{"id":45237,"date":"2024-04-30T19:26:14","date_gmt":"2024-04-30T11:26:14","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/nasa-lays-out-how-spacex-will-refuel-starships-in-low-earth-orbit\/"},"modified":"2024-04-30T19:26:14","modified_gmt":"2024-04-30T11:26:14","slug":"nasa-lays-out-how-spacex-will-refuel-starships-in-low-earth-orbit","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/nasa-lays-out-how-spacex-will-refuel-starships-in-low-earth-orbit\/","title":{"rendered":"NASA lays out how SpaceX will refuel Starships in low-Earth orbit"},"content":{"rendered":"

Some time next year, NASA believes SpaceX will be ready to link two Starships in orbit for an ambitious refueling demonstration, a technical feat that will put the Moon within reach.<\/p>\n

SpaceX is under contract with NASA to supply two human-rated Starships for the first two astronaut landings on the Moon through the agency\u2019s Artemis program, which aims to return people to the lunar surface for the first time since 1972. The first of these landings, on NASA\u2019s Artemis III mission, is currently targeted for 2026, although this is widely viewed as an ambitious schedule.<\/p>\n

Last year, NASA awarded a contract to Blue Origin to develop its own human-rated Blue Moon lunar lander, giving Artemis managers two options for follow-on missions.<\/p>\n

Designers of both landers were future-minded. They designed Starship and Blue Moon for refueling in space. This means they can eventually be reused for multiple missions, and ultimately, could take advantage of propellants produced from resources on the Moon or Mars.<\/p>\n

Amit Kshatriya, who leads the \u201cMoon to Mars\u201d program within NASA\u2019s exploration division, outlined SpaceX\u2019s plan to do this in a meeting with a committee of the NASA Advisory Council on Friday. He said the Starship test program is gaining momentum, with the next test flight from SpaceX\u2019s Starbase launch site in South Texas expected by the end of May.<\/p>\n

\u201cProduction is not the issue,\u201d Kshatriya said. \u201cThey\u2019re rolling cores out. The engines are flowing into the factory. That is not the issue. The issue is it is a significant development challenge to do what they\u2019re trying to do \u2026 We have to get on top of this propellant transfer problem. It is the right problem to try and solve. We\u2019re trying to build a blueprint for deep space exploration.\u201d<\/p>\n

,<\/p>\n

Road map to refueling<\/h2>\n

Before getting to the Moon, SpaceX and Blue Origin must master the technologies and techniques required for in-space refueling. Right now, SpaceX is scheduled to attempt the first demonstration of a large-scale propellant transfer between two Starships in orbit next year.<\/p>\n

There will be at least several more Starship test flights before then. During the most recent Starship test flight in March, SpaceX conducted a cryogenic propellant transfer test between two tanks inside the vehicle. This tank-to-tank transfer of liquid oxygen was part of a demonstration supported with NASA funding. Agency officials said this demonstration would allow engineers to learn more about how the fluid behaves in a low-gravity environment.<\/p>\n

Kshatriya said that while engineers are still analyzing the results of the cryogenic transfer demonstration, the test on the March Starship flight \u201cwas successful by all accounts.\u201d<\/p>\n

\u201cThat milestone is behind them,\u201d he said Friday. Now, SpaceX will move out with more Starship test flights. The next launch will try to check off a few more capabilities SpaceX didn\u2019t demonstrate on the March test flight.<\/p>\n

These will include a precise landing of Starship\u2019s Super Heavy booster in the Gulf of Mexico, which is necessary before SpaceX tries to land the booster back at its launch pad in Texas. Another objective will likely be the restart of a single Raptor engine on Starship in flight, which SpaceX didn\u2019t accomplish on the March flight due to unexpected roll rates on the vehicle as it coasted through space. Achieving an in-orbit engine restart\u2014necessary to guide Starship toward a controlled reentry\u2014is a prerequisite for future launches into a stable higher orbit, where the ship could loiter for hours, days, or weeks to deploy satellites and attempt refueling.<\/p>\n

,<\/p>\n

In the long run, SpaceX wants to ramp up the Starship launch cadence to many daily flights from multiple launch sites. To achieve that goal, SpaceX plans to recover and rapidly reuse Starships and Super Heavy boosters, building on expertise from the partially reusable Falcon 9 rocket. Elon Musk, SpaceX\u2019s founder and CEO, is keen on reusing ships and boosters as soon as possible. Earlier this month, Musk said he is optimistic SpaceX can recover a Super Heavy booster in Texas later this year and land a Starship back in Texas sometime next year.<\/p>\n

Reuse is fundamental to Starship\u2019s long-term goal of supporting a human settlement on Mars. However, SpaceX can move forward with orbital refueling demonstrations while engineers continue experimenting with booster and ship landings.<\/p>\n

Before Starship\u2019s first landing on the Moon with astronauts, NASA\u2019s $2.9 billion Human Landing System (HLS) contract with SpaceX includes ship-to-ship propellant transfer testing and an unpiloted landing of a full-scale Starship on the lunar surface.<\/p>\n

But each Starship test flight builds on the prior mission. This means pretty much every Starship test flight over the next couple of years will have goals that feed into the first Artemis lunar landing. During these upcoming Starship test flights, engineers will measure the slosh of propellants inside the ship, along with tank pressures, and observe how the fluids respond to impulses from small thrusters. In microgravity, these small rocket jets provide \u201csettling thrust\u201d to guide the ship\u2019s liquid toward the outflow needed for refueling.<\/p>\n

Engineers will also monitor the boil-off rates of the methane and liquid oxygen in space. Over time, cryogenic liquids transition to a gaseous state without insulation or other measures to prevent boil-off. SpaceX and NASA officials want to know how much of the propellant will be lost from boil-off to know how many refueling tankers they need to launch for a Starship lunar landing mission.<\/p>\n

,<\/p>\n

\u201cAll of that needs to work properly,\u201d Kshatriya said. \u201cWe\u2019re still in development, but at a high level, I think it\u2019s important for folks to know that this sequence is underway, and they\u2019re making good engineering progress.\u201d<\/p>\n

\n

\"\"<\/p>\n

This chart presented by a senior NASA official outlines plans for SpaceX\u2019s ship-to-ship cryogenic transfer demonstration planned for 2025.<\/p>\n

Credit:
\n NASA\/Amit Kshatriya<\/p>\n<\/figure>\n

For the first full-scale refueling demonstration, SpaceX must launch two Starships within about three or four weeks of one another. First, SpaceX will launch a Starship to serve as a target vehicle in low-Earth orbit. This ship will have an augmented power system and more battery capacity to sustain itself in space long enough for the launch of the chaser vehicle\u2014a Starship that will play the role of a refueling tanker.<\/p>\n

Both ships involved in the refueling demo will also have thermal insulation and vacuum jacketing around internal plumbing to limit boil-off. \u201cOtherwise, the demo itself will not be achieved,\u201d Kshatriya said.<\/p>\n

The current plan, according to Kshatriya, is for SpaceX to use a single launch pad for both flights. By the time NASA and SpaceX are ready for a lunar landing, multiple Starship tankers will take off from at least two launch pads to aggregate propellants at a depot to supply the Moon-bound Starship. SpaceX is planning to build an additional launch tower at Starbase in Texas, and at least two Starship pads on Florida\u2019s Space Coast.<\/p>\n

This is hard, but it\u2019s doable<\/h2>\n

The two Starships will autonomously link belly to belly as they fly a couple hundred miles above the planet. On future Starship missions targeting destinations in deep space, like the Moon, this docking maneuver and refueling process will be repeated multiple times to give the vehicle enough gas to boost itself out of Earth orbit.<\/p>\n

Computer models and flight data from numerous rockets show it is possible to gain control over cryogenic boil-off, tank pressures, and propellant settling in space. But no one has ever attempted to flow cryogenic propellants from one spacecraft to another in orbit.<\/p>\n

,<\/p>\n

\u201cIn my mind, all the technical issues associated with cryo transfer in space are solved,\u201d said George Sowers, former chief scientist at SpaceX rival United Launch Alliance and a longtime proponent of depoting propellants in space. \u201cIt\u2019s just a matter of demonstrating it and fine-tuning the technology and the procedures. So, I think we\u2019re on the cusp. I\u2019m happy to see SpaceX taking the steps to make it work.<\/p>\n

Docking two Starships together won\u2019t be easy. However, SpaceX can use its experience in flying Dragon capsules to the International Space Station, which requires many of the same types of laser navigation sensors and mechanical devices necessary for Starship dockings.<\/p>\n

But there\u2019s a caveat. When Starship comes in for docking, its tanks will still be loaded with propellant, and the ship\u2019s maneuvers to approach its counterpart could induce sloshing inside the tanks. This could introduce unforeseen forces that the ship\u2019s navigation system must account for during the rendezvous.<\/p>\n

Once the two Starships come together, they will connect using the same ports SpaceX uses to load propellants on the launch pad. Then, SpaceX will fine-tune tank pressures and fire propellant settling thrusters. \u201cAt that point, they\u2019ll open up and let the propellant flow.\u201d<\/p>\n

The propellants will flow from one vehicle to the other using a pressure differential, or \u201cdelta,\u201d between the donor tank and the recipient tank. This is a simpler solution than relying on pumps.<\/p>\n

\u201cThe fundamental flow mechanism is because of the pressure delta across the umbilical,\u201d Kshatriya said.<\/p>\n

The \u201cfine details\u201d of this procedure work remain in work, he said. The slow boil-off of cryogenic propellant in the Starship refueler should raise pressures in the donor tank to help drive methane or liquid oxygen into the recipient vehicle. SpaceX can also adjust pressures using header tanks at the top of each ship.<\/p>\n

,<\/p>\n

\u201cThe trick is to get all that done, and all the transfer done, without boiling off all of your propellant in the process,\u201d Sowers said.<\/p>\n

\n

\"\"<\/p>\n

This chart includes an illustration of SpaceX\u2019s ship-to-ship refueling demonstration.<\/p>\n

Credit:
\n NASA\/SpaceX\/Amit Kshatriya<\/p>\n<\/figure>\n

The results of this refueling demonstration will allow SpaceX and NASA engineers to calculate how many refueling tankers they will need to fill up a Starship heading for the Moon. SpaceX\u2019s current estimate is approximately 10 refueling launches for one Artemis landing mission, but there are error bars on each side of this number.<\/p>\n

In its current iteration, a fully fueled Starship contains roughly 1,200 metric tons (2.6 million pounds) of propellant. SpaceX is developing larger versions of Starship to haul heavier cargo and more fuel into orbit. These upgraded Starships should reduce the number of tankers needed to load a Starship heading for the Moon or Mars.<\/p>\n

\u201cWe certainly have predictions, but we\u2019ll know how much fuel is it releasing, how long does this take, are we going to be as successful as the analysis says?\u201d said Lisa Watson-Morgan, who manages NASA\u2019s lunar landing program, in January.<\/p>\n

\u201cWe\u2019re going to have to do this a few times,\u201d she said. \u201cWe\u2019re going to have to do the prop transfer flights more than once or twice or three times in my opinion. We\u2019ve never done this before.\u201d<\/p>\n

\u201cI wish them well,\u201d said Sowers, now a professor at the Colorado School of Mines. \u201cI\u2019ve been away from ULA for almost seven years now. SpaceX used to be my competitor, and now I just want everybody to succeed. Especially, I want the whole refueling economy to get jump-started, and I\u2019m really happy that both SpaceX and Blue Origin are going down that path, as is ULA. I think for the whole world, it\u2019s finally clicked that the best way to beat the rocket equation is by refueling.\u201d<\/p>\n

Kshatriya said SpaceX\u2019s engineers are up to the task. \u201cIt\u2019s a phenomenal team, and they have exactly the right attitude in terms of how to kind of build-learn, build-learn, build-learn, and keep doing it. So I\u2019m pleased with that. I\u2019m pleased with the progress across the enterprise.<\/p>\n

\u201cA lot of folks have said it\u2019s ambitious to try this in this particular time frame. And absolutely it is.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

Some time next year, NASA believes SpaceX will be ready to link two Starships in orbit for an ambitious refueling demonstration, a technical feat that will put the Moon within reach. SpaceX is under contract with NASA to supply two human-rated Starships for the first two astronaut landings on the Moon through the agency\u2019s Artemis […]<\/p>\n","protected":false},"author":1,"featured_media":45238,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[304,6654,190,9692,316,317],"class_list":["post-45237","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-artemis","tag-artemis-iii","tag-nasa","tag-orbital-refueling","tag-spacex","tag-starship"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/45237"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=45237"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/45237\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/45238"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=45237"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=45237"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=45237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}