PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

Contact: Diane Ainsworth

FOR IMMEDIATE RELEASE                   January 31, 1996

MARS PATHFINDER LANDER AND ROVER FULLY INTEGRATED 

     Heading into the home stretch of spacecraft assembly, NASA's 
Mars Pathfinder lander -- a tetrahedral-shaped spacecraft 
weighing 351 kilograms (772 pounds) and standing about 1 meter 
(3.2 feet) tall -- was mated today with its companion rover, 
Sojourner, just as it will fly to Mars later this year.  

     The lander and rover, in development at NASA's Jet 
Propulsion Laboratory, crossed a major engineering milestone with 
full integration after a year of rigorous testing of components 
making up the spacecraft's landing gear, said Brian Muirhead, 
Pathfinder flight system manager. Subsystems included a 
parachute, measuring 12.7 meters (41 feet) in diameter, three 
small, rocket-assisted deceleration thrusters to help the 
spacecraft brake through the Martian atmosphere, and giant, 
multi-lobed air bags to cushion its landing.   
    
     Now with its rover mounted and secured by cables to an 
inside petal, Pathfinder will be folded up to undergo integration 
testing in the next several days, Muirhead said.  In the weeks 
ahead, the spacecraft will next be attached to the inside of its 
backshell and then be encased in a Viking-derived heatshield.  

     "This is actually the first and last time that we will see 
Pathfinder and Sojourner completely assembled until just before 
launch," Muirhead said. "It's exciting to see the spacecraft in 
full flight configuration, and to know that we have set a new 
standard for JPL and the world in the development of 
interplanetary spacecraft."

     Currently residing in JPL's spacecraft assembly clean room, 
Pathfinder will be delivered to JPL's 25-foot space simulator in 
March for spin-balance, acoustic and thermal vacuum testing, 
added Robert Manning, flight system chief engineer. Over the 
summer, the spacecraft will be taken apart again for final pyro 
and electrical testing before its components are prepared for 
shipping on Sept. 1 to Cape Canaveral, Fla.

     Pathfinder is designed to place a low-cost delivery system 
on the surface of Mars, demonstrating a new and unconventional 
atmospheric entry and landing approach. The spacecraft will be 
launched on Dec. 2 from Cape Canaveral, Fla., and spend seven 
months cruising to Mars. Landing on an ancient flood basin known 
as Ares Vallis, Pathfinder will touch down on July 4, 1997.

     Twenty-four hours before Mars arrival, the spacecraft will 
turn approximately 7 degrees to its entry attitude and continue 
to descend, Manning said. Hitting the thin upper atmosphere at 
more than 27,000 kilometers per hour (about 17,000 miles per 
hour), the lander's heat shield will slow the craft to about 
1,450 kilometers per hour (900 miles per hour) in about two 
minutes. An onboard computer will sense the slow-down in speed 
and eject a large parachute.  

     Seconds later, the heat shield, still red hot from the heat 
of entry, will be released and the lander will be separated from 
the backshell on a bridle. Because the rarefied atmosphere of 
Mars is only 1/100th as dense as Earth's, the parachute will slow 
the lander to about 250 kilometers per hour (155 miles per hour).  
A few seconds before impact, a giant cocoon of air bags will be 
inflated and the rockets will fire to literally stop the lander 
in mid-air and slow it to less than 72 kilometers per hour (45 
miles per hour). 

     Landing four hours before sunrise, Pathfinder will bounce 
along the Martian surface like a huge beach ball before coming to 
a halt. The craft will spend the next three hours deflating and 
retracting its air bags, standing itself upright and unfolding 
its petals to expose the 10-kilogram (22-pound) Sojourner rover. 
Daylight will give Sojourner the solar power it will need to 
power up, rise to its full height and drive off one of the two 
exit ramps onto the Martian surface.

     Although Pathfinder is considered an engineering 
demonstration, it will accomplish a focused set of science 
investigations with a stereo, multi-colored lander imager, 
atmospheric instruments that will be used as a weather station 
after landing, and an autonomous rover capable of measuring the 
composition of rocks and surface materials near the landing site. 
Sojourner will also perform mobility tests and image its 
surroundings. One of its first jobs will be to image the lander, 
so that scientists and engineers can determine the lander's 
condition and study the local terrain. 

     The Pathfinder lander will carry out most of its engineering 
objectives within the first few hours after landing, then be used 
to take panoramic images of the Martian landscape and support 
rover activities. The lander, the first in NASA's Discovery 
program of low-cost planetary spacecraft with highly focused 
science goals, has a mission lifetime of at least 30 days. 
Sojourner is expected to rove the surface of Mars for a minimum 
of seven days.  

     The Mars Pathfinder mission is managed by the Jet Propulsion 
Laboratory for NASA's Office of Space Science, Washington, D.C.

#####

1/23/95 DEA
#9606 



1