Starship to be refuelled in space 14 times before a trip to the Moon

28. februar kl. 16:08
Starship to be refuelled in space 14 times before a trip to the Moon
SpaceX conducted a crucial engine test of Starship’s booster rocket on 3 February. 31 out of 33 engines fired. One engine was turned off before starting and another turned off on its own during the test. Thus, there is a good chance that we will see Starship fly in the coming months. Illustration: Ingeniøren.
Over the course of six months, fuel will be transported up to the Starship lunar lander while it orbits Earth. Refuelling is the future, according to a Danish professor.
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SpaceX’s Starship is currently preparing for its first orbit around Earth—and there is good reason to practice for that particular flight.

Because when Starship, commissioned by NASA, goes on the mission to land astronauts on the Moon in a few years, the lunar lander will have to spend up to six months in orbit in order to be fully fuelled for the trip.

“Starship is far from an optimal design for Moon landing. But it was not originally built for that either. It was built to transport many people and material to Mars. And that will require a vessel of that size,” says John Leif Jørgensen, professor at DTU Space.

And its size is precisely the reason why Starship—in contrast to Apollo 11, which was the first spaceflight that landed on the Moon back in 1969—cannot just fly to the Moon immediately. Without fuel and equipment, Starship weighs a whopping 125 tonnes, which is almost 30 times more than Apollo 11’s lunar lander.

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Facts: Starship’s first orbital flight

After almost two years without flights, there is now a prospect of new SpaceX Starship test flights. Starship has flown seven times, but never on top of its booster rocket. It is expected to happen in the coming months. The launch will take place in Florida, and Starship is expected to land in the ocean northwest of the island of Kauai, Hawaii. The flight will last 90 minutes.

And it will probably end up being even heavier in the end, because SpaceX has not presented the exact weight calculations for a Starship with tiles, electronic equipment, and an expected load of up to 150 tonnes. SpaceX estimates that 1,200 tonnes of fuel (liquid oxygen and methane) must be used to complete a lunar landing—and not least to be able to leave the Moon again.

This means that Starship has to be refuelled a total of 14 times in orbit to have enough fuel. During a launch, Starship uses most of its fuel to reach orbit after separation from the booster rocket.

“Refuelling missions are something we will see more of in the future. But it’s luckily also a relatively simple manoeuvre when it takes place in low Earth orbit,” John Leif Jørgensen says.

The refuelling of Starship in orbit around Earth will probably be done by two vessels meeting at their tails. Refuelling can be carried out when the vessels accelerate slightly using the manoeuvring thrusters. A concept where the vessels meet side by side is also on the drawing board. Illustration: Ingeniøren.

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The information that Starship will require 14 refuelling missions comes from a report that SpaceX itself has submitted to the U.S. authorities. It also states that the refuelling missions will be around 12 days apart.

However, Elon Musk has since stated that the 14 refuelling missions are a conservative estimate. The refuelling could be done in eight missions, possibly four if Starship is only filled up to half and if the flaps and the heat shield are dropped.

Exactly how the refuelling will take place is unknown, but SpaceX has shown illustrations where two vessels meet at their tails and side by side.

Each refuelling increases the risks

The large number of refuelling missions has been met with criticism from competitor Blue Origin, which long sought the task of building a lunar lander for NASA—until the space agency closed the door on it.

Blue Origin’s criticism was mainly that the risk of the Moon mission would increase due to the number of missions. And John Leif Jørgensen agrees with that in principle:

“It’s clear that while the success rate for each mission is good, the risk to the overall mission increases the more refuelling you have to do. If one or more launches are postponed, this also makes the travel time uncertain. This could be a problem for the overall planning of a mission with people on or around the Moon,” John Leif Jørgensen says.

So far, the plan for a lunar mission with NASA is for NASA to fly astronauts into orbit around the Moon with the SLS rocket and the Orion capsule. A fully fuelled Starship will then follow, and two astronauts will be transferred to the Starship, which will land on the Moon and later rejoin Orion, which will take the astronauts home.

What will happen with the Starship afterwards is not yet determined.

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According to John Leif Jørgensen, there has been a growing focus on research into refuelling in space in recent years, and NASA has made a financial contribution to SpaceX’s research in the area, which, among other things, takes place in collaboration with NASA’s Marshall Space Flight Center, where nozzles or couplings that make it possible to transfer liquid oxygen and methane in space are designed.

SpaceX just completed the first static test of the booster rocket, and 31 out of 33 engines fired. That is enough to reach orbit, and thus a launch in March is now a possibility.

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