SpaceX ambition of colonizing Mars

SpaceX ambition of colonizing Mars
SpaceX has stated its ambition to facilitate the colonization of Mars via the development of the Starship launch vehicle. The company claims that this is necessary for the long-term survival of the human species and that its Mars program will reduce space transportation costs, thereby making travel to Mars a more realistic possibility.
Elon Musk, who founded SpaceX, first presented his goal of enabling Mars colonization in 2001 as a member of the Mars Society's board of directors. In the 2000s and early 2010s, SpaceX made many vehicle concepts for delivering payloads and crews to Mars, including space tugs, heavy-lift launch vehicles, and Red Dragon capsules. The company's current Mars plan was first formally proposed at the 2016 International Astronautical Congress alongside a fully-reusable launch vehicle, the Interplanetary Transport System. Since then, the launch vehicle proposal was altered and renamed to "Starship", and has been in development since. The company has given many estimates of dates of the first human landing on Mars.
SpaceX plans for early missions to Mars to involve small fleets of Starship spacecraft, funded by public–private partnerships. The company hopes that once infrastructure is established on Mars and the launch cost is reduced further, colonization can begin. The hypothetical Mars program has been criticized as impractical, both because of uncertainties regarding its financing and because it only addresses transportation to Mars and not the problem of sustaining human life there.
Background
Growth of private spaceflight
Before founding SpaceX, Musk joined the Mars Society's board of directors for a short time. He was offered a plenary talk at their convention where he announced Mars Oasis, a project to land a miniature experimental greenhouse and grow plants on Mars, to revive public interest in space exploration. Musk initially attempted to acquire a Dnepr ICBM for the project through Russian contacts from Jim Cantrell. Russian officials were unreceptive to Musk's approach and on the flight back from Moscow, Musk worked on a spreadsheet and concluded that they could build their own rockets. Over time, Musk's goal evolved from a small publicity mission to generate interest in going to Mars, to a full-scale effort to create an architecture that would enable a self-sustaining human settlement on Mars. This led to the formation of SpaceX.
Reusable launch system
Tenets
As early as 2007, Elon Musk stated a personal goal of eventually enabling human exploration and settlement of Mars, although his personal public interest in Mars goes back at least to 2001 at the Mars Society. SpaceX has stated its goal is to colonize Mars to ensure the long-term survival of the human species.
Starship's reusability is expected to reduce launch costs, expanding space access to more payloads and entities. According to Robert Zubrin, aerospace engineer and advocate for human exploration of Mars, Starship's lower launch cost would make space-based economy, colonization, and mining practical. Lower cost to space may potentially make space research profitable, allowing major advancements in medicine, computers, material science, and more. Musk has stated that a Starship orbital launch will cost less than $2 million. Pierre Lionnet, director of research at Eurospace, claimed otherwise, citing the rocket's multi-billion-dollar development cost and its current lack of external demand.
Launch vehicle
Starship is designed to be a fully reusable and orbital rocket, aiming to drastically reduce launch costs and maintenance between flights. The rocket consists of a Super Heavy first stage booster and a Starship second stage spacecraft, powered by Raptor and Raptor Vacuum engines. Both the rocket stages' body are made from stainless steel, giving Starship its shine and strength for atmospheric entry.
Methane was chosen for the Raptor engines because it is relatively cheap, produces low amount of soot as compared to other hydrocarbons, and can be created on Mars from carbon dioxide from the atmosphere and hydrogen via the Sabatier reaction. The engine family uses a new alloy for the main combustion chamber, allowing it to contain of pressure, the highest of all current engines. In the future, it may be mass-produced and cost about $230,000 per engine or $100 per kilonewton.
Starship is the launch vehicle's second stage and will serve as a long-duration spacecraft on some missions. The spacecraft is tall and has a dry mass of less than . Starship's payload volume is about , larger than the International Space Station's pressurized volume by , and can be even bigger with an extended -tall volume. By refueling the Starship spacecraft in orbit using tanker spacecraft, Starship will be able to transport larger payloads and more astronauts to other Earth orbits, to the Moon (Starship HLS), and Mars.
Program manifest
SpaceX plans to build a crewed base on Mars for an extended surface presence, which it hopes will grow into a self-sufficient colony. A successful colonization, meaning an established human presence on Mars growing over many decades, would ultimately involve many more economic actors than SpaceX. Musk has made many tentative predictions about the date of Starship's first Mars landing, including 2029.
Exploration
Musk plans for the first crewed Mars missions to have approximately 12 people, with the goals of "build[ing] out and troubleshoot[ing] the propellant plant and Mars Base Alpha power system" and establishing a "rudimentary base." He has claimed that, in the event of an emergency during travel, the spaceship would be able to safely return to Earth. The company plans to process resources on Mars into fuel for return journeys, and use similar technologies on Earth to create carbon-neutral propellant.
Colonization and terraforming
The program aims to send a million people to Mars, using a thousand Starships sent during a Mars launch window. Proposed journeys would require 80 to 150 days of transit time, with averaging approximately 115 days (for the nine synodic periods occurring between 2020 and 2037).
Prior launch vehicle proposals
Before finally settling on Starship in 2018, SpaceX successively presented a number of reusable super-heavy lift vehicle proposals.
Early heavy-lift concepts
In November 2005, before SpaceX launched the Falcon 1, its first rocket, CEO Elon Musk first referenced a long-term and high-capacity rocket concept named BFR. The BFR would be able to launch to low Earth orbit and equipped with Merlin 2 engines. The Merlin 2 is in direct lineage to the Merlin engines used in the Falcon 9 and comparable to the F-1 engines used in the Saturn V.
In July 2010, after the final launch of Falcon 1 a year prior, SpaceX presented launch vehicle and Mars space tug concepts at a conference. The launch vehicle concepts were called Falcon X, Falcon X Heavy, and Falcon XX; the largest of all is the Falcon XX with a capacity to low Earth orbit. To deliver such payload, the rocket was going to be as tall as the Saturn V and use six powerful Merlin 2 engines. Around 2012, the company first mentioned the Mars Colonial Transporter rocket concept in public. It was going to be able to carry 100 people or of cargo to Mars and powered by methane-fueled Raptor engines.
Mars Colonial Transporter
In October 2012, Musk made the first public articulation of plans to develop a fully reusable rocket system with substantially greater capabilities than SpaceX's existing Falcon 9. This new launch vehicle was intended to be part of the company's Mars system architecture, then known as the Mars Colonial Transporter/Mass Cargo Transport (MCT). According to SpaceX, the MCT system would include reusable rocket engines, launch vehicles and space capsules that would enable transportation of humans to Mars and back to Earth. SpaceX COO Gwynne Shotwell gave a potential payload range between 150-200 tonnes to low Earth orbit for the planned rocket. According to SpaceX, the MCT was to be "going to be much bigger [than Falcon 9]". In February 2014, the planned principal payload for the MCT was announced to be a large interplanetary spacecraft, designed to carry up to of passengers and cargo. According to SpaceX engine development head Tom Mueller, SpaceX could use nine Raptor engines on a single spacecraft. The preliminary rocket design was to be at least in diameter and was expected to have up to three cores totaling at least 27 booster engines.
Red Dragon capsule
Interplanetary Transport System
In 2016, Musk changed the name of the Mars Colonial Transporter system to the Interplanetary Transport System (ITS), as he intended for the system to be capable of traveling beyond Mars. That same year he provided more details about the space mission architecture, launch vehicle, spacecraft, and Raptor engines. The first test firing of a Raptor engine on a test stand took place in September 2016. In October 2016, Musk indicated that the initial tank test article, made out of carbon-fiber pre-preg, and built with no sealing liner, had performed well in cryogenic fluid testing. A pressure test at about 2/3 of the design burst pressure was completed in November 2016. In July 2017, Musk indicated that the architecture design had evolved since 2016 in order to support commercial transport via Earth-orbit and cislunar launches.
The ITS stack was to be composed of two stages, both powered by Raptor engines. A first stage booster, and a second stage that was to be either an "Interplanetary Spaceship" for crewed transport or an "ITS tanker" for orbital refueling. By that point, Raptor was a rocket engine in a full flow staged combustion cycle, with liquid methane fuel and liquid oxygen oxidizer. Both propellants enter the combustion chamber completely in the gas phase. A bleed-off of the high-pressure gas would provide autogenous pressurization of the propellant tanks, eliminating the Falcon 9's problematic high-pressure helium pressurization system.
The overall launch vehicle height, (first and second stages), was to be . Both stages were to have been constructed of carbon fiber, including the cryogenic propellant tanks, a major change for SpaceX from the Falcon 9's aluminum-lithium alloy tank and structure material. Both stages were to be fully reusable and were to land vertically. Gross liftoff mass was to be at a lift-off thrust of . ITS was planned to be able to carry a payload to low Earth orbit of in expendable-mode and in reusable mode.
The ITS booster was to be a reusable first stage powered by 42 engines, each producing of thrust. Total booster thrust would have been about at liftoff, increasing to in a vacuum,several times the thrust of the Saturn V. It weighed when empty and when completely filled with propellant. It would have used grid fins to help guide the booster through the atmosphere for a precise landing. The engine configuration included 21 engines in an outer ring and 14 in an inner ring. The center cluster of seven engines was to be gimbaled for directional control, although some directional control was to be performed via differential thrust on the fixed engines. Thrust on each engine was aimed to vary between 20 and 100 percent of rated thrust.
On 26 September 2016, a day before the 67th International Astronautical Congress, the Raptor engine fired for the first time. At the event, Musk announced SpaceX was developing a new rocket using Raptor engines called the Interplanetary Transport System. It would have two stages, a reusable booster and spacecraft. The stages' tanks were to be made from carbon composite, storing liquid methane and liquid oxygen. Despite the rocket's launch capacity to low Earth orbit, it was expected to have a low launch price. The spacecraft featured three variants: crew, cargo, and tanker; the tanker variant is used to transfer propellant to spacecraft in orbit. The concept, especially the technological feats required to make such a system possible and the funds needed, garnered a large amount of skepticism.
The main propellants, in gaseous phase, were to also power the reaction control thrusters. These thrusters are intended to control booster orientation in space and improve accuracy during landing.
The design goal was to achieve a separation velocity of about while retaining about 7% of the initial propellant to achieve a vertical landing at the launch pad.The design called for grid fins to guide the booster during atmospheric reentry. The booster return flights were expected to encounter loads lower than the Falcon 9, principally because the ITS would have both a lower mass ratio and a lower density. The booster was to be designed for 20 g nominal loads, and possibly as high as 30–40 g.
In contrast to the landing approach used on SpaceX's Falcon 9—either a large, flat concrete pad or downrange floating landing platform, the ITS booster was to be designed to land on the launch mount itself, for immediate refueling and relaunch.
The ITS second stage was planned to be used for long-duration spaceflight, instead of solely being used for reaching orbit. The two proposed variants aimed to be reusable. Its maximum width was to be , with three sea level optimised Raptor engines and six with greater efficiency in the vacuum of space. Total engine thrust in a vacuum was to be about .
The Interplanetary Spaceship, a large passenger-carrying spacecraft design proposed in September 2016. The ship would have operated as a second-stage and interplanetary transport vehicle for cargo and passengers. It aimed to transport up to per trip to Mars following refueling in Earth orbit. Its three sea-level Raptor engines were designed to be used for maneuvering, descent, landing, and initial ascent from the Mars surface. It would have had a maximum capacity of of propellant, and a dry mass of 150 tonnes (330,000 lb).
The ITS tanker, a second stage propellant tanker variant design. It aimed to transport up to of propellants to low Earth orbit to refuel Interplanetary Spaceships. After refueling operations, it was to land and be prepared for another flight. It had a maximum capacity of of propellant and had a dry mass of .
Big Falcon Rocket
In September 2017, at the 68th annual meeting of the International Astronautical Congress, Musk announced a new launch vehicle calling it the BFR, again changing the name, though stating that the name was temporary. The acronym was alternatively stated as standing for Big Falcon Rocket or Big Fucking Rocket, a tongue-in-cheek reference to the BFG from the Doom video game series. Musk foresaw the first two cargo missions to Mars as early as 2022, with the goal to "confirm water resources and identify hazards" while deploying "power, mining, and life support infrastructure" for future flights. This would be followed by four ships in 2024, two crewed BFR spaceships plus two cargo-only ships carrying equipment and supplies for a propellant plant.
The design balanced objectives such as payload mass, landing capabilities, and reliability. The initial design showed the ship with six Raptor engines (two sea-level, four vacuum) down from nine in the previous ITS design.
By September 2017, Raptors had been test-fired for a combined total of 20 minutes across 42 test cycles. The longest test was 100 seconds, limited by the size of the propellant tanks. The test engine operated at . The flight engine aimed for , on the way to in later iterations. In November 2017, Shotwell indicated that about half of all development work on BFR was focused on the engine.
SpaceX looked for manufacturing sites in California, Texas, Louisiana, and Florida. By September 2017, SpaceX had started building launch vehicle components: "The tooling for the main tanks has been ordered, the facility is being built, we will start construction of the first ship [in the second quarter of 2018.]"
By early 2018, the first carbon composite prototype ship was under construction, and SpaceX had begun building a new production facility at the Port of Los Angeles.
In March, SpaceX announced that it would manufacture its launch vehicle and spaceship at a new facility on Seaside Drive at the port. By May, about 40 SpaceX employees were working on the BFR. SpaceX planned to transport the launch vehicle by barge, through the Panama Canal, to Cape Canaveral for launch. Since then, the company has pivoted and terminated the agreements to do this.
In August 2018, the head of the US Air Force Air Mobility Command expressed interest in the ability of the BFR to move up to of cargo anywhere in the world in under 30 minutes, for "less than the cost of a C-5".
The BFR was designed to be tall, in diameter, and made of carbon fiber. The upper stage, known as Big Falcon Ship (BFS), included a small delta wing at the rear end with split flaps for pitch and roll control. The delta wing and split flaps were said to expand the flight envelope to allow the ship to land in a variety of atmospheric densities (vacuum, thin, or heavy atmosphere) with a wide range of payloads. The BFS design originally had six Raptor engines, with four vacuum and two sea-level. By late 2017, SpaceX added a third sea-level engine (totaling 7) to allow greater Earth-to-Earth payload landings and still ensure capability if one of the engines fails.
Three BFS versions were described: BFS cargo, BFS tanker, and BFS crew. The cargo version was to be used to reach Earth orbit as well as carry cargo to the Moon or Mars. After refueling in an elliptical Earth orbit, BFS was designed to eventually be able to land on the Moon and return to Earth without another refueling. The BFR also aimed to carry passengers/cargo in Earth-to-Earth transport, delivering its payload anywhere within 90 minutes.
Reception and feasibility
SpaceX has not detailed plans for the spacecraft's life-support systems, radiation protection, and in situ resource utilization, technologies which are essential for space colonization.
Notes
References
External links
Official website
Human missions to Mars
Colonization of Mars
Space tourism
SpaceX Starship
Space program of the United States
SpaceX