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<\/p>\n
Starship has six Raptor engines that will power the vehicle into orbit, where it can be refueled for more Raptor burns to head for more distant destinations, like the Moon.<\/p>\n<\/figure>\n
\u201cAll the engineering disciplines, all the functional systems that you would expect, the NASA team gets insight into that and then from that we can see how their system, their design and development, how it\u2019s maturing,\u201d Watson-Morgan said. \u201cWe do provide feedback and our experience base if we see things.\u201d<\/p>\n
At least five of the booster\u2019s 33 Raptor engines failed on the first Starship test flight earlier this year. After analyzing data from that flight, engineers discovered there were fuel leaks that led to fires in the booster engine compartment. The Raptor engines, each burning methane fuel and producing about a half-million pounds of thrust, need to be a lot more reliable for SpaceX to move on to in-orbit refueling tests and Starlink launches using Starship, not to mention meeting NASA\u2019s stringent safety standards for astronauts.<\/p>\n
\u201cWe do anticipate the Raptor engines will perform better for this test,\u201d Watson-Morgan told Ars. The engines on the next Starship test flight are a mixture of first- and second-generation Raptors, whereas the first launch in April primarily used the older engine model, she said.<\/p>\n
\u201cBy the time of the Human Landing System Starship, we will be on a much later generation of Raptor, thereby having the predictability of the engines that is required for human-rating of the Starship itself,\u201d Watson-Morgan said.<\/p>\n
Everyone wants to know, but no one knows<\/h2>\n
There are a lot of unanswered questions about what it will take to send Starship to the Moon, but the basic outline of the architecture is there. SpaceX will launch a Starship depot into orbit a few hundred miles above Earth, where it will loiter to await delivery of fresh methane and liquid oxygen from a wave of Starship tankers.<\/p>\n
,<\/p>\n
The depot will have consumed its original supply of 1,200 metric tons (or more) of propellant just to get into orbit. The Starship tankers will substitute extra fuel capacity for the ability to carry 150 metric tons, or more, of cargo to low-Earth orbit, allowing each tanker to dock with the depot and gradually fill its tanks.<\/p>\n
At some point during this sequence, which will play out over the course of several weeks to several months, SpaceX will launch the human-rated lander version of Starship without anyone onboard. Once the depot is at full capacity, Starship will dock with it, receive a fresh supply of methane and liquid oxygen, then light its Raptor engines for the journey to the Moon.<\/p>\n
All of these will launch on top of the Super Heavy booster, likely alternating between launch pads in Texas and Florida.<\/p>\n
But there are a lot of unknowns. Can two Starships safely link up and connect their propellant transfer lines in orbit? The answer to this is probably yes. SpaceX has plenty of experience with this technology in docking its Dragon spaceships to the International Space Station.<\/p>\n
How much cryogenic methane and liquid oxygen will boil off in orbit? This is not as easy to know until SpaceX gathers data on the thermal behavior of these liquids, each stored hundreds of degrees below zero, after loitering for weeks to months in space. During this time, the Starship depot will be exposed to extreme temperature swings as it flies between the day and night side of Earth. Small temperature fluctuations inside the tanks can cause methane and liquid oxygen to boil off, or transition from a liquid to a gas, and be lost.<\/p>\n
How efficiently can SpaceX actually transfer propellants in microgravity? Will any propellant be lost during the transfer? Engineers need flight tests and demonstrations to know the final answer to these questions, and when those tests happen hinges on the outcome of this weekend\u2019s Starship launch.<\/p>\n
,<\/p>\n Artist\u2019s illustration of two Starships docked belly-to-belly in orbit. <\/p>\n Credit: NASA and SpaceX engineers are working together to analyze \u201cthings like ullage, for tank collapse, for slosh, for how the fluids should go from one ship to the other, the guidance navigation and control, how the two ships are going to hold steady,\u201d Watson-Morgan said. \u201cSo we are working hand in hand with them, and our experts are performing independent analysis that we\u2019re giving to SpaceX.\u201d<\/p>\n One of the next steps is a flight demonstration \u201cTipping Point\u201d technology development award SpaceX received from NASA in 2020. At that time, NASA described this $53 million award as a \u201clarge-scale flight demonstration to transfer 10 metric tons of cryogenic propellant, specifically liquid oxygen, between tanks on a Starship vehicle.\u201d<\/p>\n \u201cWe\u2019re interested in the science that comes from that, and later on next year, we anticipate a propellant transfer demonstration [between two Starships],\u201d Watson-Morgan said. \u201cThat\u2019s really when we start maturing the systems, and when it really gets exciting for HLS, because those are the building blocks that we need and, frankly, it\u2019s never been done successfully in orbit.\u201d<\/p>\n It\u2019s only after a propellant transfer demonstration that SpaceX and NASA can know the answers to some of the long-simmering questions about the Starship lander. One of those questions is the number of tanker launches SpaceX will need just to enable a single Artemis landing mission.<\/p>\n \u201cWe have a general idea, but I\u2019m reluctant to say exactly what that is because SpaceX is still designing Starship and the booster and the fleet\u2014the tankers and the depot,\u201d Watson-Morgan said. \u201cThat\u2019s why we really need, next year, the propellant transfer demonstration test because that will then help us say, \u2018OK, we see the boil-off, we see the sizing, we see how long it takes to transfer this fluid.\u2019\u201d<\/p>\n Watson-Morgan suggested the range in the number of Starship tanker flights for a single Artemis mission could be in the \u201chigh single digits to the low double digits.\u201d Elon Musk, SpaceX\u2019s founder and CEO, has suggested the company is looking at expanding Starship\u2019s capacity with larger propellant tanks. This could help reduce the number of tanker flights.<\/p>\n ,<\/p>\n Musk said in June that the switch to a \u201chot staging\u201d technique for Starship will increase the rocket\u2019s payload capacity, but Watson-Morgan said this won\u2019t affect the HLS program. \u201cWith the analysis that we see, and the predictions moving forward, the hot staging shouldn\u2019t impact for us the number of tankers or our concept of operations,\u201d she said.<\/p>\n Lakiesha Hawkins, deputy associate administrator for NASA\u2019s Moon to Mars program office, provided a different number of tanker flights Friday in a meeting of the NASA Advisory Council\u2019s human exploration and operations committee. Hawkins suggested SpaceX will need launches somewhere in the \u201chigh teens\u201d for an Artemis landing mission, with those flights lifting off from Texas and Florida about once every six days.<\/p>\n \u201cIn order to be able to meet the schedule that is required, as well as managing boil-off and so forth with the fuel, there\u2019s going to be a rapid succession of launches with fuel,\u201d Hawkins said, adding that this approach is \u201ccomplex and challenging.\u201d<\/p>\n An artist\u2019s illustration of Blue Origin\u2019s Blue Moon Mark 1 lander, a precursor to the company\u2019s human-rated lunar lander.<\/p>\n Credit: In a 2021 report, the Government Accountability Office wrote that SpaceX needed 16 launches to support a single human landing mission. Musk wrote on social media around the same time that such a high number was unlikely. He suggested a maximum of eight tanker flights to refuel a lunar-bound Starship in low-Earth orbit\u2014and possibly as few as four.<\/p>\n That doesn\u2019t appear to be a number NASA is counting on for Artemis III. \u201cIt really depends on tank stretching, tank sizes, how long they have to loiter,\u201d Watson-Morgan said.<\/p>\n The Starship depot will linger in low-Earth orbit as tankers arrive one by one. Then, once the Starship lander reaches its orbit around the Moon, it will have to wait for arrival of astronauts flying from Earth on NASA\u2019s Space Launch System rocket and Orion capsule.<\/p>\n \u201cSo there\u2019s that orchestration,\u201d Watson-Morgan said. \u201cThat\u2019s why I say it\u2019s dependent on many things, and right now we\u2019re really just focusing on getting to orbit and fully understanding the fluid dynamics associated with the prop transfer, which will be an amazing engineering feat and one that hasn\u2019t been done yet.<\/p>\n ,<\/p>\n \u201cDepending on how all that goes, then we\u2019ll determine the right steps for the uncrewed demo and move forward from there,\u201d she said. SpaceX and NASA plan to launch a Starship to the Moon for an unpiloted end-to-end demonstration before committing to use Starship for the crew lunar landing on the Artemis III mission.<\/p>\n Artemis II, scheduled to launch in late 2024 or more likely in 2025, will be the first flight of astronauts on the SLS rocket and Orion spacecraft, following a highly successful unpiloted test flight one year ago. Artemis III is officially penciled in for late 2025 on NASA\u2019s schedule, but this will undoubtedly slip, probably by multiple years.<\/p>\n Starship\u2019s readiness is one of the main factors that will determine when Artemis III flies, but there are other challenges. Axiom Space is developing new spacesuits for the astronauts to wear on the lunar surface, and the Orion spacecraft will fly with a docking port for the first time on Artemis III. Although the SLS rocket has flown before, the manufacturer of its core stage, Boeing, hasn\u2019t proved it can deliver on time.<\/p>\n \u201cYes, the lander is absolutely important. We can\u2019t go anywhere without it. But we also can\u2019t go anywhere without the suits,\u201d said Jim Free, NASA\u2019s associate administrator for exploration systems development, in Friday\u2019s advisory council meeting.<\/p>\n In May, NASA selected Blue Origin to develop a second human-rated lander. SpaceX is on contract for the Artemis III and Artemis IV landers, and Blue Origin will handle Artemis V. The companies will compete for contracts for downstream Artemis missions.<\/p>\n Blue Origin\u2019s lander concept also requires multiple launches to deliver the lander to the Moon and fill it up with propellant, although not as many as SpaceX\u2019s larger Starship vehicle.<\/p>\n It may look like this is all unnecessary given that NASA launched the Apollo lunar lander on the same Saturn V rocket as the crew-carrying Apollo command module. The next version of the SLS rocket, the \u201cBlock 1B\u201d variant planned to debut in the late 2020s, will be able to send almost as much payload to the Moon as the Saturn V.<\/p>\n ,<\/p>\n But we know the Space Launch System is expendable and expensive. A single SLS Block 1B rocket will cost at least $2.5 billion to produce, NASA\u2019s inspector recently reported. Relying on this rocket for everything would cripple NASA\u2019s space exploration program.<\/p>\n And the Apollo lunar module never stayed on the lunar surface with a crew for more than three days. On its first flight, the Starship lander will stay on the Moon for six-and-a-half days, and its endurance will grow on subsequent missions. In order to do more than repeat Apollo, NASA and its contractors need to take on new challenges.<\/p>\n Apollo 17 commander Gene Cernan drives a lunar rover, with the lunar lander visible in the background. Apollo 17 spent 75 hours on the lunar surface, the longest stay at the Moon of any human mission. Apollo 17 mission commander Eugene Cernan drives the lunar roving vehicle during the early part of the mission\u2019s first moonwalk at the Taurus-Littrow landing site. The Lunar Module is in the background.<\/p>\n Credit: \u201cThis is not Apollo 2.0,\u201d Hawkins said. \u201cWe are looking to move as quickly as we possibly can, but we are also establishing an ecosystem there on the surface of the Moon, and hence not only the more complex approach to the landing system, but all the of the elements that are supporting Artemis, to include the Gateway station, as well as the surface assets (like rovers and habitats) that we are placing on the Moon.\u201d<\/p>\n NASA\u2019s overall strategy remains pointed toward sending people to Mars. The Moon missions are an appetizer, offering a chance for practice and technology development in Earth\u2019s neighborhood. NASA recently completed an architecture review for future human exploration of Mars, but those plans are even murkier than the details for getting Starship to the Moon.<\/p>\n Nevertheless, NASA sees the Artemis lunar missions, while historic and challenging on their own, as just a stepping stone. A human mission to Mars will likely need things like in-space refueling, propellant depots, and advanced propulsion and life support. Those are all part of Artemis.<\/p>\n \u201cWe\u2019re definitely trying not to be shortsighted about this,\u201d Hawkins said.<\/p>\n","protected":false},"excerpt":{"rendered":" NASA managers are in South Texas this weekend as SpaceX prepares to launch its second full-sized Starship rocket. If the rocket flies perfectly, it will unlock additional tests beginning as soon as next year to prove that SpaceX can transfer hundreds of tons of super-chilled methane and liquid oxygen between two spaceships in orbit. This […]<\/p>\n","protected":false},"author":1,"featured_media":45706,"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":[],"class_list":["post-45703","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/45703"}],"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=45703"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/45703\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media\/45706"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=45703"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=45703"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=45703"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2023\/11\/starships-docked-1.jpg\")
<\/p>\n
\n SpaceX<\/p>\n<\/figure>\n\u201cComplex and challenging\u201d<\/h2>\n
![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2023\/10\/bluemoonmk1art.jpg\")
<\/p>\n
\n Blue Origin<\/p>\n<\/figure>\nNot Apollo 2.0<\/h2>\n
![\"\"](\"https:\/\/cdn.arstechnica.net\/wp-content\/uploads\/2023\/11\/eugene_cernan-full-a.jpg\")
<\/p>\n
\n NASA\/Harrison Schmitt<\/p>\n<\/figure>\n