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^[1] and because it only addresses transportation to Mars and not the problem of sustaining human life there.

Background

Growth of private spaceflight

Main articles: History of SpaceX and Private spaceflight

 

Elon Musk's Tesla Roadster in space with Earth as the background, launched by the Falcon Heavy test flight

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.^[2] Musk initially attempted to acquire a Dnepr ICBM for the project through Russian contacts from Jim Cantrell.^[3] 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.^[4] 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.^[5] This led to the formation of SpaceX.^{[6]: 30–31}

Reusable launch system

 

Two Falcon Heavy boosters landing at Cape Canaveral, Florida in the Falcon Heavy test flight

This section is an excerpt from SpaceX reusable launch system development program.[edit]

SpaceX has privately funded the development of orbital launch systems that can be reused many times, similar to the reusability of aircraft. SpaceX has developed technologies over the last decade to facilitate full and rapid reuse of space launch vehicles. The project's long-term objectives include returning a launch vehicle first stage to the launch site within minutes and to return a second stage to the launch pad following orbital realignment with the launch site and atmospheric reentry in up to 24 hours. SpaceX's long term goal would have been reusability of both stages of their orbital launch vehicle, and the first stage would be designed to allow reuse a few hours after return.^[7] Development of reusable second stages for Falcon 9 was later abandoned in favor of the development of Starship,^[8] however, SpaceX has been developing reusable payload fairings for the Falcon 9.^[9]

The program was announced in 2011. SpaceX first achieved a successful landing and recovery of a first stage in December 2015. The first re-flight of a landed first stage occurred in March 2017^[9] with the second occurring in June 2017, that one only five months after the maiden flight of the booster.^[10] The third attempt occurred in October 2017 with the SES-11/EchoStar-105 mission. Reflights of refurbished first stages then became routine. In May 2021, B1051 became the first booster to launch ten missions.^[11]

The reusable launch system technology was initially developed for the first stage of Falcon 9.^[12] After stage separation, the booster flips around (an optional boostback burn reverses its course), a reentry burn controls direction to the landing site, and a landing burn accomplishes the final low-altitude deceleration and touchdown.

SpaceX planned from at least 2014 to develop reusable second stages, a more challenging engineering problem because the vehicle is travelling at orbital velocity.^[13][12][14] Second stage reuse is considered vital to Elon Musk's plans for settlement of Mars. Initial concepts for a reusable Falcon 9 second stage have been abandoned.^[8]

As of 2023^[update], SpaceX is developing the Starship system with a fully-reusable two-stage launch vehicle, intended to replace all of its other launch vehicles and spacecraft for satellite delivery and human transport—Falcon 9, Falcon Heavy and Dragon—and eventually support flights to the Moon and Mars. It could theoretically be used for point-to-point transportation on Earth.^[15]

Tenets

Further information: Space and survival, Life on Mars, and Space launch market competition

As early as 2007, Elon Musk stated a personal goal of eventually enabling human exploration and settlement of Mars,^[16] although his personal public interest in Mars goes back at least to 2001 at the Mars Society.^{[6]: 30–31} SpaceX has stated its goal is to colonize Mars to ensure the long-term survival of the human species.^[1]

Starship's reusability is expected to reduce launch costs, expanding space access to more payloads and entities.^[17] 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.^{[6]: 25, 26} Lower cost to space may potentially make space research profitable, allowing major advancements in medicine, computers, material science, and more.^{[6]: 47, 48} 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.^[18]

Launch vehicle

Main article: SpaceX Starship

 

Starship prototype assembled and stacked at Boca Chica

Starship is designed to be a fully reusable and orbital rocket, aiming to drastically reduce launch costs and maintenance between flights.^[19]: 2 The rocket consists of a Super Heavy first stage booster and a Starship second stage spacecraft,^[20] powered by Raptor and Raptor Vacuum engines.^[21] Both the rocket stages' body are made from stainless steel, giving Starship its shine and strength for atmospheric entry.^[22]

Methane was chosen for the Raptor engines because it is relatively cheap, produces low amount of soot as compared to other hydrocarbons,^[23] and can be created on Mars from carbon dioxide from the atmosphere and hydrogen via the Sabatier reaction.^[24] The engine family uses a new alloy for the main combustion chamber, allowing it to contain 300 bar (4,400 psi) of pressure, the highest of all current engines.^[23] In the future, it may be mass-produced^[23] and cost about $230,000 per engine or $100 per kilonewton.^[25]

Starship is the launch vehicle's second stage and will serve as a long-duration spacecraft on some missions.^[26] The spacecraft is 50 m (160 ft) tall^[27] and has a dry mass of less than 100 t (220,000 lb).^[25] Starship's payload volume is about 1,000 m³ (35,000 cu ft),^[28] larger than the International Space Station's pressurized volume by 80 m³ (2,800 cu ft),^[29] and can be even bigger with an extended 22 m (72 ft)-tall volume.^[30]: 2 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.^[30]: 5

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.^[31][32] A successful colonization, meaning an established human presence on Mars growing over many decades, would ultimately involve many more economic actors than SpaceX.^[33][34][35] Musk has made many tentative predictions about the date of Starship's first Mars landing,^[22] including 2029.^[36]

Exploration

 

A scene of astronauts on Mars in the 2016 IAC presentation

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.^[37] The company plans to process resources on Mars into fuel for return journeys,^[38] and use similar technologies on Earth to create carbon-neutral propellant.^[39]

Colonization and terraforming

 

Artist's conception of the process of terraforming Mars

The program aims to send a million people to Mars, using a thousand Starships sent during a Mars launch window.^[40] Proposed journeys would require 80 to 150 days of transit time,^[35] with averaging approximately 115 days (for the nine synodic periods occurring between 2020 and 2037).^[41]

Red Dragon capsule

 

Artist's conception of two Red Dragon capsules on Mars, next to an outpost

This section is an excerpt from SpaceX Red Dragon.[edit]

The SpaceX Red Dragon was a 2011–2017 concept for using an uncrewed modified SpaceX Dragon 2 for low-cost Mars lander missions to be launched using Falcon Heavy rockets.

The primary objective of the initial Red Dragon mission was to test techniques and technology to enter the Martian atmosphere with equipment that a human crew could conceivably use.^[42][43] The series of Mars missions were to be technology pathfinders for the much larger SpaceX Mars colonization architecture that was announced in September 2016.^[44] An additional suggested use for a mission called for a sample return Mars rover to be delivered to the Martian surface.

The program was conceived in 2011 as a potential NASA Discovery mission launching as early as 2022, and evolved over several years once it did not receive NASA funding from the 2013–2015 Discovery Mission program cycle. In April 2016, SpaceX announced that they had signed an unfunded Space Act Agreement with NASA, providing technical support, for a launch no earlier than 2018. In February 2017, SpaceX noted this launch date was delayed to no earlier than 2020. In July 2017, Elon Musk announced that development would be halted and resources redirected to Starship.^[45]

Starship design process

Before settling on Starship in 2018, SpaceX successively presented a number of reusable super-heavy lift vehicle proposals.^[46][47] These preliminary designs were known under various names (Mars Colonial Transporter, Interplanetary Transport System, BFR).

Early heavy-lift concepts

 

Diameter of Falcon 9 v1.0 (2010), Falcon 9 v1.1 (2013), and Mars Colonial Transporter (2014) with human to scale

In November 2005,^[48] before SpaceX launched the Falcon 1, its first rocket,^[49] CEO Elon Musk first referenced a long-term and high-capacity rocket concept named BFR. The BFR would be able to launch 100 t (220,000 lb) 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.^[48]

In July 2010,^[50] after the final launch of Falcon 1 a year prior,^[51] 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 was the Falcon XX with a 140 t (310,000 lb) capacity to low Earth orbit. To deliver such payload, the rocket would have been as tall as the Saturn V and use six powerful Merlin 2 engines.^[50] Around 2012,^[52] the company first mentioned the Mars Colonial Transporter rocket concept in public. It was going to be able to carry 100 people or 100 t (220,000 lb) of cargo to Mars and powered by methane-fueled Raptor engines.^[53]

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.^[54] He referred to this new launch vehicle under the unspecified acronym "MCT",^[54] reveled to stand for "Mars Colonial Transporter" in 2013.^[55] 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).^{[56][better source needed]} 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.^[57] SpaceX COO Gwynne Shotwell gave a potential payload range between 150-200 tonnes to low Earth orbit for the planned rocket.^[54] According to SpaceX, the MCT was to be "going to be much bigger [than Falcon 9]".^[56][58] In February 2014, the planned principal payload for the MCT was announced to be a large interplanetary spacecraft, designed to carry up to 100 tonnes (220,000 lb) of passengers and cargo.^[59] According to SpaceX engine development head Tom Mueller, SpaceX could use nine Raptor engines on a single MCT booster or spacecraft.^[60][61] The preliminary rocket design was to be at least 10 meters (33 ft) in diameter and was expected to have up to three cores totaling at least 27 booster engines.^[57]

Interplanetary Transport System

 

SpaceX illustration of the 2016 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.^[62] 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.^[63][64] 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.^[65] 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.^[66]

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.^[67] Both propellants enter the combustion chamber completely in the gas phase.^[57] 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.^[68][69][63]

The overall launch vehicle height, (first and second stages), was to be 122 m (400 ft).^[70] 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.^[68][69] Gross liftoff mass was to be 10,500 t (23,100,000 lb) at a lift-off thrust of 128 meganewtons (29,000,000 lbf). ITS was planned to be able to carry a payload to low Earth orbit of 550 tonnes (1,210,000 lb) in expendable-mode and 300 tonnes (660,000 lb) in reusable mode.^[71]

 

2016 artist's concept of the ITS booster returning to the launch pad

The ITS booster was to be a 12 m-diameter (39 ft), 77.5 m-high (254 ft), reusable first stage powered by 42 engines, each producing 3,024 kilonewtons (680,000 lbf) of thrust. Total booster thrust would have been about 128 MN (29,000,000 lbf) at liftoff, increasing to 138 MN (31,000,000 lbf) in a vacuum,^[72]several times the 36 MN (8,000,000 lbf) thrust of the Saturn V.^[68] It weighed 275 tonnes (606,000 lb) when empty and 6,700 tonnes (14,800,000 lb) when completely filled with propellant. It would have used grid fins to help guide the booster through the atmosphere for a precise landing.^[72] 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.^[69]

On 26 September 2016, a day before the 67th International Astronautical Congress, the Raptor engine fired for the first time.^[73] 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 300 t (660,000 lb) 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.^[74] The concept, especially the technological feats required to make such a system possible and the funds needed, garnered a large amount of skepticism.^[75]

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.^[69]

The design goal was to achieve a separation velocity of about 8,650 km/h (5,370 mph) while retaining about 7% of the initial propellant to achieve a vertical landing at the launch pad.^[69][76]The design called for grid fins to guide the booster during atmospheric reentry.^[69] 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.^[77] The booster was to be designed for 20 g nominal loads, and possibly as high as 30–40 g.^[77]

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.^[69]

 

2016 artist concept of the ITS Interplanetary Spaceship, in orbit near the rings of Saturn

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.^[68] Its maximum width was to be 17 m (56 ft), 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 31 MN (7,000,000 lbf).^[78]

• 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 450 tonnes (990,000 lb) per trip to Mars following refueling in Earth orbit.^[68] Its three sea-level Raptor engines were designed to be used for maneuvering, descent, landing, and initial ascent from the Mars surface.^[68] It would have had a maximum capacity of 1,950 tonnes (4,300,000 lb) of propellant, and a dry mass of 150 tonnes (330,000 lb).^[78]
• The ITS tanker, a second stage propellant tanker variant design. It aimed to transport up to 380 tonnes (840,000 lb) of propellants to low Earth orbit to refuel Interplanetary Spaceships. After refueling operations, it was to land and be prepared for another flight.^[71] It had a maximum capacity of 2,500 tonnes (5,500,000 lb) of propellant and had a dry mass of 90 tonnes (200,000 lb). ^[78]

Big Falcon Rocket

 

2018 artist's conception of the redesigned BFR/Starship at stage separation

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.^[79] 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.^[59] Musk foresaw the first two cargo missions to Mars as early as 2022,^[80] 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.^[79]

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.^[79]

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 20 MPa (200 bar; 2,900 psi). The flight engine aimed for 25 MPa (250 bar; 3,600 psi), on the way to 30 MPa (300 bar; 4,400 psi) in later iterations.^[79] In November 2017, Shotwell indicated that about half of all development work on BFR was focused on the engine.^[81]

SpaceX looked for manufacturing sites in California, Texas, Louisiana,^[82] and Florida.^[83] 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.]"^[79]

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.^[84]

In March, SpaceX announced that it would manufacture its launch vehicle and spaceship at a new facility on Seaside Drive at the port.^[85][86][87] By May, about 40 SpaceX employees were working on the BFR.^[82] SpaceX planned to transport the launch vehicle by barge, through the Panama Canal, to Cape Canaveral for launch.^[82] 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 150 t (330,000 lb) of cargo anywhere in the world in under 30 minutes, for "less than the cost of a C-5".^[88][89]

The BFR was designed to be 106 meters (348 ft) tall, 9 meters (30 ft) in diameter, and made of carbon composites.^[80][90] 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.^{[80][79]: 18:05–19:25} 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.^[91][a]

Three BFS versions were described: BFS cargo, BFS tanker, and BFS crew. The cargo version was to be used to reach Earth orbit^[80] 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.^{[80][79]: 31:50} The BFR also aimed to carry passengers/cargo in Earth-to-Earth transport, delivering its payload anywhere within 90 minutes.^[80]

Reception and feasibility

As of December 2023, SpaceX has not publicly detailed plans for the spacecraft's life-support systems, radiation protection, and in situ resource utilization, which are essential for space colonization.^[92]

Notes

1. "Still ensuring capability if one of the engine fails" is what the source means by "engine-out capability".

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External links

• Official website