SpaceX founder and CEO Elon Musk plans to send the first colonists to Mars around 2024, although he acknowledges in a new article for the journal New Space that the deadline might be ambitious.
Future astronauts would ride there on SpaceX's forthcoming Big Falcon Rocket (BFR). The rocket will eventually replace the entire line of rockets that SpaceX now flies — the Falcon 9 and the Falcon Heavy. The latter rocket type was first tested in February.
"We are targeting our first cargo missions in 2022 — that’s not a typo, although it is aspirational," Musk wrote. "We’ve already started building the system. The tooling for the main tanks has been ordered, the facility is being built and we will start construction of the first ship around the second quarter of next year. In about six to nine months, we should start building the first ship."
By 2024, SpaceX hopes to send four ships to Mars: two cargo ships and two crewed missions. The first mission in 2022 will search for harvestable water, and the second mission will build a propellant plant, partly using resources left behind by previous ships.
"The base starts with one ship, then multiple ships, then we start building out the city and making the city bigger, and even bigger,” Musk wrote. “Over time, [they are] terraforming Mars and making it really a nice place to be.”
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In the article, Musk relates recent SpaceX progress with the BFR, such as upping the company's rocket launch rate and improving its rockets' ability to land. "Falcon 9 can also land with very high precision,” Musk said. “In fact, we believe the precision at this point is good enough that we will not need legs for the next version. It will literally land with so much precision that it will land back on its launch mounts.”
The company's next version of the Dragon spacecraft, which carries cargo to the International Space Station (ISS) and will soon transport astronauts as well, will no longer be equipped with the robotic Canadarm that attaches the ship to the orbiting complex, Musk added. Instead, Dragon will dock directly with the station.
Musk said as design of the rocket has progressed, SpaceX has reduced its size compared to previous plans. The BFR will likely have a payload capacity of 150 tons in low Earth orbit — five times the capability of the Falcon Heavy. The ship it will carry will be an astounding 48 meters (157 feet) long, which is half the width of the ISS. A ship destined for Mars will need to fit 100 people.
"In a Mars transit configuration, since you would be taking three months in a really good scenario but maybe as much as six months, you probably want a cabin, not just a seat," Musk wrote. "The Mars transit configuration consists of 40 cabins. You could conceivably have five or six people per cabin if you really wanted to crowd people in, but I think mostly we would expect to see two to three people per cabin, or about a hundred people per flight to Mars."
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The BFR's propellant is a mix of methane and oxygen, which could be replenished by a tanker ship once in space. Musk said this will save money and make refueling less complicated.
"If you just fly BFR to orbit and do not do any refilling, it is pretty good — you’ll get 150 tons to low Earth orbit, and have no fuel to go anywhere else," Musk wrote. "However, if you send up tankers and refill in orbit, you can refill the tanks all the way to the top and get 150 tons all the way to Mars. And if the tanker has high reuse capability, then you are just paying for the cost of propellant — the cost of oxygen and the cost of methane is extremely low."
For a Mars mission, the BFR would launch, refill its tanks, voyage to Mars, and then touch down on the surface.
Propellant on Mars could be manufactured on site using the planet's abundant oxygen and water, which can be transformed into the methane and oxygen the BFR needs.
While Musk's ultimate destination is Mars, he said the BFR could be used to launch satellites and telescopes, or carry cargo to the ISS. It might also be used in lunar missions, a priority of the Trump administration.