Elon Musk plans to launch the prototype of a game-changing vehicle for space travel soon. The starship, as it is known, will be a fully reusable transport system, capable of transporting up to 100 people to the Red Planet.
The founding ethos of Elon Musk’s private space company, SpaceX, was to make life multiplanetary. This is partly motivated by existential threats, such as an asteroid collision large enough to wipe out humanity.
The colonization of other planets would place some of the eggs in other baskets, saving human civilization if one experienced cataclysm.
In 2016, the businessman explained his reasoning at an international conference in Mexico: “History will be divided in two directions. One way is to stay on Earth forever, and then there will be an eventual extinction event, ”he said.
“The alternative is to become a space civilization and a kind of multiple planets, which I hope you will agree is the right way to go.”
Musk has always talked about his dream of building cities on Mars. He believes that settlements would need large numbers of people to become self-sustainable.
Realizing this dream requires a vehicle that is up to the task. Starship is a combination of a rocket and a spaceship that can transport more than 100 people at a time to the Red Planet.
The system was designed to be completely reusable, that is, the main hardware elements are not discarded at sea or burned, as with some other launch systems, but are recovered from space. They can then be refurbished and transported again, reducing the cost of the entire project.
Starship: an overview
The rocket part of the system is called Super Heavy, while the spaceship part is called Starship.
The combined system will be 120 m (394 feet) high and is also known as a starship.
Let’s get the spaceship first. With its nose and landing fins, the stainless steel vehicle resembles rockets from the golden age of science fiction.
The 50 m (160 ft) long vessel, also known as the upper stage, has a huge cargo compartment close to the front that will be able to transport large loads or people to destinations in deep space.
In the middle of the ship are the propellant tanks. These feed liquid methane (CH4) and liquid oxygen (O2) to six Raptor engines at the rear of the vehicle.
Methane is the fuel and oxygen acts as an oxidizer – a chemical that makes the fuel burn. The combination is called a methalox.
The choice of fuel is unusual for rocket engines, but methane can generate a lot of thrust. It is also a prudent choice in light of the Musk projects on Mars. The founder of SpaceX says that CH4 can be synthesized from groundwater from Mars and atmospheric carbon dioxide (CO2), using a chemical process known as the Sabatier reaction.
SpaceX has spent more than a decade developing the highly efficient Raptor engine. Combustion occurs in stages and the engine design reduces the amount of propellant wasted.
Refueling the ship for the trip back to Earth using Martian resources would provide a level of self-sufficiency, making travel more viable and economical.
Now, let’s go back to the rocket. Measuring 70 m (230 feet) in length, the Super Heavy will be filled with 3,400 tons (6.8 million pounds) of cryogenic metalox (cooled).
It will be powered by about 28 Raptor engines (this specification has changed several times), providing around 16 million pounds (72 Meganewtons) of maximum thrust. It must be able to lift at least 100 tons of payload, and possibly up to 150 tons, to Earth’s low orbit.
This will make the Super Heavy more powerful than the immense Saturn V launcher used for the Apollo Moon missions in the 1960s and 70s.
How does it get to space?
As it ascends from the launch pad, the combined starship system will begin to tilt towards the intended orbit.
When the upper stage separates in space, the Super Heavy turns as it falls towards Earth.
As it descends, the Super Heavy will implant steel structures called “grid fins”, in the shape of potato waffles, on the sides of the booster. This will help to drive the rocket stage back to its launch pad so that it can land and fly again.
Previously, SpaceX wanted to run the Super Heavy’s Raptor engines to guide them to a precise landing on six steel legs. SpaceX does something similar with the early stages of its Falcon 9 rockets, safely landing them on landing platforms and drone ships after launch.
But Mr. Musk recently tweeted to say that that thought has changed. SpaceX now plans to catch the falling booster using an arm on the launch tower.
This is the structure that provides engineers and crew members with access to the spacecraft and rocket while they are sitting on the platform before launch. How exactly this “capture mechanism” will work, however, remains to be seen.
In the meantime, the starship’s upper stage can be inserted into a “parking orbit” after separation, allowing it to be refueled.
“If you just fly [Starship] to orbit and not recharge, it’s very good – you’ll get 150 tons in low Earth orbit and you won’t have the fuel to go anywhere else, ”explained Musk during a 2017 conference speech.
“If you send tanks and refuel in orbit, you can refuel the tanks to the top and get 150 tons [of payload] all the way to Mars. “
To refuel, the spacecraft would dock, or mate, with another starship – already circling Earth – which acts only as a propellant deposit.
“The two ships would mate in the rear section. They would use the same mating interface that they use to connect to the booster at takeoff,” said Musk in 2017.
“Transferring propellant becomes very simple: you use control thrusters to accelerate in the direction you want to deflate.”
What will the Starship be used for?
For long-distance trips to Mars and back and forth – which can take up to nine months each way – Musk plans to install about 40 cabins in the cargo area near the front of the upper stage.
“You could conceivably have five or six people per cabin, if you really wanted to crowd people. But I think we would expect to see two or three people per cabin, nominally about 100 people per flight to Mars,” Musk said.
The payload compartment would also house common areas, storage space, a kitchen and a shelter where people could gather to protect themselves from solar storms, where the Sun expels harmful charged particles into space.
The starship may also play a role in NASA’s Artemis program, which aims to establish a long-term human presence on the Moon. In 2020, SpaceX received $ 135 million from NASA to develop the starship project so that it could be used like a manned lunar module.
The version adapted for Artemis flights would not have the thermal shield or flaps that are necessary for a trip back to Earth. Instead, the Starship Human Landing System would remain in space after its initial launch from Earth, to be used for various trips between the lunar orbit and the lunar surface.
The uncapped, or cargo, version of Starship features a cargo compartment that opens like a crocodile’s mouth. This would allow it to be used for launching satellites. SpaceX says the enormous payload capacity opens up possibilities for new types of robotic scientific missions, including telescopes larger than the James Webb Observatory – Hubble’s next successor.
The system can even be used for high-speed travel between different destinations on Earth.
Musk says the starship could eventually transport people to destinations in the “great solar system”, including gas giants like Jupiter. But that remains a long-term goal.
How does the upper stage land?
To bring other spacecraft back to Earth, engineers relied on parachutes or designed the vehicle so that it could land on a runway.
But the top stage of the starship takes a different approach. When ready to land, the ship initially enters the atmosphere at a 60-degree angle and then “falls on its belly” to the ground in a horizontal position.
This return mode depends entirely on the atmosphere to slow the vehicle down. The disadvantage is that, in this configuration, the starship is inherently unstable.
The vehicle therefore uses four steel landing flaps, positioned close to the front and rear of the vehicle, to control its descent. It’s like a skydiver uses his arms and legs to control a free fall.
“It is very different from anything else … we are making a controlled drop,” said Elon Musk during a Starship update in 2019.
“You’re trying to create drag instead of lift – it’s really the opposite of an aircraft.”
As the spacecraft approaches the ground, it must be slow enough to perform an engine burn that turns the vehicle to an upright position. He then uses the Raptors as retro rockets to guide the vehicle to a safe landing.
Musk says this general approach could be used to safely bring down the starship on any planetary surface in the Solar System – Mars included.
When will you fly?
In recent years, SpaceX has tested several Starship upper-stage prototypes at its Boca Chica facility in Texas.
The company started with a 39-meter-high “test article” called Starhopper, which resembled a water tower. Since flying with this vehicle 150 m above the ground, SpaceX has developed increasingly complex starship prototypes.
In December 2020, SpaceX released a test article called SN8 (Starship Number 8) – the first to feature a nose and flaps. After reaching an altitude of 12.5 km, the SN8’s belly fell back to Earth, giving SpaceX valuable engineering data on the final part of the starship’s return from space.
It was almost a normal flight, but the vehicle approached the airstrip a little fast and hard, causing it to fold and explode. SpaceX has already moved the SN9 prototype to the launch pad, and this time, they intend to maintain the landing.
In October 2020, Elon Musk said that SpaceX intended to launch the Starship on an unmanned flight to Mars in 2024.
Some observers note that Musk’s deadlines are sometimes optimistic. But he also developed a reputation for eventually reaching his goals, no matter how ambitious.
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