Why SpaceX’s Starship Plans On Refilling In Orbit
SpaceX’s Starship is innovative in a lot of different ways. One unique aspect of Starship is its plan to be refilled while in orbit. One Starship will be launched and placed into orbit, soon after another will join it and dock, transferring propellant from one to the other. SpaceX is planning to do this for missions to the Moon, Mars, and beyond.
SpaceX is planning on refilling Starship in orbit to increase the amount of cargo it can carry, and ensure Starship can make the long trip to different planets. The refilling process will specifically help SpaceX with its main goal of putting humans on Mars and colonizing the planet.
While SpaceX has not tested the refueling process yet, they are making very quick progress on Starship. They have also recently changed their plan for what the refilling process might look like. With an upcoming orbital test flight, we can expect to see more tests in the near future.
What Is Starship’s Goal?
Starship has a lot of goals including carrying 100-150 tons into low Earth orbit, going to the Moon, Mars, and beyond. Each of these goals is extremely ambitious and will require a unique and innovative design to accomplish them. Specifically, one of the main goals of Starship and Elon Musk is to put humans on Mars. Additionally, he not only wants to put people on the planet but set up an entire colony. To do this SpaceX not only need a rocket that can make the trip but a rocket capable of carrying a large amount of cargo.
To set up a colony SpaceX would need to have multiple Starships filled with humans and even more Starships full of life support and other necessary equipment. This is part of the reason why SpaceX is aiming to make 100 Starships and launch 1000 Starships in a single year. This plan is far in the future and very ambitious. However, Starship’s unique and innovative design combined with SpaceX’s speed could end up making it a reality.
Why Starship Will Refill In Orbit
Starship will refill in orbit to provide a single Starship with more liquid methane and oxygen prior to leaving Earth’s orbit. The added liquid oxygen and methane will ensure Starship will have enough for the trip to other planets with a lot of cargo.
Longer Distances – With Starship planning to go to faraway celestial bodies including the Moon, Mars, and beyond, it will require a lot of fuel to get there. The Moon alone is around 240,000 miles away from Earth. Even more impressive is Mars which is a staggering 246 million miles away. While a trip to the Moon only takes a few days, a trip to Mars takes around 7 entire months. When looking at rockets, almost all the fuel for the engines is used just to get into orbit. The booster’s sole purpose is getting the second stage majority of the way up, the second stage then has to light its engines and pick up speed to get into the correct orbit.
Once finally in orbit, you are now left with a partially full second stage Starship. The reason other rockets and missions to the Moon and Mars didn’t refill is that they didn’t need to. With such small cargos and weight in comparison, the fuel left on the residual stage was enough to finish the mission. With the amount of weight Starship is expected to carry into orbit, the added fuel will ensure it can make the long journey to wherever it’s headed.
More Cargo – Starship refilling in orbit not only ensures it can make the long trip but also means the rocket can bring even more cargo to its destination. One of the biggest challenges of creating and launching rockets is trying to get as much weight into orbit and beyond as possible. This has to do with the rocket’s size, engines, fuel, power, and much more. The more cargo you can bring into orbit means the fewer trips needed for a lot of missions.
As I mentioned above, the majority of a rocket is just different fuel storage. Additionally, a large majority of the fuel is used up while getting into orbit. By SpaceX refilling Starship in orbit it means that rather than compromise and bring less weight in return for more fuel, they can take more cargo and refill in orbit. This decision will allow Starship to have a massive weight capacity during the trip to Mars if fully successful.
How Will Starship Refill In Orbit?
Starship’s plan to refill in orbit is far in the future and that’s why the plan for how SpaceX will do it has changed multiple times. At first SpaceX and Musk talked and showed animations of two Starships docking in orbit through the bottom of both second stages. The plan was to launch one into orbit then send another up and meet with the already orbiting Starship. From this point, the two rockets would connect together bottom to bottom. Once connected, one Starship would transfer liquid oxygen and methane to the other.
Recently, SpaceX and Musk shared a different way the Starships might dock while in orbit. In another animation, it showed the rockets connected belly to belly. Additionally, SpaceX has talked about the far future of Starship refilling and the idea of designated Starship tankers rather than normal Starship second stages. This could simplify, speed up, and increase the efficiency of the refill process. For the time being, we will have to wait and see what SpaceX ends up doing.
SpaceX’s Prior Experience
Getting two rockets to connect in orbit is no easy task but SpaceX has some experience. Through SpaceX’s commercial crew program with NASA, they have docked the Dragon capsule to the International Space Station multiple times. While this is different than two Starships, a lot of the challenge is the process of getting to the correct orbit and slowly meeting up with the other object. Things like the ISS are traveling at almost 5 miles every second. When going this fast there is no room for a mistake or miscalculation. SpaceX’s work with the ISS will likely make them a lot more confident in the future Starship refilling process.
Additional Advantage Of Reusability
Starship’s plan to be fully reusable will come in handy for the refilling process. If a non-reusable rocket wanted to dock in orbit and refill the main rocket after it was done it would fall back towards Earth and the majority of it would burn up in the atmosphere. Starship on the other hand in theory could simply reenter the atmosphere and land. Once landed SpaceX could make sure the rocket is in good condition, refill it, and repeat the process. With Starship’s goal for each launch to cost only $2 million, the act of launching a Starship just to refill another is actually not a big expense. However, in order to do this SpaceX need to ensure Starship’s costs are extremely low.
Conclusion
Starship refilling in orbit is another unique and innovative design that will help SpaceX reach its ambitious goals. The process of refilling will not only allow Starship to go further distances, but also bring even more cargo and humans along the way. SpaceX’s prior experience with the ISS will help them significantly in the process of docking a Starship to another while in orbit. Starship’s full reusability and estimated low launch cost will mean launching a Starship just to refill another would not be very expensive for the company. SpaceX has continued to do the impossible and is not slowing down on ambitious goals and ideas. We will have to wait and see if SpaceX are successful in their goal of refilling Starship while in orbit.