also be used for delivering commands from Earth to Curiosity.

While not planned for routine operational use during Curiosity’s surface mission, the European Space 

Agency’s Mars Express orbiter will be available as a 

backup communications relay asset should NASA’s 

relay orbiters become unavailable for any period of time.

Planetary Protection

When sending missions to Mars, precautions must be 

taken to avoid introduction of microbes from Earth by 

robotic spacecraft. This is consistent with United States 

obligations under the 1967 Outer Space Treaty, the 

international treaty stipulating that exploration must be 

conducted in a manner that avoids harmful contamination of celestial bodies. “Planetary protection” is the 

discipline responsible for the development of rules and 

practices used to avoid biological contamination in the 

process of exploration. NASA has a planetary protection officer responsible for establishing and enforcing 

planetary protection regulations. Each spacecraft mission is responsible for implementing measures to comply with the regulations. In compliance with the treaty 

and NASA regulations, the Mars Science Laboratory 

flight hardware has been designed and built to meet 

planetary protection requirements.

NASA’s primary strategy for preventing contamination of Mars with Earth organisms is to be sure that all 

hardware going to the planet is biologically clean. The 

Mars Science Laboratory mission is allowed to carry up 

to 500,000 bacterial spores on the entire flight system. 

That’s about one tenth as many as in a typical teaspoon 

of seawater. Spore-forming bacteria have been the 

focus of planetary protection standards because these 

bacteria can survive harsh conditions for many years as 

inactive spores. One requirement for this mission is that 

the exposed interior and exterior surfaces of the landed 

system, which includes the rover, parachute and back 

shell, must not carry a total number of bacterial spores 

greater than 300,000, with the average spore density 

not exceeding 300 spores per square meter (about 11 

square feet). This ensures that the biological load is not 

concentrated in one place. The heat shield and descent 

stage will hit the ground hard enough that hardware 

could break open. The number of spores inside this 

hardware that could be exposed by the hard landings 

of these components must be included in the 500,000 

maximum number. 

The two primary methods used for reducing the number 

of spores on the spacecraft are alcohol wipe cleaning and dry heat microbial reduction. Technicians and 

engineers assembling the spacecraft and preparing it for 

launch have routinely cleaned surfaces by wiping them 

with alcohol and other solvents. Components tolerant of 

high temperature were heated to reduce spore burden 

according to NASA specification, at temperatures ranging from 230 to 295 degrees Fahrenheit (110 to 146 

degrees Celsius) for durations up to 144 hours. The 

planetary protection team carefully samples the surfaces 

and performs microbiological tests to demonstrate that 

the spacecraft meets requirements for biological cleanliness.

The Mars Science Laboratory is also complying with a 

requirement to avoid going to any site on Mars known to 

have water or water-ice within 3.3 feet (one meter) of the 

surface. This is a precaution against any landing-day accident that could introduce hardware not fully sterilized 

by dry heat into an environment where heat from the 

mission’s radioisotope thermoelectric generator and a 

Martian water source could provide conditions favorable 

for microbes from Earth to grow on Mars. 

Another way of making sure the mission does not transport Earth life to Mars is to ensure that any hardware not 

meeting cleanliness standards does not go to Mars ac-
Mars Science Laboratory Launch 35 Press Kit

cidentally. When the Atlas launch vehicle’s upper stage 

Centaur separates from the spacecraft, the two objects 

are traveling on nearly identical trajectories. To prevent 

the possibility of the Centaur hitting Mars, that shared 

flight path is deliberately set so that the spacecraft 

would miss Mars if not for later maneuvers to adjust 

its trajectory. By design, the Centaur is never aimed at 

Mars. 

Portions of the flight hardware will impact the surface of 

Mars as part of a normal landing event. This impact may 

cause the hardware to split open and potentially release 

spores trapped inside the hardware during manufacturing processes. To ensure MSL does not exceed the 

spore allocation, studies were conducted on various 

materials, including paint, propellants and adhesives, to 

determine the number of spores in a given volume. In 

many cases the parts of the spacecraft containing these 

materials used dry heat microbial reduction to reduce 

the number of spores. For hardware expected to impact 

Mars, such as the cruise stage after its separation from 

the aeroshell, a detailed thermal analysis was conducted 

to make sure that plunging through Mars’ atmosphere 

creates enough heat that few to no spores survive.
Mars Science Laboratory Launch 36 Press Kit

Comparing Two Mars Rover Projects

Rovers 1 (Curiosity) 2 (Spirit and Opportunity)

Launch vehicle Atlas V Delta II

Heat shield diameter 14.8 feet (4.5 meters) 8.7 feet (2.65 meters)

Design mission life on Mars 1 Mars year (98 weeks) 90 Mars sols (13 weeks)

Science Payload 10 instruments, 165 pounds 5 instruments, 11 pounds 

 (75 kilograms) (5 kilograms)

Rover mass 1,982 pounds (899 kilograms) 374 pounds (170 kilograms)

Rover size (excluding arm) Length 10 feet (3 meters); Length 5.2 feet (1.6 meters);

 width 9 feet (2.7 meters); width 7.5 feet (2.3 meters); 

 height 7 feet (2.2 meters) height 4.9 feet (1.5 meters)

Robotic arm 7 feet (2.1 meters) long, 2.5 feet (0.8 meter) long, 

 deploys two instruments, deploys three instruments, 

collects powdered samples removes surfaces of rocks, 

 from rocks, scoops soil, prepares brushes surfaces

 and delivers samples for analytic

instruments, brushes surfaces 

Entry, descent and landing Guided entry, sky crane Ballistic entry, air bags

Landing ellipse 15.5 miles (25 kilometers) long 50 miles (80 kilometers) long

(99-percent confidence area)

Power supply on Mars Multi-mission radioisotope Solar photovoltaic panels 

 thermoelectric generator (less than 1,000 watt hours per sol)

 (about 2,700 watt hours per sol) 

Computer Redundant pair, 200 megahertz, Single, 20 megahertz,

 250 MB of RAM, 2 GB of 128 MB of RAM, 256 MB of 

 flash memory flash memory

Mars Science Laboratory Mars Exploration Rovers
Mars Science Laboratory Launch 37 Press Kit

The Mars Science Laboratory spacecraft consists of 

four major elements: rover, descent stage, aeroshell 

and cruise stage. The rover, Curiosity, has the science 

payload and systems that enable the rover to use the 

payload effectively and send home the results. The 

descent stage performs the final moments of delivering 

the rover to the surface of Mars. The aeroshell, which 

includes the heat shield and the back shell, provides 

thermal protection and maneuverable lift during the initial 

portion of descent through the Martian atmosphere, and 

then a parachute ride for the next portion of the descent. 

The cruise stage provides trajectory maneuvers, electrical power, communications and other functions during 

the eight months from launch to landing.

Cruise Stage

The cruise stage is doughnut-shaped, about five times 

wider than it is tall, with 10 radiators arranged around 

the perimeter. The hole of the doughnut sits over a cone 

holding the parachute on top of the aeroshell. One surface of the cruise stage attaches to the launch vehicle. 

That attachment is severed within the first hour after 

launch. The other surface of the cruise stage attaches 

to the top of the aeroshell. That attachment is severed 

10 minutes before the spacecraft enters Mars’ atmosphere. During the roughly eight months between those 

Back Shell 

Interface Plate

Parachute Support 

Structure

Parachute

Bridle 

Umbilical

Device

Cruise Stage

Back Shell

Descent Stage

Rover

Heat Shield

Entry

Vehicle

System

two separation events (232 to 260 days, depending on 

launch date), the cruise stage performs essential tasks 

of the flight, though it uses the computer inside the 

rover.

The cruise stage primary structure is aluminum. An inner ring connects to the launch vehicle interface and the 

back shell interface plate. A series of ribs connect other 

components. The cruise propulsion system is used to 

maintain the spacecraft’s spin rate, adjust the spacecraft’s orientation, and provide propulsion for trajectory 

correction maneuvers scheduled into the trip between 

Earth and Mars. Two clusters of thrusters each include 

four thruster engines in different orientations enabling 

different directions of thrust. Each of the eight thrusters can provide about 1.1 pounds (5 newtons) of force. 

They use hydrazine, a monopropellant that does not require an oxygen source. Hydrazine is a corrosive liquid 

compound of nitrogen and hydrogen that decomposes 

explosively into expanding gases when exposed to a 

catalyst in the thrusters. Two spherical propellant tanks 

on the cruise stage, each 19 inches (48 centimeters) 

in diameter, supply the pressurized propellant. Aerojet 

built the thrusters at its Redmond, Wash., facility. On 

both the cruise stage and descent stage, fuel tanks are 

from ATK Space Systems, Inc., Commerce, Calif.; and 

pressurant tanks are from Arde, Inc., Carlstadt, N.J.

Mars Science Laboratory flight system, expanded view

Spacecraft
Mars Science Laboratory Launch 38 Press Kit

The spacecraft spins at two rotations per minute for 

stability on its way to Mars. The cruise stage monitors 

the spin rate and the spacecraft’s attitude (orientation) 

with a star scanner and one of two sun sensor assemblies. Each of the sun sensor assemblies, from Adcole 

Corp., Marlborough, Mass., includes four sun-sensor 

heads pointing in different directions. Based on star 

tracking and sun sensing information, the cruise stage 

uses its thrusters as necessary to maintain the spin rate 

and attitude. 

Most of the electrical power for the spacecraft during the 

trip from Earth to Mars is provided by sunshine hitting a 

ring-shaped array of photovoltaic cells on the upper surface of the cruise stage. The Multi Mission Radioisotope 

Thermoelectric Generator on the rover supplements 

the electricity provided by the cruise solar array on the 

way to Mars. The solar array has six physical panels 

totaling 138 square feet (12.8 square meters) of active 

photovoltaic area. The photovoltaic cells from Emcore 

Corp., Albuquerque, N.M., use layers of three different 

materials to gain electricity from different portions of the 

solar spectrum. The layers are gallium indium phosphorus, gallium arsenide and germanium. If operated at full 

capacity at Earth, the array could produce about 2,500 

watts, which would exceed the spacecraft’s needs. 

The array and its operation are designed to satisfy the 

mission’s requirements from launch day to the Mars approach. At its farthest from the sun, during the approach 

to Mars, the array will produce 1,080 watts or more, 

even when facing as much as 43 degrees away from 

the sun. 

Another important function for the cruise stage is to 

maintain temperatures within designed ranges for the 

parts of the spacecraft inside the aeroshell as well as 

for the cruise stage itself. The 10 radiators of the heatrejection system are mounted as a ring around the 

outer edge of the cruise stage. Fluid pumped through a 

circulatory system disperses heat from the rover’s multimission radioisotope thermoelectric generator to warm 

the electronics of the cruise stage and to be released 

into space by the radiators.

The medium-gain antenna mounted on the cruise stage 

serves in telecommunications with Earth during most of 

the trip from Earth to Mars. 

 

Aeroshell

The aeroshell that encapsulates the rover and descent 

stage during the flight to Mars protects them from 

friction with Mars’ atmosphere and provides other 

functions. 

The Mars Science Laboratory aeroshell is not only the 

biggest ever built for a planetary mission, but also incorporates major innovations in attitude control for guided 

entry and in thermal protection material. Lockheed 

Martin Space Systems, Denver, built the areoshell’s heat 

shield and back shell.

The diameter of the heat shield is 14.8 feet (4.5 meters). 

For comparison, heat shields of the Apollo capsules 

that returned astronauts to Earth after visits to the moon 

were just under 13 feet (4 meters) in diameter, and the 

heat shields for the Mars Exploration Rovers, Spirit and 

Opportunity, were 8.7 feet (2.65 meters). 

This aeroshell, unlike any predecessor for an extraterrestrial mission, has a steering capability. This is a key 

to the mission’s guided entry innovation for added 

precision in landing. During a crucial portion of descent 

through the upper atmosphere of Mars, before the back 

shell deploys its parachute, the center of mass of the 

spacecraft will be offset from the axis of symmetry (a 

line through the center of the aeroshell). This offset puts 

the aeroshell at an angle to its direction of movement, 

creating lift as the spacecraft interacts with the atmosphere. With lift, the spacecraft can fly like a wing, rather 

than dropping like a rock. A reaction control system with 

small thrusters to adjust the orientation of the spacecraft 

can steer banking turns. A series of turns can shorten 

the net horizontal distance the spacecraft covers during 

its descent. Performed in response to sensing how the 

spacecraft is reacting to unpredictable variability in the 

atmosphere, the maneuvers counteract the unpredictability and provide a more precise landing.

The heat shield uses a different thermal protection 

system than used on earlier Mars missions’ heat 

shields, because the unique entry trajectory profile and 

the mass and size of the vehicle could create external 

temperatures up to 3,800 degrees Fahrenheit (about 

2,100 degrees Celsius). The heat shield is covered with 

tiles of phenolic impregnated carbon ablator (PICA) 

material. NASA Ames Research Center, Moffett Field, 

Calif., invented the PICA material; Fiber Materials Inc., 

Biddeford, Maine, made the tiles. PICA was first flown 

as the thermal protection system on the heat shield of 

NASA’s Stardust Sample Return Capsule.

The heat shield carries sensors for collecting data about 

Mars’ atmosphere and the performance of the heat 
Mars Science Laboratory Launch 39 Press Kit

shield. These are part of the Mars Science Laboratory 

Entry, Descent and Landing Instrument (MEDLI) Suite, 

which is described in the Mars Science Laboratory 

Investigations section of this document. 

The back shell, besides making up the upper portion of 

the capsule protecting the rover during passage through 

Mars’ atmosphere, includes several devices used during 

the spacecraft’s atmospheric entry and descent. 

The back shell carries two sets of detachable tungsten 

weights for altering the spacecraft’s center of mass.

Eight small thrusters in the upper half of the back shell 

are used for the guided entry maneuvers. 

A conical structure at the top of the back shell holds 

the parachute and its deployment mechanism. The 

parachute is the largest ever built for an extraterrestrial 

mission. It uses a configuration called disk-gap-band. It 

has 80 suspension lines, measures 165 feet (50 meters) 

in length, and opens to a diameter of 51 feet (nearly 16 

meters). Most of the orange and white fabric is nylon, 

though a small disk of heavier polyester is used near the 

vent in the apex of the canopy due to higher stresses 

there. The parachute is designed to survive deployment 

at up to Mach 2.2 in the Martian atmosphere and drag 

forces of up to 65,000 pounds. Pioneer Aerospace 

Corp., South Windsor, Conn., made the parachute.

Mounted on the back shell are two antennas — the 

parachute low-gain antenna and the tilted low-gain 

antenna — for communicating directly with Earth using 

X-band frequencies and another antenna — the parachute UHF antenna — for communicating with Mars 

orbiters using an ultra-high frequency (UHF) band. 

Descent Stage

The descent stage of the Mars Science Laboratory does 

its main work during the final few minutes before touchdown on Mars. It provides rocket-powered deceleration 

and two bands of telecommunications for a phase of the 

arrival at Mars after the phases using the heat shield and 

parachute. After reaching a constant vertical velocity, the 

descent stage lowers the rover on a bridle and continues 

descent until rover touchdown. 

The descent stage uses eight rockets, called Mars lander engines (MLE), positioned around its perimeter in four 

pairs. These are the first throttleable engines for a Mars 

landing since the Mars Viking landings in 1976. They 

were built by Aerojet, in Richmond, Wash., with throttle 

valve assemblies from Moog Inc., East Aurora, N.Y. Each 

can provide an adjustable amount of thrust up to about 

742 pounds (3,300 newtons). The propulsion system 

of the descent stage uses pressurized propellant. Three 

spherical fuel tanks provide a usable propellant load of 

about 853 pounds (about 387 kilograms) of hydrazine, 

a propellant that does not require an oxygen source. 

Two spherical tanks of pressurized helium provide pressure for propellant delivery, moderated by a mechanical 

regulator. 

While the rover is fastened to the descent stage, the two 

components together are called the powered descent 

vehicle. The fastenings are pyrotechnic bolts. Firing to 

release these connections commences the spacecraft’s 

sky crane maneuver.

To perform the sky crane maneuver of lowering the 

rover on a bridle, the descent stage carries a device 

called the bridle umbilical and descent rate limiter (BUD). 

This cone-shaped device is about 2 feet (two-thirds of 

a meter) long. Three tethers of the bridle, attached to 

the rover at three points, are spooled around the BUD, 

with enough length to lower the rover about 25 feet (7.5 

meters) below the descent stage during the sky crane 

maneuver. A slightly longer umbilical, with data and 

power connections between the rover and the descent 

stage, is also spooled around the BUD. A descent brake 

in the device governs the rotation rate as the bridle unspools, hence the speed at which gravity pulls the rover 

away from the descent stage. The descent brake, made 

by the Starsys division of SpaceDev Inc. (now Sierra 

Nevada Corp.), Poway, Calif., uses gear boxes and 

banks of mechanical resistors engineered to prevent the 

bridle from spooling out too quickly or too slowly. The 

cords of the bridle are made of nylon. The BUD also includes springs for quickly retracting the loose bridle and 

umbilical after they are severed at the rover end when 

touchdown is detected.

Through the umbilical, the spacecraft’s main computer 

inside the rover controls activities during the entry, 

descent and landing. After the heat shield drops away, 

crucial information for determining the timing of events 

comes to that computer from the terminal descent 

sensor, a radar system engineered and built specifically 

for this mission. The radar, mounted on the descent 

stage, has six disk-shaped antennas oriented at different 

angles. It measures both vertical and horizontal velocity, 

as well as altitude.
Mars Science Laboratory Launch 40 Press Kit

The descent stage carries an X-band transponder and 

amplifier and two telecommunication antennas: the descent low-gain antenna for communicating directly with 

Earth via X-band transmissions and the descent UHF 

antenna for sending information to Mars orbiters. 

Rover

The Mars Science Laboratory rover, Curiosity, carries the 

instruments of the mission’s 10 science investigations 

plus multiple systems that enable the science payload 

to do its job and send home the results. Key systems 

include six-wheeled mobility, sample acquisition and 

handling with a robotic arm, navigation using stereo imaging, a radioisotope power source, avionics, software, 

telecommunications and thermal control. 

The rover’s name was suggested by the winning entrant in a national naming contest conducted among 

U.S. school students. More than 9,000 students, 

ages 5 through 18, submitted entries in late 2008 and 

early 2009. An essay by Clara Ma of Lenexa, Kans., a 

12-year-old sixth-grader at the time, was selected by 

NASA in May 2009. 

Curiosity is 10 feet (3 meters) long (not counting its arm), 

9 feet (2.7 meters) wide and 7 feet (2.2 meters) high at 

the top of its mast, with a mass of 1,982 pounds (899 

kilograms), including 165 pounds (75 kilograms) of science instruments. By comparison, each of the previous 

generation of Mars rovers, Spirit and Opportunity, is 

5.2 feet (1.6 meters) long, 7.5 feet (2.3 meters) wide and 

4.9 feet (1.5 meters) high, with a mass of 374 pounds 

(170 kilograms), including about 20 pounds (9 kilograms) 

of science instruments.

The science payload is described in the Mars Science 

Laboratory Science Investigations section of this press 

kit.

Curiosity’s mechanical structure provides the basis for 

integrating all of the other rover subsystems and payload instruments. The chassis is the core of the rover. 

With insulated surfaces, it forms the shell of the warm 

electronics box containing the avionics. The mechanical subsystem provides deployments that bring the 

rover to its full functionality, including deployments of the 

remote-sensing mast, robotic arm, antennas and mobility system.

Rover Mobility

Curiosity’s mobility subsystem is a scaled-up version 

of what was used on the three earlier Mars rovers: 

Sojourner, Spirit and Opportunity. Six wheels all have 

driver motors. The four corner wheels all have steering 

motors. Each front and rear wheel can be independently 

steered, allowing the vehicle to turn in place as well as to 

drive in arcs. The suspension is a rocker-bogie system. 

Combined with a differential connecting the left and right 

sides of the mobility system, the rocker-bogie design enables a six-wheel vehicle to keep all its wheels in contact 

with the ground even on uneven terrain, such as with a 

wheel going over a rock as big as the wheel. On each 

side, a bogie connects the middle and rear wheels and 

provides a pivot point between those wheels. The rocker 

connects the bogie pivot point to the front wheel. The 

rocker’s pivot point connects to the differential across the 

rover body to the rocker on the other side.

Curiosity’s wheels are aluminum, 20 inches (0.5 meter) 

in diameter, which is twice the size of the wheels on 

Spirit and Opportunity. They have cleats for traction 

and for structural support. Curving titanium spokes 

give springy support. The wheels were machined by 

Tapemation, Scotts Valley, Calif. Titanium tubing for 

the suspension system came from Litespeed Titanium, 

Chattanooga, Tenn. 

The drive actuators — each combining an electric motor and gearbox — are geared for torque, not speed. 

Aeroflex Inc., Plainview, N.Y., built the cold-tolerant actuators for the wheels and other moving parts of Curiosity. 

The rover has a top speed on flat, hard ground of about 

1.5 inches (4 centimeters) per second. However, under 

autonomous control with hazard avoidance, the vehicle 

achieves an average speed of less than half that. The 

rover was designed and built to be capable of driving 

more than 12 miles (more than 20 kilometers) during the 

prime mission. The actual odometry will depend on decisions the science team makes about allocating time for 

driving and time for investigating sites along the way. 

For Curiosity, unlike earlier Mars rovers, the mobility 

system doubles as a landing system, directly absorbing 

the force of impacting the Martian surface at touchdown. 

As on the earlier rovers, the mobility system can also be 

used for digging beneath the surface by rotating one corner wheel while keeping the other five wheels immobile.
Mars Science Laboratory Launch 41 Press Kit

RLGA

Antenna

High Gain

Antenna

DAN

Mobility System

RAD

MARDI

Turret

Robotic Arm

REMS

Mastcam

ChemCam RUHF Antenna

MMRTG

(CheMin, SAM inside the rover)

Curiosity Mars Rover

Locations of several science instruments and major subsystems on the NASA Mars rover Curiosity are indicated. These 

include (clockwise from left): Rover Environmental Monitoring 

Station (REMS); Mast Camera (Mastcam); Chemistry and 

Camera (ChemCam); Rover ultra high-frequency (RUHF) 

antenna; Multi-mission radioisotope thermoelectric generator 

(MMRTG); Rover low-gain (RLGA) antenna; high-gain antenna; Dynamic Albedo of Neutrons (DAN); mobility system 

(wheels and suspension); Radiation Assessment Detector 

(RAD); Mars Descent Imager (MARDI); turret (see larger 

image for tools on the turret at the end of the robotic arm); 

and robotic arm. Two science instruments — Chemistry and 

Mineralogy (CheMin) and Sample Analysis at Mars (SAM) — 

are inside the body of the rover. 

Rover Arm and Turret 

The turret at the end of the Curiosity’s robotic arm holds 

two science instruments and three other devices. The 

arm places and holds turret-mounted tools on rock and 

soil targets and manipulates the sample-processing 

mechanisms on the turret. It is strong enough to hold 

the 73-pound (33-kilogram) turret at full extension of the 

arm. With the arm extended straight forward, the center 

of the turret is 6.2 feet (1.9 meters) from the front of the 

rover body. The diameter of the turret, including the 

tools mounted on it, is nearly 2 feet (60 centimeters).

The arm has five degrees of freedom of movement 

provided by rotary actuators known as the shoulder 

azimuth joint, shoulder elevation joint, elbow joint, 

wrist joint and turret joint. The Space Division of MDA 

Information Systems Inc. built the arm in Pasadena, 

Calif.
Mars Science Laboratory Launch 42 Press Kit

The science instruments on the arm’s turret are the 

Mars Hand Lens Imager (MAHLI) and the Alpha Particle 

X-ray Spectrometer (APXS). The other tools on the turret are components of the rover’s Sample Acquisition/

Sample Processing and Handling (SA/SPaH) subsystem: the Powder Acquisition Drill System (PADS), 

the Dust Removal Tool (DRT), and the Collection and 

Handling for In-situ Martian Rock Analysis (CHIMRA) 

device. 

The Powder Acquisition Drill System is a rotary percussive drill to acquire samples of rock material for analysis. 

It can collect a sample from up to 2 inches (5 centimeters) beneath a rock’s surface. The diameter of the 

Drill

APXS

CHIMRA

DRT

MAHLI

Turret of tools at the end of Curiosity’s robotic arm

Locations of tools on the turret that is mounted on Curiosity’s 

arm are indicated. These include (clockwise from upper 

left): the drill for acquiring powdered samples from interiors 

of rocks; the Alpha Particle X-ray Spectrometer (APXS); 

the sample processing subsystem named Collection and 

Handling for In-Situ Martian Rock Analysis (CHIMRA), 

which includes a scoop for acquiring soil samples; the Dust 

Removal Tool (DRT) for brushing rock surfaces clean; and the 

Mars Hand Lens Imager (MAHLI). 

drilled hole is 0.63 inch (1.6 centimeters). The drill penetrates the rock and powders the sample to the appropriate grain size for use in the two analytical instruments 

inside the rover: Sample Analysis at Mars (SAM), and 

Chemistry and Mineralogy (CheMin). The powder travels 

up an auger in the drill for transfer to sample processing mechanisms. If the drill bit becomes stuck in a rock, 

the drill can disengage from that bit and replace it with 

a spare. The arm moves the drill to engage and capture 

one of two spare bits in bit boxes mounted to the front 

of the rover.

The Dust Removal Tool, from Honeybee Robotics, N.Y., 

is a metal-bristle brushing device used to remove the 
Mars Science Laboratory Launch 43 Press Kit

dust layer from a rock surface or to clean the rover’s 

observation tray. 

One portion of the Collection and Handling for In-situ 

Rock Analysis device is a motorized, clamshell-shaped 

scoop to collect soil samples from the Martian surface. 

The other turret-mounted portion of this device has 

chambers and labyrinths used for sorting, sieving and 

portioning the samples collected by the drill and the 

scoop. These functions are carried out by manipulating 

the orientation of the turret while a vibration device helps 

move material through the chambers, passages and 

sieves. Samples can be sieved to screen out particles 

more than 0.04 inch (1 millimeter) across or to screen 

out particles more than 0.006 inch (150 microns) across. 

The vibration device also aids in creating the appropriate portion size and in the delivery action when the 

device drops material into inlet ports of the analytical 

instruments. Each of the inlet ports — two for Sample 

Analysis at Mars and one for Chemistry and Mineralogy 

— has a cover that can be opened and closed using a 

motor. 

An observation tray on the rover allows the Mars Hand 

Lens Imager and the Alpha Particle X-ray Spectrometer 

a place to examine collected and processed samples of 

soil and powdered rock. 

Rover Power

Rover power is provided by a multi-mission radioisotope 

thermoelectric generator (MMRTG) supplied by the U.S. 

Department of Energy. This generator is essentially a 

nuclear battery that reliably converts heat into electricity. It consists of two major elements: a heat source that 

contains plutonium-238 dioxide and a set of solid-state 

thermocouples that convert the plutonium’s heat energy 

to electricity. It contains 10.6 pounds (4.8 kilograms) of 

plutonium dioxide as the source of the steady supply 

of heat used to produce the onboard electricity and to 

warm the rover’s systems during the frigid Martian night.

Radioisotope thermoelectric generators have enabled 

NASA to explore the solar system for many years. The 

Apollo missions to the moon, the Viking missions to 

Mars, and the Pioneer, Voyager, Ulysses, Galileo, Cassini 

and New Horizons missions to the outer solar system all 

used radioisotope thermoelectric generators. The multimission radioisotope thermoelectric generator is a new 

generation designed to operate on planetary bodies with 

an atmosphere, such as Mars, as well as in the vacuum 

of space. In addition, it is a more flexible modular design 

capable of meeting the needs of a wider variety of missions as it generates electrical power in smaller increments, slightly over 110 watts. The design goals for the 

multi-mission radioisotope thermoelectric generator 

include ensuring a high degree of safety, optimizing 

power levels over a minimum lifetime of 14 years, and 

minimizing weight. It is about 25 inches (64 centimeters) in diameter by 26 inches (66 centimeters) long and 

weighs about 99 pounds (45 kilograms).

Like previous generations of this type of generator, the 

multi-mission radioisotope thermoelectric generator is 

built with several layers of protective material designed 

to contain its plutonium dioxide fuel in a wide range of 

potential accidents, verified through impact testing. In 

the unlikely event of a launch accident, it is unlikely that 

any plutonium would be released or that anyone would 

be exposed to nuclear material. The type of plutonium 

used in a radioisotope power system is different from 

the material used in weapons and cannot explode 

like a bomb. It is manufactured in a ceramic form that 

does not become a significant health hazard unless it 

becomes broken into very fine pieces or vaporized and 

then inhaled or swallowed. Those people who might be 

exposed in a Mars Science Laboratory launch accident 

would receive an average dose of 5 to 10 millirem, 

equal to about a week of background radiation. The average American receives 360 millirem of radiation each 

year from natural sources, such as radon and cosmic 

rays.

The electrical output from the multi-mission radioisotope thermoelectric generator charges two lithium ion 

rechargeable batteries. This enables the power subsystem to meet peak power demands of rover activities 

when the demand temporarily exceeds the generator’s 

steady output level. The batteries, each with a capacity of about 42 amp-hours, were made by Yardney 

Technical Products, Pawcatuck, Conn. They are expected to go through multiple charge-discharge cycles 

per Martian day.

Rover Telecommunication

Curiosity has three antennas for telecommunication. 

Two are for communications directly with NASA’s Deep 

Space Network antennas on Earth using a radio frequency in the X band (7 to 8 gigahertz). The third is for 

communications with Mars orbiters, using the ultra-high 

frequency (UHF) band (about 400 megahertz). 
Mars Science Laboratory Launch 44 Press Kit

X-band communications use a 15-watt, solid state 

power amplifier fed by the rover’s small deep space 

transponder, manufactured by General Dynamics 

Advanced Information Systems, Scottsdale, Ariz. Spain 

provided the rover’s high gain antenna, which is hexagonally shaped, nearly 1 foot (0.3 meter) in diameter 

and mounted near the left edge of the rover deck. With 

this antenna, the X-band subsystem is designed to 

transmit at 160 bits per second or faster to the Deep 

Space Network’s 112-foot-diameter (34-meter-diameter) antennas or at 800 bits per second or faster to the 

Deep Space Network’s 230-foot-diameter (70-meterdiameter) antennas. The high gain antenna, which 

requires pointing, can be used for either transmitting or 

receiving. The rover low-gain antenna, which does not 

require pointing, is designed primarily for receiving communications from the Deep Space Network. X-band 

reception through the high-gain antenna is anticipated 

as the typical method for daily uplink of commands to 

the rover.

The rover UHF antenna, a helix-pattern cylinder mounted high near the right-rear corner of Curiosity is fed by 

a pair of redundant Electra-Lite radios, which were built 

through a partnership between NASA’s Jet Propulsion 

Laboratory and L-3 Cincinnati Electronics, Mason, 

Ohio. These radios are software-defined, enabling them 

to autonomously adjust their data rate to suit variations 

in signal strength due to angles and transmission distance. They use standardized communication protocols 

for interoperability with all the relay orbiters at Mars, and 

are especially compatible with the adaptive Electra UHF 

radio on NASA’s Mars Reconnaissance Orbiter. The primary method for the rover’s transmission of data is anticipated to be UHF relay to the Mars Reconnaissance 

Orbiter or Mars Odyssey orbiter during two of the opportunities each Martian day when the orbiters pass in 

the sky above the rover. The European Space Agency’s 

Mars Express orbiter also has the capability to serve as 

a backup relay.

Rover Computing

Curiosity has redundant main computers, or rover 

compute elements. Of this “A” and “B” pair, it uses one 

at a time, with the spare held in cold backup. Thus, at a 

given time, the rover is operating from either its “A” side 

or its “B” side. Most rover devices can be controlled by 

either side; a few components, such as the navigation 

camera, have side-specific redundancy themselves. 

The computer inside the rover — whichever side is active — also serves as the main computer for the rest of 

the Mars Science Laboratory spacecraft during the flight 

from Earth and arrival at Mars.

Each rover compute element contains a radiation-hardened central processor with PowerPC 750 architecture: 

a BAE RAD 750. This processor operates at up to 200 

megahertz speed, compared with 20 megahertz speed 

of the single RAD6000 central processor in each of the 

Mars rovers Spirit and Opportunity. Each of Curiosity’s 

redundant computers has 2 gigabytes of flash memory 

(about eight times as much as Spirit or Opportunity), 

256 megabytes of dynamic random access memory 

and 256 kilobytes of electrically erasable programmable 

read-only memory.

The Mars Science Laboratory flight software monitors 

the status and health of the spacecraft during all phases 

of the mission, checks for the presence of commands 

to execute, performs communication functions and 

controls spacecraft activities. 

Rover Navigation

Two sets of engineering cameras on the rover — 

Navigation cameras (Navcams) up high and Hazardavoidance cameras (Hazcams) down low — will inform 

operational decisions both by Curiosity’s onboard 

autonomy software and by the rover team on Earth. 

Information from these cameras is used for autonomous 

navigation, engineers’ calculations for maneuvering the 

robotic arm and scientists’ decisions about pointing the 

remote-sensing science instruments.

Curiosity’s Navcams and Hazcams generate grayscale 

images that cover red wavelengths centered at about 

650 nanometers. The cameras themselves are virtually identical to the engineering cameras on Spirit and 

Opportunity, though Curiosity has redundant cameras 

and slightly more powerful heaters for the cameras. 

Curiosity has a total of 12 engineering cameras, each 

weighing about 9 ounces (250 grams).

Curiosity’s Navcams, paired for stereo imaging, are 

installed next to the science payload’s Mast Camera on 

the remote-sensing mast. Curiosity carries two stereo 

pairs of navigation cameras, one pair each connected 

to the rover’s two redundant computers. The navigation 

cameras that are controlled by and feed imagery to the 

“A” computer are mounted directly above the navigation cameras linked to the “B” computer. That puts the 
Mars Science Laboratory Launch 45 Press Kit

“A” pair about 6.5 feet (1.99 meters) above the ground 

when the rover is on hard, flat terrain and the cameras 

are pointed straight out (slightly lower when pointed 

downward), and the other pair 2 inches (5 centimeters) 

lower. The left and right navigation cameras in each pair 

are about 16.5 inches (42 centimeters) apart, giving 

them approximately twice as long a stereo baseline as 

the separation distance of navigation cameras on Spirit 

and Opportunity.

Each of the Navcams captures a square field of view 45 

degrees wide and tall, comparable to the field of view 

of a 37-millimeter-focal-length lens on a 35-millimeter, 

single lens reflex camera. The lens focuses the image 

onto a 1,024-pixel-by-1,024-pixel area of a chargecoupled device (CCD) detector. This yields a resolution 

of 0.82 milliradians per pixel — for example, 0.8 inch (2 

centimeters) per pixel at a distance of 82 feet (25 meters), enough to resolve a golf ball at that distance as a 

circle about two Navcam pixels wide. The depth of field 

achieved by the fixed-aperture f/12 Navcams keeps 

anything in focus from a distance of about 20 inches 

(0.5 meter) to infinity.

Curiosity has four pairs of Hazcams: two redundant 

pairs on the front of the chassis and two redundant 

pairs on the rear. The rover can drive backwards as 

well as forward, so both the front and rear Hazcams 

can be used for detecting potential obstacles in the 

rover’s driving direction. The front Hazcams also provide 

three-dimensional information for planning motions of 

the rover’s robotic arm, such as positioning of the drill or 

scoop for collecting samples. 

Each Hazcam has a fisheye lens providing a square 

field of view 124 degrees wide and tall. The depth of 

field in focus spans from about 4 inches (10 centimeters) to infinity. Resolution of the Hazcams is 2.1 milliradians per pixel on the same type of detector as in 

the Navcams. At a distance of 33 feet (10 meters), the 

Hazcam resolution is 0.8 inch (2 centimeters) per pixel. 

A golf ball at that distance would be approximately two 

Hazcam pixels across.

The redundant pairs of Hazcams are mounted side 

by side. On the front, each stereo pair has a baseline 

of 6.54 inches (16.6 centimeters) between the center 

of its left eye and center of its right eye. Both the pair 

linked to the rover’s “A” computer and the pair linked to 

the “B” computer are mounted near the bottom center 

of the front face of the chassis, about 27 inches (68 

centimeters) above ground level. The rear stereo pairs 

each have a baseline of 3.9 inches (10 centimeters), the 

same as for both the front and rear hazard-identification 

cameras on Spirit and Opportunity. The rear “A” pair 

on Curiosity is toward the port side of the rear face of 

the vehicle (on the left if a viewer were standing behind 

the rover and looking toward it). The rear “B” pair is on 

the right, or toward starboard. Both pairs are about 31 

inches (78 centimeters) above ground level.

The hazard-avoidance cameras have one-time-removable lens covers to shield them from potential dust 

raised during the rover’s landing. Pyrotechnic devices 

will remove the lens caps after landing. The navigation 

cameras gain protection from the stowed position of the 

remote-sensing mast during the landing; they do not 

have lens covers.

Different navigation modes for rover drives use images from the engineering cameras in different ways. 

Techniques include “blind” driving, hazard avoidance 

and visual odometry. The set of commands developed 

by rover planners for a single day’s drive may include a 

combination of these modes.

When using the blind-drive mode, rover planners have 

sufficient local imaging from the engineering cameras or 

Mast Camera to determine that a safe path exists, free 

of obstacles or hazards. They command the rover to 

drive a certain distance in a certain direction. In a blind 

drive, the rover’s computer calculates distance solely 

from wheel rotation; one full turn of a wheel with no slippage is nearly 25 inches (63 centimeters) of driving. It 

does not check imagery from the engineering cameras 

to assess the slippage.

When the rover planners cannot determine that a path is 

free of obstacles, they can command driving that uses 

hazard avoidance. Besides using this hazard avoidance 

in rougher terrain, they might use it for an additional segment of driving beyond a blind drive on the same day. 

Hazard avoidance requires the rover to stop frequently 

to acquire new stereo imaging in the drive direction with 

the engineering cameras and analyze the images for 

potential hazards. The rover makes decisions based on 

its analysis of the three-dimensional information provided 

by the stereo imaging. Rover planners set variables such 

as how frequently to stop and check, which cameras 

to use, and what type of decision the rover makes in 

response to a hazard detection (whether to choose a 

path around it or stop driving for the day).
Mars Science Laboratory Launch 46 Press Kit

Hazard avoidance can be supplemented with visual 

odometry. Visual odometry uses navigation camera 

images made with the cameras pointed to the side of 

the route being driven. By pausing at intervals during 

the drive to take these images, the rover can compare 

the before-and-after situation for each segment of 

the drive. It can recognize features in the images and 

calculate how far it has actually traveled during the 

intervening drive segment. Any difference between that 

distance and the distance indicated from wheel rotation is an indication that the wheels are slipping against 

the ground. In the day’s set of driving commands, rover 

planners can set the intervals at which the rover pauses 

for visual-odometry checks, as suited to the type of 

terrain being traversed. A slip limit can be set so that if 

the rover calculates that it is slipping in excess of that 

amount, it will stop driving for the day. The mode of using visual odometry checks at intervals several times the 

rover’s own length is called slip-check, to differentiate 

it from full-time visual odometry with sideways-looking 

stops as frequently as a fraction of the rover’s length.

Navigation modes differ significantly in the fraction of 

time spent with wheels in motion versus stopped for 

imaging and analysis of the images. 

Curiosity can incorporate other safety features in each 

drive, such as tilt limits. The rover’s inertial measurement unit, which incorporates gyroscopes, provides 

information about changes in tilt. This and other information about the rover’s attitude, or orientation, serve 

in use of the arm and the science instruments, and in 

pointing the high-gain antenna, as well as in navigation.

Rover Thermal

Curiosity’s thermal control system was designed to 

enable the rover to operate far from the equator so that 

the mission would have a choice of landing sites based 

on science criteria. In a range of Mars surface temperatures from minus 207 degrees Fahrenheit (minus 133 

degrees Celsius) to 81 degrees Fahrenheit (27 degrees 

Celsius), the temperature-sensitive components inside 

the rover can be maintained between minus 40 degrees Fahrenheit (minus 40 degrees Celsius) and 122 

degrees Fahrenheit (50 degrees Celsius). 

The rover’s heat rejection system has a pumpedfluid loop that can deliver heat from the multi-mission 

radioisotope thermoelectric generator when the core 

electronics need heating and take heat away from the 

core if the rover is becoming too warm. Pacific Design 

Technologies Inc., Goleta, Calif., built the pump. 

Rover size, compared with a 5-foot, 8-inch man
Mars Science Laboratory Launch 47 Press Kit

The fluid loop runs through an avionics mounting plate 

inside the insulated warm electronics box of the rover 

chassis. The multi-mission radioisotope thermoelectric 

generator cools passively with its radiator fins when its 

heat is not needed for warming the rover. For heating needs beyond the circulation of the heat rejection 

system, the rover uses electrical heaters. These enable 

flexibility in localizing and timing for the heat they provide. For example, a secondary warm electronics box 

atop the remote sensing mast uses electrical heating 

to maintain temperatures there above allowable minimums.

‘Send Your Name to Mars’ Chips

Silicon chips mounted onto Curiosity’s deck bear the 

names of people who participated in the “Send Your 

Name to Mars” program online. Each chip is about 

the size of a dime. More than 1.24 million names were 

submitted online. These names have been etched 

into silicon using an electron-beam machine used for 

fabricating microdevices at NASA’s Jet Propulsion 

Laboratory. In addition, more than 20,000 visitors to 

JPL and NASA’s Kennedy Space Center wrote their 

names on pages that have been scanned and reproduced at microscopic scale on another chip. 
Mars Science Laboratory Launch 48 Press Kit

The Mars Science Laboratory mission will place the 

rover Curiosity at the foot of a mountain of sedimentary 

strata, or layers, inside Gale Crater. The landing site at 

4.5 degrees south latitude, 137.4 degrees east longitude will give the rover access to a field site with science 

targets both on the crater floor beside the mountain and 

in the lower layers of the mountain.

Gale Crater spans 96 miles (154 kilometers) in diameter, 

giving it an area about the equivalent of Connecticut and 

Rhode Island combined. It holds a mound or mountain 

rising about 3 miles (5 kilometers) above the crater floor, 

which is higher than Mt. Rainier rises above Seattle. The 

slopes of the mountain are gentle enough for Curiosity 

to climb, though during the prime mission of one Martian 

year (98 weeks), the rover will probably not go beyond 

some particularly intriguing layers near the base.

Gale sits at a low elevation relative to most of the surface 

of Mars, suggesting that if Mars ever had much flowMars Science Laboratory Landing Site

ing water, some of it would have pooled inside Gale. 

Observations from orbit that add evidence of a wet 

history include water-related clay and sulfate minerals 

in the lower layers of the mound, and textures higher 

on the mound where it appears that mineral-saturated 

groundwater filled fractures and deposited minerals.

Stratification in the mound suggests it is the surviving 

remnant of an extensive sequence of deposits that 

were laid down after the impact that excavated the 

crater more than 3 billion years ago. A geological layer, 

called a stratum, is formed after the layer beneath it 

and before the one above it. The stack of layers that 

forms the mountain inside Gale offers a history book of 

sequential chapters recording environmental conditions 

when each stratum was deposited. This is the same 

principal of geology that makes the strata exposed in 

Arizona’s Grand Canyon a record of environmental history on Earth. For more than 150 years, geologists on 

Locations of landing sites for Curiosity and previous Mars rovers and landers
Mars Science Laboratory Launch 49 Press Kit

Earth have used stacks of strata from globally dispersed 

locations to piece together a record of Earth history. 

In Gale, the stack of layers is much taller than the stack 

admired in the Grand Canyon. It is a closer match to the 

amount of layering exposed in Mars’ Valles Marineris, 

the largest canyon in our solar system. Therefore, the 

Gale mound may offer one of the thickest continuous 

sequences of strata in the solar system. On Earth, the 

thickest sequences of strata that also contain a diversity 

of materials are the best records of Earth’s history. Like 

the most complete copy of an ancient manuscript, they 

can be used to decode and tie together less complete 

records from around the globe. It is hoped that the record at Gale will be just such a key reference for deciphering Mars’ global history. 

Gale Crater was named in 1991 for Australian astronomer Walter F. Gale (1865-1945). The mound inside 

Gale, when viewed from orbit, resembles the shape of 

Australia.

NASA’s choice of the landing site in Gale Crater in July 

2011 followed a five-year process that considered about 

60 sites and involved about 150 Mars scientists in a 

series of public workshops. Four finalist sites identified in 

2008 were mapped and examined so extensively from 

orbit that they have become four of the best-studied 

places on Mars. The detail in images taken by the High 

Resolution Imaging Science Experiment camera on 

NASA’s Mars Reconnaissance Orbiter, for example, 

reveals virtually every individual boulder big enough 

to spoil a landing. Mineral mapping by the Compact 

Reconnaissance Imaging Spectrometer on the same 

orbiter and the OMEGA spectrometer on the European 

Space Agency’s Mars Express identified mineral evidence of wet histories at all four sites. All four finalist sites 

qualified as safe for landing, so the selection could be 

made based on the sites’ scientific appeal.

The guided entry technology enabling the Mars Science 

Laboratory to land more precisely than previous Mars 

missions, coupled with Curiosity’s driving capability, 

meant that, for the first time, the main science destination for a Mars mission could be outside of the area 

that needed to qualify as safe for landing. The mission’s 

technologies for atmospheric entry, descent and landing give the spacecraft about a 99 percent probability 

of landing within an ellipse 12.4 miles (20 kilometers) by 

15.5 miles (25 kilometers). That is about one-third the 

size of the landing ellipses for Mars rovers that landed 

in 2004. Curiosity was designed and built to be able to 

drive far enough to get outside of its landing ellipse during its prime mission. 

The slopes of the mountain inside Gale Crater are too 

steep for the rover to land safely on the mountain. The 

science targets initially identified for the rover to investigate are in the lower layers of the mountain, requiring 

the rover to drive outside the landing ellipse to get to the 

science targets. Subsequent observations and analysis 

have identified additional science targets within the landing ellipse. The pace at which Curiosity gets to the features of high science interest inside and outside of the 

ellipse will depend on findings and decisions made after 

landing, including the possibility of identifying targets not 

yet known.

In Curiosity’s field site — encompassing accessible areas inside and outside of the landing ellipse — features 

that make Gale appealing to the science team include:

•	 An alluvial fan extending into the landing ellipse from 

the crater wall to the north holds material shed from 

the crater wall and likely carried by water.

•	 Down slope, southward, from the alluvial fan lies 

an exposure of hard, light-toned rock. The mineral composition of this area is unidentified so far. 

Curiosity could investigate a hypothesis that this 

exposure is sedimentary rock formed in interaction 

with water, such as salts left by the drying of a lake. 

Some relatively fresh, small craters in this part of the 

crater floor may provide access to material that has 

not experienced long exposure to the radiation environment affecting chemistry at the Martian surface.

•	 Among the exposures in the lower portion of Gale’s 

inner mountain are packages of strata that contain 

clay minerals, strata that contain sulfate salts and 

strata that contain both. Clays and sulfates both 

result from wet environments. The differences in 

mineral composition from one package of strata 

to the next can provide information about changes 

in environments that may have been favorable for 

microbial life.

•	 Curiosity’s analysis of the exposed minerals will 

provide confirmation of orbiter-based predictions for 

the distribution and abundance of similar minerals 

to be present over vast parts of Mars. In this regard, 

Curiosity will provide important ground truth of hypotheses generated by previous missions.
Mars Science Laboratory Launch 50 Press Kit

•	 The sulfate salts retain trace amounts of water in 

their mineral structure. Curiosity can monitor how 

some of that water is released into the atmosphere 

during warmer hours of the day and reabsorbed by 

the salts during colder hours. These measurements 

would provide information about the modern water 

cycle on Mars.

•	 Canyons cut into the northern flank of the mountain 

resulted from flow of water long after the lower layers of the mountain had accumulated. The canyoncutting environment could have been a separate 

habitable environment from the environment at 

the time the clay-containing and sulfate-containing 

layers formed. Analysis of material deposited at the 

mouths of the canyons could provide information 

about that later environment.

•	 Extensive networks of fractures in the upper parts 

of the sulfate-bearing strata are filled with minerals that betray circulation of groundwater. These 

fracture networks would represent yet a different, 

subsurface habitable environment. The presence 

of minerals lining these fractures indicates where 

Curiosity might conduct analyses to look for organic compounds.

One important capability of Curiosity’s science payload 

is to check for the presence of ingredients for life, including the carbon-based building blocks of biology called 

organic compounds. Long-term preservation of organic 

compounds requires special conditions. 

Clays and sulfate-rich deposits such as the ones Curiosity 

will investigate in Gale Crater can be good at latching 

onto organic chemicals and protecting them from oxidation. Another factor in long-term preservation of organics 

on Mars is protection from natural radiation that is more 

intense than what reaches Earth’s surface. Radiation may 

gradually destroy organics inside rocks at the surface, but 

Gale also offers rocks exposed by relatively recent smallcrater impacts.

Gale offers these attractive targets at which to check for 

organic compounds. Finding organics is still a long shot, 

but this chosen field site also offers records of multiple 

periods in Mars history, grist for the mission’s investigation 

of environmental changes on Mars, with strong prospects 

for identifying habitable environments. 

Should Curiosity continue to be in working condition 

following the prime mission, an extended mission could 

continue the investigation by exploring higher, younger 

layers of Gale’s mountain.

Oblique view of Curiosity’s landing area and surrounding terrain at Gale Crater, looking toward the southeast
Mars Science Laboratory Launch 51 Press Kit

Building on scientific discoveries and lessons from 

past and ongoing missions, NASA’s Mars Exploration 

Program is working to establish a sustained observational presence at Mars. This includes orbiters that view 

the planet from above and act as telecommunications 

relays, surface-based mobile laboratories, robots that 

probe below the planet’s surface, and, ultimately, missions that return soil and rock samples to Earth and 

prepare for human landing. 

With international cooperation, the long-term program is 

guided by compelling questions about Mars and developing technologies to make missions possible with 

available resources. The program’s strategy is to seek to 

uncover profound insights into Mars’ past and present 

environments, the roles and abundance of water, and 

the potential for past or present habitats suitable for the 

existence of life. 

The following are the most recently completed, ongoing 

and near-term future Mars missions of exploration by 

NASA and its international partners: 

Mars Pathfinder (December 1996 – March 1998):

The first completed mission in NASA’s Discovery 

Program of low-cost planetary missions with highly 

focused scientific goals, Mars Pathfinder set ambitious 

objectives and surpassed them. This lander released 

its Sojourner rover on the Martian surface and returned 

2.3 billion bits of information from instruments on the 

lander and the rover. The information included more 

than 17,000 images, more than 15 chemical analyses of 

rocks and soil, and extensive data on winds and other 

aspects of weather. The observations suggest that early 

Mars may have been more Earth-like with liquid water on 

its surface and a thicker atmosphere than it has today. 

The mission functioned on the Martian surface for about 

three months, well beyond the planned lifetimes of 30 

days for the lander and seven days for the rover. 

Mars Global Surveyor (November 1996 –

November 2006): During its primary mapping mission 

from March 1999 through January 2001, NASA’s Mars 

Global Surveyor collected more information than any 

previous Mars project. The orbiter continued to examine 

Mars’ surface and monitor its global weather patterns 

through three mission extensions, successfully operating longer than any previous spacecraft sent to Mars. It 

Recent, Current and Upcoming Missions

had begun a fourth extension and was five days shy of 

the 10th anniversary of its launch when it last communicated with Earth. Mars Global Surveyor returned more 

than 240,000 camera images, 206 million spectrometer 

measurements and 671 million laser-altimeter shots. 

Some of the mission’s most significant findings include: 

discovering extensive layering of the planet’s crust; 

discovering ancient deltas; discovering channels, a few 

of which exhibit modern activity suggesting modern 

liquid water; identifying concentrations of a mineral that 

often forms under wet conditions, leading to selection of 

one large deposit as the landing area for NASA’s Mars 

Exploration Rover Opportunity; laser-altimeter observations producing a nearly global map of the planet’s 

topography, quantifying altitudes and slopes, and 

characterizing myriad craters, including many eroded or 

buried craters too subtle for previous observation; compiling extensive evidence for the role of dust in reshaping 

the recent Martian environment; and detecting localized 

remnant magnetic fields, proof that Mars once had a 

global magnetic field like Earth’s, shielding the surface 

from deadly cosmic rays and slowing loss of volatiles 

to space. This orbiter provided details used to evaluate 

the risks and attractions of potential landing sites for 

the Phoenix Mars Lander and the two Mars Exploration 

Rovers. It also served as a communications relay for the 

Mars Exploration Rovers during and after their landings. 

Mars Odyssey (April 2001 – present): This NASA 

orbiter’s prime mapping mission began in March 2002. 

Its suite of gamma-ray spectrometer instruments soon 

provided strong evidence for large quantities of frozen 

water mixed into the top layer of soil in the 20 percent of 

the planet near its north and south poles. Subsequently, 

a site in this permafrost terrain became the destination for the Phoenix Mars Lander. Odyssey’s camera 

system, which examines the planet in both visible-light 

and infrared wavelengths, has identified minerals in 

rocks and soils and has compiled the highest-resolution 

global map of Mars. Nighttime infrared imaging provides 

information about how quickly or slowly surface features 

cool off after sunset, which gives an indication of where 

the surface is rocky and where it is dusty. Odyssey’s 

instruments have monitored the Mars atmosphere for 

more than a decade, including the tracking of non-condensable gases such as argon as tracers of atmospheric transport. Odyssey has also monitored high-energy 

radiation at orbital altitudes to help characterize the en-
Mars Science Laboratory Launch 52 Press Kit

vironment that future missions, including possible human 

ones, will experience. Odyssey’s observations helped 

evaluate potential landing sites for the Mars Exploration 

Rovers, Phoenix and Curiosity. Relays via this orbiter 

have been the main way for the rovers and Phoenix to 

send information to Earth; more than 95 percent of rover 

data has been returned via this communications workhorse. Odyssey is now the longest working spacecraft 

ever sent to Mars. It will continue to map the planet while 

providing relay support for Curiosity 

Mars Exploration Rover Spirit (June 2003 – March 

2010): The first of NASA’s twin Mars Exploration Rovers 

to land on Mars, Spirit was a mobile robotic field geologist sent to examine clues about the planet’s environmental history — particularly the history of water — at a 

carefully selected site. Each rover’s mission was planned 

to run for three months on Mars, but each rover worked 

for years. Spirit explored inside Gusev Crater, a highly 

eroded crater 95 miles (150 kilometers) in diameter. 

Orbital images suggested Gusev may have once held a 

lake fed by inflow from a large valley network funneling 

into the crater from highlands to the south. Spirit landed 

Jan. 4, 2004, on a flat volcanic flood-plain pocked 

with small craters and strewn with loose rocks. There, 

the rover found basaltic rocks only slightly altered by 

exposure to moisture. By June 2004, well into its first 

extended mission, Spirit had driven to a range named 

the Columbia Hills, about 1.6 miles (2.6 kilometers) from 

the landing site, in a quest to find exposed bedrock. 

Exploring in the hills, Spirit discovered a profusion of 

rocks and soils bearing evidence of extensive exposure 

to water, including the iron-oxide-hydroxide mineral 

goethite and hydrated sulfate salts. It found an outcrop 

rich in carbonate, evidence for wet conditions that were 

not acidic. Textures and compositions of materials at 

a low plateau between hills indicated an early era on 

Mars when water and hot rocks interacted in explosive 

volcanism. By driving with one immobile wheel whose 

motor had worn out after three years on Mars, Spirit 

serendipitously plowed up a hidden deposit of nearly 

pure silica. This discovery indicates that the site once 

had hot springs or steam vents, which are environments 

that, on Earth, teem with microbial life. In June 2009, 

Spirit became embedded in a patch of fine-grained 

material and was unable to extract itself after a second 

wheel stopped working. Prevented from parking itself in 

a position favorable for its solar array to generate energy, 

Spirit was apparently unable to survive the long southern 

winter, as no further communications were received.

 Mars Exploration Rover Opportunity (July 2003 

- present): This rover was sent to a flat region named 

Meridiani Planum, where the spectrometer on Mars 

Global Surveyor had discovered a large exposure of the 

mineral hematite — which often forms in the presence 

of water. On Jan. 25, 2004, Opportunity landed inside a 

crater only 72 feet (22 meters) in diameter and immediately saw exposed bedrock in the crater’s inner slope. 

During the next few weeks, the rover’s examination 

of that outcrop settled the long-running debate about 

whether Mars ever had sustained liquid water on its surface. Composition and textures showed that the rocks 

not only had been saturated with water, but had actually 

been laid down under gently flowing surface water. 

For six months beginning in June 2004, Opportunity 

examined deeper layers of rock inside a stadium-size 

crater, Endurance, about half a mile (700 meters) from 

the landing site. The wall-rock layers had all soaked in 

water, but textures in some showed that periods of dry, 

wind-blown deposition alternated with periods when 

water covered the surface. After examining its own jettisoned heat shield and a nickel-iron meteorite near this 

crater, Opportunity drove more than 4 miles (6 kilometers) southward to reach an even larger and deeper 

crater, Victoria. Here, it examined geological evidence 

of similar environmental conditions from a greater span 

of time. The presence of sulfur-rich material throughout 

Opportunity’s study area indicates acidic watery environments. In mid-2008, Opportunity set off toward a 

crater 14 miles (22 kilometers) in diameter, Endeavour, 

where orbital observations have detected water-related 

clay minerals, different from any Opportunity has seen 

so far and indicative of less-acidic watery environments. 

In August 2011, with a total driving odometry of more 

than 21 miles (34 kilometers), the rover reached the rim 

of Endeavour Crater to start a new phase of its exploration of Mars, demonstrating once more the value of 

mobility and longevity.

Mars Express (June 2003 – present): This is a 

European Space Agency orbiter with NASA participation in two of its seven investigations: a ground-penetrating radar, and a tool for studying how the solar wind 

removes water vapor from Mars’ outer atmosphere. 

The spacecraft has been returning color stereo images 

and other data since January 2004 after entering orbit 

in late December 2003. Its spectrometer for visible 

and near-infrared wavelengths found deposits of clay 

minerals indicating a long-ago wet environment that 

was less acidic than the one that produced the minerals studied by Opportunity. Scientists working with this 

and similar data from the Mars Reconnaissance Orbiter 
Mars Science Laboratory Launch 53 Press Kit

have proposed a sequence of globally distributed water 

environments very early in Mars’ history, moving from 

less to more acidic environments. Meanwhile, scientists 

working with data from a thermal infrared spectrometer 

found indications of methane in Mars’ atmosphere by 

averaging millions of spectra to improve signal-to-noise 

ratio. Scientists presently believe that this gas would 

break down too rapidly to be detectable unless there 

is an active source, either biological or non-biological, 

maintaining its concentration in the atmosphere. These 

discoveries have important implications for the habitability of Mars, past and present. Since deployment of the 

radar antenna in June 2005, the spacecraft has examined ice-rich layered deposits covering the polar regions. 

Mars Reconnaissance Orbiter (August 2005 – 

present): This multipurpose spacecraft is examining the 

surface, subsurface and atmosphere of Mars in unprecedented detail. It began its primary science investigations 

in November 2006, following 426 carefully planned dips 

into the top of Mars’ atmosphere to adjust the size and 

shape of its orbit after arriving at Mars in March 2006. 

Specifically engineered to return the vast volumes of data 

generated by the high spatial resolution of its imaging 

cameras and spectrometer, the orbiter has returned 

more than three times as much data as the combined 

total from all other space missions that have traveled 

farther than the moon. NASA’s Deep Space Network 

antennas received more than 130 terabytes of data — 

including more than 70,000 images — from the six science instruments on Mars Reconnaissance Orbiter during the mission’s first five years at Mars. The mission has 

illuminated three very different periods of Mars’ history. Its 

observations show that different types of watery environments formed extensive deposits of water-related minerals — including clays, sulfates and carbonates — across 

the planet early in Mars’ history. In more recent times, 

water appears to have cycled as a gas between polar 

ice deposits and lower-latitude deposits of ice and snow. 

Radar observations reveal internal, episodic patterns of 

layering probably connected to cyclical variations in the 

tilt of the planet’s rotation axis and the elliptical nature of 

its orbit. These cycles modulate the solar heating of the 

poles to a much larger degree than occurs for Earth, 

with its ice ages, over periods of thousands to a few 

million years. Radar has also revealed a thick deposit of 

carbon-dioxide ice buried in the south polar cap, which, 

if released into the atmosphere, would nearly double 

the amount of gas in the atmosphere today. With observations of new craters, avalanches and dust storms 

occurring even now, the orbiter has shown that modern 

Mars is still a dynamic world. The orbiter’s observations 

have identified sites with high potential for future scientific discovery. In addition, the orbiter’s high-resolution 

cameras can reveal hazards to landing and roving 

spacecraft, such as rocks and steep slopes, while its 

atmospheric monitors characterize the environment that 

can be encountered during landing and operations on 

the surface. Observations by the Mars Reconnaissance 

Orbiter enabled the Phoenix mission to choose a landing site less rocky than one previously considered. The 

orbiter has examined potential landing sites for Mars 

Science Laboratory and will serve as a relay asset during 

the landing and surface operations of Curiosity. 

Phoenix Mars Lander (August 2007 – November 

2008): In 2001, NASA announced a new program of 

competitively proposed and selected missions to Mars: 

Mars Scout missions. The Phoenix Mars Lander proposal, submitted by a team led by Peter Smith of the 

University of Arizona, Tucson, was selected out of 25 

proposals in 2003 to be the one developed for launch in 

2007. The mission sent a stationary lander with a robotic 

digging arm and suite of science instruments to study 

the summer environment in a far-northern zone. Phoenix 

confirmed and examined deposits of underground water 

ice detected from orbit by Mars Odyssey. It identified a 

mineral called calcium carbonate that suggested occasional presence of thawed water. The lander also found 

soil chemistry with significant implications for life and observed falling snow. The mission’s biggest surprise was 

the discovery of perchlorate, an oxidizing chemical on 

Earth that is food for some microbes and potentially toxic 

for others, and which can lower the freezing point of 

liquid water by tens of degrees. It completed its planned 

three months of operation on Mars and worked two 

extra months before the anticipated seasonal decline in 

solar energy at its high latitude ended the mission. 

Mars Atmosphere and Volatile Evolution 

Mission, or MAVEN (for launch in 2013): The second Mars Scout mission, selected from 26 competitive 

proposals in 2007, will explore the planet’s upper atmosphere, ionosphere and interactions with the sun and 

solar wind. Various evidence suggests that Mars was a 

wetter planet early in its history. Where has that water 

gone? Scientists will use MAVEN data to determine the 

role that loss of volatile compounds, such as carbon 

dioxide and water, from the Mars atmosphere to space 

has played through time, giving insight into the history 

of Mars’ atmosphere and climate, liquid water, and 

planetary habitability. The principal investigator is Bruce 

Jakosky, University of Colorado, Boulder.
Mars Science Laboratory Launch 54 Press Kit

ExoMars Trace Gas Orbiter (for launch in 2016): 

NASA and the European Space Agency (ESA) have embarked on a joint program to explore Mars. The ExoMars 

Trace Gas Orbiter will be the first in a series of planned 

joint robotic missions. It will study the chemical makeup 

of the Martian atmosphere with a 1,000-fold increase in 

sensitivity over previous Mars orbiters. The mission will 

focus on trace gases, including methane, which could 

be potentially geochemical or biological in origin and be 

indicators for the existence of life on Mars today. The 

mission also will serve as an additional communications relay for Mars surface missions beginning in 2018. 

NASA and ESA selected five science investigations for 

ExoMars Trace Gas Orbiter in 2010. The mission will also 

carry a European-built small lander demonstrator. 

InSight (in consideration for launch in 2016): One 

of three competing proposals selected as finalists for 

a 2016 launch as part of NASA’s Discovery Program 

would study Mars. If chosen to fly, the proposed mission would investigate the structure and composition of 

the interior of Mars and advance understanding of the 

formation and evolution of rocky planets. It would carry 

a seismometer and a subsurface thermal probe, and it 

would use radio tracking of tiny variations in Mars’ motions to provide information about the planet’s core. The 

principal investigator is Bruce Banerdt at JPL.

Beyond 2016: NASA is collaborating with the 

European Space Agency to gain further understanding 

of Mars, including whether Mars has supported life. This 

international partnership is in the early stages of creating a joint rover mission that would access and analyze 

subsurface materials, and characterize and prepare 

samples for possible analysis by Earth-based laboratories. Concepts for a program to return samples from 

Mars to Earth envision a campaign of multiple missions 

performing different steps in that challenge.
Mars Science Laboratory Launch 55 Press Kit

Mars Science: A Story of Changes

As the world in 1965 eagerly awaited results of the first 

spacecraft flyby of Mars, everything we knew about the 

Red Planet was based on what sparse details could be 

gleaned by peering at it from telescopes on Earth. Since 

the early 1900s, popular culture had been enlivened by 

the notion of a habitable neighboring world crisscrossed 

by canals and, possibly, inhabited by advanced life 

forms that might have built them — whether friendly or 

not. Astronomers were highly skeptical about the canals, which looked more dubious the closer they looked. 

About the only hard information they had on Mars was 

that they could see it had seasons with ice caps that 

waxed and waned, along with seasonally changing 

surface markings. By breaking down the light from Mars 

into colors, they learned that its atmosphere was thin 

and dominated by an unbreathable gas, carbon dioxide.

The past four decades have revolutionized that view. 

First, hopes of a lush, Earth-like world were deflated 

when Mariner 4’s flyby on July 15, 1965, revealed large 

impact craters, like craters that cover Earth’s barren, lifeless moon. Those holding out for Martians were further 

discouraged when NASA’s two Viking landers were sent 

to the surface in 1976 equipped with a suite of chemistry experiments that turned up no conclusive sign of 

biological activity. Mars as we came to know it was cold, 

nearly airless and bombarded by hostile radiation from 

both the sun and from deep space.

Since then, however, new possibilities of a more hospitable Martian past have emerged. Mars is a much more 

complex body than Earth’s moon. Scientists scrutinizing 

pictures from the orbiters of the 1970s detected surface 

features potentially shaped by liquid water, perhaps 

even the shoreline of an ancient ocean. Eight successful 

Mars missions since the mid-1990s have advanced the 

story. Accumulated evidence shows that the surface of 

Mars appears to be shaped by flowing water in hundreds of places; that some Mars rocks formed in water; 

that significant amounts of water as ice and in hydrated 

minerals still make up a fraction of the top surface layer 

of Mars in many areas; and that water may, even today, 

occasionally emerge from the ground to flow briefly 

before freezing or evaporating. 

Although it appears unlikely that complex organisms 

similar to advanced life on Earth could have existed 

on Mars’ comparatively hostile surface, scientists are 

intrigued by the possibility that life in some form — 

perhaps very simple microbes — may have gained a 

foothold in ancient times when Mars was wetter, if not 

warmer. It is not unthinkable that life in some form could 

persist today in underground springs warmed by heat 

vents around smoldering volcanoes, or even beneath 

the thick ice caps. To investigate those possibilities, 

NASA’s productive strategy has been to learn more 

about the history of water on Mars: How much was 

there? How long did it last? Where are formerly wet environments that make the best destinations for seeking 

evidence of past life? Where might there be wet environments capable of sustaining life today? 

The consensus strategy for answering those questions 

uses a balance of examining selected sites in great 

detail while also conducting planet-wide surveys to 

provide context for interpreting the selected sites. This 

enables researchers to extrapolate from the intensively 

investigated sites to regional and global patterns, and to 

identify which specific sites make the best candidates 

for targeted examination.

One way this balance works is in the combination 

punch of orbital and surface missions. Mineral mapping by NASA’s orbiting Mars Global Surveyor identified 

a hematite deposit that made Meridiani Planum the 

selected landing site for NASA’s Mars Exploration Rover 

Opportunity. The hematite suggested a possible water 

history. Opportunity’s examination of the composition 

and fine structure of rocks where it landed confirmed 

that the site had had surface and underground water, 

and added details about the acidity of the water and the 

alternation of wet and dry periods at the site. Meanwhile, 

halfway around the planet at Gusev Crater, the Spirit 

rover found evidence of materials altered in an ancient 

hydrothermal system. This “ground truthing” by the rover 

improves interpretation of current orbiters’ observations 

of the surrounding region. Conversely, orbiters’ observations add context for understanding how the environment that landing-site rocks reveal about a particular 

place and time fits into a broader history. 

Similarly, the Phoenix Mars Lander investigated a site 

with intriguing characteristics discovered from orbit. 

Spectrometers on NASA’s Mars Odyssey orbiter found 

evidence of copious water ice within the top 3 feet (1 

meter) of the surface in high-latitude and some mid-
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latitude regions. Phoenix landed at a far-northern site 

and confirmed the presence of plentiful water ice just 

beneath the surface. In the soil above the ice, Phoenix 

found a chemical called perchlorate, which could serve 

as an energy source for microbes and as a potent antifreeze enabling water to be liquid at low temperature. 

As another example of the synergy among Mars spacecraft, NASA’s Mars Reconnaissance Orbiter, which 

reached Mars in 2006, found a less rocky, safer landing site for Phoenix. The orbiter also examined more 

than 30 potential landing sites for the Mars Science 

Laboratory. Four finalist sites were examined in thorough detail to identify specific mineral deposits of interest and potential landing hazards down to the scale of 

individual rocks before Gale Crater was chosen as the 

landing site.

The Mars Science Laboratory is NASA’s first astrobiology mission to Mars since the Viking landers. One goal 

of NASA’s Astrobiology Program is to determine the 

history of any environment having liquid water, other 

chemical ingredients of life, and energy sources that 

might have sustained living systems. Astrobiology’s 

investment in Mars exploration is geared toward identifying, categorizing and understanding locations on 

Mars that may have once supported habitable environments. This includes developing tools and techniques 

for identifying mineralogical and physical signs of liquid 

water, biosignatures and chemical evidence of ancient 

habitats.

Myths and Reality

Mars caught public fancy in the late 1870s, when Italian 

astronomer Giovanni Schiaparelli reported using a telescope to observe “canali,” or channels, on Mars. A possible mistranslation of this word as “canals” may have 

fired the imagination of Percival Lowell, an American 

businessman with an interest in astronomy. Lowell 

founded an observatory in Arizona, where his observations of Mars convinced him that the canals were dug 

by intelligent beings — a view that he energetically 

promoted for many years. 

By the turn of the last century, popular songs envisioned sending messages between worlds by way of 

huge signal mirrors. On the dark side, H.G. Wells’ 1898 

novel “The War of the Worlds” portrayed an invasion of 

Earth by technologically superior Martians desperate for 

water. In the early 1900s novelist Edgar Rice Burroughs, 

known for the “Tarzan” series, also entertained young 

readers with tales of adventures among the exotic 

inhabitants of Mars, which he called Barsoom.

Fact began to turn against such imaginings when the 

first robotic spacecraft were sent to Mars in the 1960s. 

Pictures from the 1965 flyby of Mariner 4 and the 1969 

flybys of Mariner 6 and 7 showed a desolate world, 

pocked with impact craters similar to those seen on 

Earth’s moon. Mariner 9 arrived in 1971 to orbit Mars 

for the first time, but showed up just after an enormous 

dust storm had engulfed the entire planet. When the 

storm died down, Mariner 9 revealed a world that, 

while partly crater-pocked like Earth’s moon, was much 

more geologically complex, complete with gigantic 

canyons, volcanoes, dune fields and polar ice caps. 

This first wave of Mars exploration culminated in the 

Viking mission, which sent two orbiters and two landers to the planet in 1975. The landers carried a suite of 

experiments that conducted chemical tests to detect 

life. Most scientists interpreted the results of these tests 

as negative, deflating hopes of identifying another world 

where life might be or have been widespread. However, 

Viking left a huge legacy of information about Mars that 

fed a hungry science community for two decades. 

The science community had many other reasons for 

being interested in Mars, apart from the direct search 

for life. The next mission on the drawing boards concentrated on a study of the planet’s geology and climate 

using advanced orbital reconnaissance. Over the next 

20 years, however, new findings in laboratories and in 

extreme environments on Earth came to change the 

way that scientists thought about life and Mars.

One was the 1996 announcement by a team from 

Stanford University and NASA’s Johnson Space Center 

that a meteorite believed to have originated on Mars 

contained what might be the fossils of ancient bacteria. 

This rock and other Mars meteorites discovered on several continents on Earth appear to have been blasted 

off Mars by asteroid or comet impacts. The evidence 

that they are from Mars comes from gases trapped in 

them that unmistakably match the composition of Mars’ 

atmosphere as measured by the Viking landers. Many 

scientists have questioned the conclusions of the team 

announcing the discovery of possible life in one Martian 

meteorite, but if nothing else, the mere presence of 

organic compounds in the meteorites increases the 

odds of life forming at an earlier time on a wetter Mars. 

The debate has also focused attention on what types 

of experiments would be most useful for assessing 
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whether an extraterrestrial site or sample has ever held 

anything alive.

Another development shaping ideas about extraterrestrial life was a string of spectacular findings on how 

and where life thrives on Earth. The fundamental requirements for life as we know it today are liquid water, 

organic compounds and an energy source for synthesizing complex organic molecules. In recent years, it has 

become increasingly clear that life can thrive in settings 

much harsher than what we as humans can experience.

In the 1980s and 1990s, biologists found that microbial 

life has an amazing flexibility for surviving in extreme 

environments — niches that by turn are extraordinarily 

hot, or cold, or dry, or under immense pressures — that 

would be completely inhospitable to humans or complex animals. Some scientists even deduce that life on 

Earth may have begun at hot vents far under the ocean’s 

surface.

This in turn had its effect on how scientists thought 

about Mars. Martian life might not be so widespread that 

it would be readily found at the foot of a lander spacecraft, but it may have thrived billions of years ago in an 

underground thermal spring or other hospitable environment. Or it might still exist in some form in niches below 

the currently frigid, dry, windswept surface, perhaps 

shielded in ice or in liquid water aquifers.

Each successful Mars mission uncovers more pages of 

the planet’s story. After years of studying pictures from 

the Mariner 9 and Viking orbiters, scientists gradually 

came to conclude that many features they saw suggested that Mars may have been warm and wet in an 

earlier era. 

Two decades after Viking, NASA’s Mars Pathfinder 

observed rounded pebbles and sockets in larger rocks, 

suggesting conglomerates that formed in running water. 

Mars Global Surveyor’s camera detected possible evidence for recent liquid water in many settings, including 

hundreds of hillside gullies. That orbiter’s longevity even 

allowed before-and-after imaging that showed fresh 

gully-flow deposits in 2005 that had not been present 

earlier in the mission. Observations by Global Surveyor 

and Odyssey have also been interpreted as evidence 

that Mars is still adjusting from a recent ice age as part of 

a repeating cycle of global climate change. The cycle results from changes in the tilt of the rotational axis of Mars 

on time scales of hundreds of thousands to a few million 

years. Mars’ tilt varies much more than Earth’s.

NASA’s Mars Exploration Rover Opportunity established 

that rocks in at least one part of Mars were formed under flowing surface water billions of years ago. Minerals 

present indicate the ancient water was very acidic. 

Halfway around the planet, Opportunity’s twin, Spirit, 

found a carbonate deposit offering evidence for a wet 

environment that was less acidic and found a nearly 

pure silica deposit formed by a hot spring or steam vent. 

Either of those long-ago environments deduced from 

Spirit’s observations could have been even more favorable for microbial life than the conditions that left the 

clues found by Opportunity. 

The European Space Agency’s Mars Express has identified exposures of clay minerals that probably formed 

in long-lasting, less-acidic wet conditions even earlier 

in Mars history than the conditions that produced the 

minerals examined by Opportunity through 2010. Mars 

Express and telescopic studies from Earth have found 

traces of atmospheric methane at Mars that might come 

from volcanic or biological sources. A radar instrument 

co-sponsored by NASA and the Italian Space Agency 

on the European orbiter has assessed the thickness and 

water content of icy layers covering Mars’ south polar 

region, yielding an estimate that the quantity of water frozen into those icy layers is equivalent to a 36-foot-thick 

(11-meter-thick) coating of the whole planet.

Since 2006, NASA’s Mars Reconnaissance Orbiter has 

radically expanded our knowledge of the Red Planet. 

Observing the planet at the highest spatial resolutions 

yet achieved from orbit, this mission has provided copious information about ancient environments, ice-agescale climate cycles and present-day changes on Mars. 

It has mapped water-related mineral deposits, including 

multiple types of clay minerals, in hundreds of locations, 

and carbonates in several locales, confirming a story of 

alteration by water in a diversity of environments early in 

Martian history and a dramatic change to very acidic water in many areas after an era of more neutral conditions. 

With regard to recent Mars history, the Mars 

Reconnaissance Orbiter has added evidence of ongoing 

climate-change cycles linked to how changes in the tilt 

of the planet’s rotation axis alter intensity of sunlight near 

the poles. This evidence includes radar observations of 

episodic layering within the polar ice caps and of debriscovered ice deposits. Other observations have revealed 

water ice just below the surface in middle latitudes, 

exposed in small craters formed by fresh impacts identified in before-and-after observations. These findings and 

their implications for ongoing cycles of climate change 
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put water ice closer to the equator on modern Mars, including possibly beneath the Viking 2 Lander, than most 

researchers imagined a few years ago. 

Orbital studies in recent years have also revealed some 

processes on Mars very unlike those on Earth related to 

temperatures low enough to freeze some of the carbondioxide gas out of the planet’s thin atmosphere, which is 

mostly that gas. Carbon-dioxide ice blankets the ground 

around whichever pole is in winter. In the spring, sunlight 

penetrates the translucent ice, heating it from below. 

As the carbon dioxide thaws back into gas, it triggers 

geyser-like eruptions in some areas and fresh flows of 

sand on slopes in other areas. 

The surface pressure of the Mars atmosphere varies 

over the year as the seasonal carbon-dioxide frost forms 

and then sublimes at each pole in turn. A major finding 

by the radar on Mars Reconnaissance Orbiter is a thick, 

hidden layer of carbon-dioxide ice deep in the water 

ice that forms the bulk of the south polar ice cap. This 

deposit may contain nearly as much carbon-dioxide as 

today’s Martian atmosphere. This implies that the total 

mass of the atmosphere on Mars can change several 

fold on time scales of hundreds of thousands of years 

or less. Computer modeling indicates that during larger 

tilt, when summertime solar heating at the poles is more 

intense, most of the frozen carbon-dioxide rejoins the 

atmosphere, and that during smaller tilt, most of the 

atmosphere freezes out. 

Modern Mars is a more dynamic planet today than we 

realized before the advent of frequent, high-resolution 

imaging. Hundreds of sets of before-and-after images 

from Mars Global Surveyor and Mars Reconnaissance 

Orbiter document soil flowing down gullies, rocks 

bouncing down hills, dunes migrating, craters forming, 

icy layers receding and dust blowing. Cameras in orbit 

have even caught avalanches and tall whirlwinds as they 

happen. Image sequences from Spirit show the motions 

of dust devils dancing across the landscape and clouds 

scooting across the sky. Thus, the Martian landscape, 

which has changed dramatically in the past, continues 

to change today.

Three Ages of Mars

Based on what they have learned from spacecraft missions, scientists view Mars as the “in-between” planet 

of the inner solar system. Small rocky planetary bodies 

such as Mercury and Earth’s moon apparently did not 

have enough internal heat to drive the motion of tectonic 

plates, so their crusts grew cold and static relatively 

soon after they formed when the solar system condensed into planets about 4.6 billion years ago. Devoid 

of atmospheres, they are riddled with craters that are relics of impacts from a period of bombardment when the 

inner planets were sweeping up remnants of small rocky 

bodies that failed to “make it as planets” in the solar 

system’s early times.

Earth and Venus, by contrast, are larger planets with 

substantial internal heat sources and significant atmospheres. Earth’s surface is continually reshaped by 

tectonic plates sliding under and against each other and 

by materials spouting forth from active volcanoes where 

plates are ripped apart. Both Earth and Venus have 

been paved over so recently that both lack any discernible record of cratering from the era of bombardment in 

the early solar system.

On the basis of current yet evolving knowledge, Mars 

appears to stand between those sets of worlds. Like 

Earth and Venus, it possesses many volcanoes, although they probably did not remain active as long as 

counterparts on Earth and Venus. On Earth, a single 

“hot spot” or plume might form a chain of middling-size 

islands, such as the Hawaiian Islands, as a tectonic 

plate slowly slides over it. On Mars, there are apparently no such tectonic plates, at least as far as we know 

today, so when volcanoes formed in place they had the 

time to become much more enormous than the rapidly 

moving volcanoes on Earth. Overall, Mars appears to be 

neither as dead as Mercury and our moon, nor as active 

as Earth and Venus. As one scientist quips, “Mars is a 

warm corpse, if not a fire-breathing dragon.” Thanks to 

the ongoing observations by current missions, however, 

this view of Mars is still evolving.

Mars almost resembles two different worlds that have 

been glued together. From latitudes around the equator to the south are ancient highlands pockmarked with 

craters from the solar system’s early era, yet riddled with 

channels that attest to the flow of water. The northern 

third of the planet, however, overall is sunken and much 

smoother at mile (kilometer) scales. Analysis of subsurface densities by their gravitational effect on orbiters 

supports a theory that an impactor almost big enough 

to be a planet itself bashed Mars early in Martian history, 

excavating the largest crater in the solar system. If that 

happened, it was long-enough ago that it would not 

explain the smoothness of the northern plains. Theories 

for that range from proposing that the plains are the floor 
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of an ancient sea to proposing that the smoothness is 

merely the end product of innumerable lava flows.

Scientists today view Mars as having had three broad 

ages, each named for a geographic area that typifies it:

• The Noachian Era is the name given to the time 

spanning roughly the first billion years of Mars’ existence 

after the planet was formed 4.6 billion years ago. In this 

era, scientists suspect that Mars was quite active with 

periods of warm and wet environments, erupting volcanoes and some degree of tectonic activity. The planet 

may have had a thicker atmosphere to support flowing 

water, and it may have rained and snowed.

• In the Hesperian Era, which lasted for about the 

next 500 million to 1.5 billion years, geologic activity was 

slowing down and near-surface water perhaps was 

freezing to form surface and buried ice masses. Despite 

plunging temperatures, water pooled underground 

erupted when heated by impacts in catastrophic 

floods that surged across vast stretches of the surface 

— floods so powerful that they unleashed the force 

of thousands of Mississippi Rivers. Eventually, water 

became locked up as permafrost or subsurface ice, or 

was partially lost into outer space.

• The Amazonian Era is the current age that began 

around 2 billion to 3 billion years ago. The planet is 

now a dry, desiccating environment with only a modest 

atmosphere in relation to Earth. In fact, the atmosphere 

is so thin that pure water exposed to it can be stable 

only as a solid or a gas, not as a liquid. The climate and 

perhaps the stability of water at the surface may vary on 

scales of thousands to millions of years as the tilt of the 

planet and its distance from the sun waver cyclically.

Apart from that broad outline, there is lively debate and 

disagreement on the details of Mars’ history. How wet 

was the planet, and how long ago? What eventually 

happened to all of the water? That is all a story that is 

still being written.

Even if we ultimately learn that Mars never harbored life 

as we know it here on Earth, scientific exploration of the 

Red Planet can assist in understanding the history and 

evolution of life on our own world. Much if not all of the 

evidence for the origin of life here on Earth has been 

obliterated by the rapid pace of weathering and global 

tectonics that have operated over billions of years. Mars, 

by comparison, is a composite world with some regions 

that may have histories similar to Earth’s ancient crust, 

while others are a frozen gallery of the solar system’s 

early days. 

Thus, even if life never developed on Mars — something 

that we cannot answer just yet —scientific exploration of 

the planet may yield critical information unobtainable by 

any other means about the pre-biotic chemistry that led 

to life on Earth. Mars as a fossil graveyard of the chemical conditions that fostered life on Earth is an intriguing 

possibility.
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Mission: Country, Launch Date, Purpose, Results

Marsnik 1: USSR, 10/10/60, Mars flyby, did not reach 

Earth orbit

Marsnik 2: USSR, 10/14/60, Mars flyby, did not reach 

Earth orbit

Sputnik 22: USSR, 10/24/62, Mars flyby, achieved 

Earth orbit only

Mars 1: USSR, 11/1/62, Mars flyby, radio failed at 65.9 

million miles (106 million kilometers)

Sputnik 24: USSR, 11/4/62, Mars flyby, achieved Earth 

orbit only

Mariner 3: U.S., 11/5/64, Mars flyby, shroud failed to 

jettison

Mariner 4: U.S. 11/28/64, first successful Mars flyby 

7/14/65, returned 21 photos

Zond 2: USSR, 11/30/64, Mars flyby, passed Mars but 

radio failed, returned no planetary data

Mariner 6: U.S., 2/24/69, Mars flyby 7/31/69, returned 

75 photos

Mariner 7: U.S., 3/27/69, Mars flyby 8/5/69, returned 

126 photos

Mars 1969A: USSR, 3/27/69, Mars orbiter, did not 

reach Earth orbit

Mars 1969B: USSR, 4/2/69, Mars orbiter, failed during 

launch

Mariner 8: U.S., 5/8/71, Mars orbiter, failed during 

launch

Kosmos 419: USSR, 5/10/71, Mars lander, achieved 

Earth orbit only

Mars 2: USSR, 5/19/71, Mars orbiter/lander arrived 

11/27/71, no useful data, lander burned up due to steep 

entry

Historical Mars Missions 

Mars 3: USSR, 5/28/71, Mars orbiter/lander, arrived 

12/3/71, lander operated on surface for 20 seconds 

before failing

Mariner 9: U.S., 5/30/71, Mars orbiter, operated in orbit 

11/13/71 to 10/27/72, returned 7,329 photos

Mars 4: USSR, 7/21/73, failed Mars orbiter, flew past 

Mars 2/10/74

Mars 5: USSR, 7/25/73, Mars orbiter, arrived 2/12/74, 

lasted a few days

Mars 6: USSR, 8/5/73, Mars flyby module and lander, 

arrived 3/12/74, lander failed due to fast impact

Mars 7: USSR, 8/9/73, Mars flyby module and lander, 

arrived 3/9/74, lander missed the planet

Viking 1: U.S., 8/20/75, Mars orbiter/lander, orbit 

6/19/76-1980, lander 7/20/76-1982

Viking 2: U.S., 9/9/75, Mars orbiter/lander, orbit 8/7/76-

1987, lander 9/3/76-1980; combined, the Viking orbiters and landers returned more than 50,000 photos

Phobos 1: USSR, 7/7/88, Mars orbiter and Phobos 

lander, lost 8/88 en route to Mars

Phobos 2: USSR, 7/12/88, Mars orbiter and Phobos 

lander, lost 3/89 near Phobos

Mars Observer: U.S., 9/25/92, Mars orbiter, lost just 

before Mars arrival 8/21/93

Mars Global Surveyor: U.S., 11/7/96, Mars orbiter, 

arrived 9/12/97, high-detail mapping through 1/00, third 

extended mission completed 9/06, last communication 

11/2/06 

Mars 96: Russia, 1/16/96, orbiter/two landers/two penetrators, launch vehicle failed

Mars Pathfinder: U.S., 12/4/96, Mars lander/rover, 

landed 7/4/97, completed prime mission and began 

extended mission 8/3/97, last transmission 9/27/97
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Nozomi: Japan, 7/4/98, Mars orbiter, failed to enter 

orbit 12/03 

Mars Climate Orbiter: U.S., 12/11/98, lost upon arrival 9/23/99

Mars Polar Lander/Deep Space 2: U.S., 1/3/99, 

lander/two penetrators, lost on arrival 12/3/99

Mars Odyssey: U.S., 3/7/01, Mars orbiter, arrived 

10/24/01, completed prime mission 8/25/04, currently 

conducting extended mission of science and communication relay

Mars Express/Beagle 2: European Space Agency, 

6/2/03, Mars orbiter/lander, orbiter completed prime 

mission 11/05, currently in extended mission; lander 

lost on arrival 12/25/03

Mars Exploration Rover Spirit: U.S., 6/10/03, Mars 

rover, landed 1/4/04 for three-month prime mission 

inside Gusev Crater, completed several extended missions, last communication 3/22/10

Mars Exploration Rover Opportunity: U.S., 7/7/03, 

Mars rover, landed 1/25/04 for three-month prime mission in Meridiani Planum region, currently conducting 

extended mission

Mars Reconnaissance Orbiter: U.S., 8/12/05, Mars 

orbiter, arrived 3/12/06, completed prime mission 

9/26/10, currently conducting extended mission of science and communication relay

Phoenix Mars Lander: U.S., 8/4/07, Mars lander, 

landed 5/25/08, completed prime mission and began 

extended mission 8/26/08, last communication 11/2/08
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The Mars Science Laboratory Project is managed by 

the Jet Propulsion Laboratory, Pasadena, Calif., for 

NASA’s Science Mission Directorate, Washington. JPL 

is a division of the California Institute of Technology in 

Pasadena.

At NASA Headquarters, Washington, the Mars 

Exploration Program is managed by the Science 

Mission Directorate. Edward Weiler is associate administrator for the Science Mission Directorate and 

Charles Gay is deputy associate administrator. Douglas 

McCuistion is director of the Mars Exploration Program. 

Program Project Management 

Michael Meyer is lead scientist for the Mars Exploration 

Program and program scientist for the Mars Science 

Laboratory. Mary Voytek is deputy program scientist for 

the Mars Science Laboratory. David Lavery is program 

executive for the Mars Science Laboratory.

At JPL, Fuk Li is Mars Program manager and Roger 

Gibbs is deputy manager. Richard Zurek and David 

Beaty are Mars chief scientists. Peter Theisinger is Mars 

Science Laboratory project manager and Richard Cook 

is deputy project manager. John Grotzinger, of Caltech, is 

Mars Science Laboratory project scientist, and Joy Crisp 

and Ashwin Vasavada are deputy project scientists.
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