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Worth noting is that because Starship HLS carries astronauts, it has to be capable of abort-to-orbit -- that is, to cancel the landing at any point and return t

Worth noting is that because Starship HLS carries astronauts, it has to be capable of abort-to-orbit -- that is, to cancel the landing at any point and return to Lunar orbit. The Apollo LEM would have done this by shutting down and dumping the descent stage then lighting the ascent motor: Starship is a single stage that should have enough fuel and oxidizer left after a successful landing to lift off and return to orbit with a minimal payload. I expect if astronauts aboard HLS lose their altimeter they'd have to abort the landing immediately -- to proceed without it would be the height of recklessness. But Odysseus had no abort-to-orbit capability so was committed to landing.

facialwipe 3y ago
I’m a huge space nerd. It takes up most of my free time. I have never once read about abort-to-orbit capability as a concept, let alone a requirement for Artemis HLS. Here’s a 4 year old video detailing past abort systems and why Starship won’t have one: https://m.youtube.com/watch?v=v6lPMFgZU5Q https://m.youtube.com/watch?v=v6lPMFgZU5Q
- Isamu 3y ago
  The video is about launch abort I believe. As opposed to aborting a lunar landing.
- dabluecaboose 3y ago
  >I have never once read about abort-to-orbit capability as a concept ATO was an abort mode [1] on the Shuttle program and is notably the only abort mode that was successfully used in the entire program, on STS-51f [2] . Challenger suffered an engine anomaly on liftoff that resulted in a lower orbit than was intended, but otherwise the mission went off without a hitch. [1] https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Abort_to_orbit https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Abor... [2] https://en.wikipedia.org/wiki/STS-51-F https://en.wikipedia.org/wiki/STS-51-F
  - mrexroad 3y ago
    Thanks! I’d seen about the bailout capability mentioned in passing, but had always wondered what it would be in practice (spoiler: a pole!). Also, I didn’t realize a second engine almost shut down on STS-51-F . Per the links: “A particularly significant enhancement was bailout capability. Unlike the ejection seat in a fighter plane, the shuttle had an inflight crew escape system[12] (ICES). The vehicle was put in a stable glide on autopilot, the hatch was blown, and the crew slid out a pole to clear the orbiter's left wing. They would then parachute to earth or the sea. […] Before the Challenger disaster, this almost happened on STS-51-F, when a single SSME failed at about T+345 seconds. […] A second SSME almost failed because of a spurious temperature reading; however, the engine shutdown was inhibited by a quick-thinking flight controller. If the second SSME had failed within about 69 seconds of the first, there would have been insufficient energy to cross the Atlantic. Without bailout capability, the entire crew would have been killed.“
    - whycome 3y ago
      > STS-51-F Why is the naming scheme of shuttle launches so bad
      - dsr_ 3y ago
        https://www.nasa.gov/missions/space-shuttle/behind-the-space-shuttle-mission-numbering-system/ https://www.nasa.gov/missions/space-shuttle/behind-the-space...
        whycome 3y ago
        Wow. It's crazier than I realized! I always wished it at least included the orbiter name in it. But I suppose the orbiter choice could change closer to actual launch. STS-41B-ATL2
      - dabluecaboose 3y ago
        It's doubly confusing that STS-51-F, with the Challenger, is the only exercised launch abort; while STS-51-L is the famous launch disaster for which Challenger is most well known.
- loa_in_ 3y ago
  Apollo Lunar Module had an abort-to-orbit that was also used to lift off the surface of the Moon after successfully completing the mission. It used explosive charges to throw the lander frame away and involved Apollo Guidance Computer manuevering into orbit at any point of the mission up until the landing.
- grouchomarx 3y ago
  the four year old video you linked to has nothing to do with aborting a landing on the moon
- MPSimmons 3y ago
  Dragon 2 has abort to orbit capabilities, too. The abort zones they call out as the rocket's IIP advances up the east coast continue until Ireland, and then after that, it's abort to orbit, where the superdracos will carry the ship to orbit without the second stage.
- lmm 3y ago
  Abort-to-orbit is a confusing term since it suggests the Shuttle's specific ATO mode. I presume the requirement is "safe abort at all points during lunar descent/landing" rather than specifically to orbit (e.g. an abort mode that put them directly on a return-to-Earth trajectory would probably also be fine).
  - rbanffy 3y ago
    Not with the LM upper stage. It’d be a couple days of recording goodbyes before they burned on reentry.
    - lmm 3y ago
      Sure. I meant more generally, presumably NASA's requirement is "has an acceptable plan to safely return them to Earth after abort" rather than specifying particular orbits.
- kqr 3y ago
  Huh, then you're one of today's lucky ten thousand! Apollo 14 had a piece of loose solder in the button triggering abort-to-orbit, so it occassionally triggered itself. This wasn't a problem en route to the moon, but the second the descent phase started it would have been a Poisson-timed bomb that would prevent the landing. There was a bit of memory that could be set to ignore the state of the abort button (this bit was the reason the abort sequence wasn't triggered en route). The problem was this ignore bit was reset by the landing sequence (to allow aborting once landing started), and they did not believe the astronauts would be quick enough to set the bit again before the button shorted out and triggered the abort. (Ignoring the abort button was fine because an abort could be triggered in the computer instead. Takes a little longer but was determined a better option than scrapping the mission.) Don Eyles came up with a clever hack. Setting the program state to 71 ("abort in progress") happened to both allow descent to start and prevented the abort button from being effective. So this program state was keyed in just before descent. The drawback was that it obviously put the computer in an invalid state so some things were not scheduled correctly but Eyles and colleages had figured out which things and the astronauts could start those processes manually. Then once the computer was in a reasonable state again the ignore abort bit could be set and the program mode set correctly and it was as if nothing had happened.
- postexitus 3y ago
  Watch "For All Mankind" - one of the huge focus areas of S1 is "abort-to-orbit" in Apollo missions. Great series in all aspects.
- dredmorbius 3y ago
  Among last-ditch options considered for the Apollo programme (specifically several planned but eliminated long-duration, two-week missions), was the ultimate LESS-is-more approach: "Lunar escape systems". This was basically a lawn-chair rocket for two which would utilise a disabled LEM's (lunar excursion module) fuel tanks, and would be hand-piloted without any guidance computer to an intercept orbit with the Apollo Command Module, with the hope that a rendezvous and crew transfer could occur within the four-hour window of space-suit oxygen supplies. Given that the CM's orbital period was two hours, this meant at best two chances for a successful intercept. <https://en.wikipedia.org/wiki/Lunar_escape_systems https://en.wikipedia.org/wiki/Lunar_escape_systems> (I'd run across this from the recently submitted MOOSE article, "Man out of space, easiest", a strap-a-foam-mattress-to-your-ass reentry concept: <https://en.wikipedia.org/wiki/MOOSE https://en.wikipedia.org/wiki/MOOSE>.)
- dotnet00 3y ago
  I think since then Elon has mentioned that abort via the main Starship engines may be possible through all points of a launch (putting aside the landing process for now). Probably also helped by the hot staging related changes, since IIRC the concern regarding abort modes was whether or not the engines could safely ignite and separate from the booster. It does still leave the system without a means of aborting if the ship's main engines have trouble, although I suppose they do have a good bit of redundancy there.
mandeepj 3y ago
> Starship is a single stage I'm no expert, so this is a question to confirm my understanding: Starship does have a booster. So, doesn't that make it a dual stage? https://www.zenger.news/2023/11/27/elon-musk-reveals-simple-reason-why-spacex-starship-uses-2-stages-instead-of-just-one-no-problem-on-mars/ https://www.zenger.news/2023/11/27/elon-musk-reveals-simple-...
- dabluecaboose 3y ago
  I think GP was saying that the lander is single-stage. By the time of a presumptive lunar landing, there's no lower stage to drop as with the Apollo LEM.
- justrealist 3y ago
  The part that's landing on the moon is just the second stage.
thereisnospork 3y ago
Assuming the landing is soft enough to survive, shouldn't it be fairly trivial for the astronauts to disembark and right the lander? To the extent anything in space is trivial. Even if it's a bit more than doable by hand a ratchet jack should make short work of it.
- jethro_tell 3y ago
  Assuming you have jack points in the right place based on the way it tipped over.
  - toss1 3y ago
    Yup, jack points in the right place, jacking equipment with sufficient range of motion, AND solid lunar soil in the right place under the jack points. Plus, you've got to get the whole jacking operation done without damaging any of your main or control thruster rockets, and without tipping past the upright point over to the other side, or just effectively rolling onto an adjacent side. I wouldn't want to go on a craft where [jacking it back upright] was in the top ten on the list of recovery options to get home.
    - rkagerer 3y ago
      All the extra mass budget would likely be better spent on a more robust attitude control system to avoid flopping over in the first place. Unless you need it for something else anyway.
    - thereisnospork 3y ago
      >I wouldn't want to go on a craft where [jacking it back upright] was in the top ten on the list of recovery options to get home. For a counter, I wouldn't want to be on a lander so fragile[0] that being manipulated upright is infeasible. Something will go wrong, maybe not on that lander, but when it does go wrong it'll have to get duct taped together. [0]Not just mechanically, but in terms of operation scope. Planning that everything must go perfectly or people die is a recipe for the latter.
narag 3y ago
I expect if astronauts aboard HLS lose their altimeter they'd have to abort the landing immediately -- to proceed without it would be the height of recklessness. In addition to the obvious, it should be taken into account that the absence of atmosphere makes very difficult to assess distance and scale. Videos of approach seem like a fractal browser.
- WalterBright 3y ago
  You can judge height by the distance to your shadow.
  - wongarsu 3y ago
    Also the rocks suddenly start rendering once you are within 500m of the surface
  - narag 3y ago
    Indeed. But only when you're close to the ground and then it could be too late.
abledon 3y ago
are they going to send a 'test run' HLS first? like, completely computer controlled, to stick the landing?
- bryanlarsen 3y ago
  Yes, that is a condition in NASA's contract with SpaceX. It is currently scheduled for 2025.
  - adonovan 3y ago
    Astronauts must be nervous stepping onto the first manned flight of a new craft that has a 100% success rate in the sole previous flight, but might have only a 50% success rate by the end of their mission...
    - eagerpace 3y ago
      I don't think nervous is the right word. It's kind of the whole thing test pilots live for.
      - fragmede 3y ago
        the word for nervous and happy is excited
    - amethyst 3y ago
      Imagine being on STS-1, piloting a shuttle that had literally never been to space before in any form. https://en.wikipedia.org/wiki/STS-1 https://en.wikipedia.org/wiki/STS-1
      - seer 3y ago
        Well at least they would have no one else to blame but themselves. As far as I remember it was the pilots that insisted on the shuttle to be not be 100% automated, so they had to do it this way. The soviets just made the whole shuttle automated so it could be tested without risk to crew.

facialwipe 3y ago

I’m a huge space nerd. It takes up most of my free time. I have never once read about abort-to-orbit capability as a concept, let alone a requirement for Artemis HLS. Here’s a 4 year old video detailing past abort systems and why Starship won’t have one: https://m.youtube.com/watch?v=v6lPMFgZU5Q https://m.youtube.com/watch?v=v6lPMFgZU5Q

Isamu 3y ago
The video is about launch abort I believe. As opposed to aborting a lunar landing.
dabluecaboose 3y ago
>I have never once read about abort-to-orbit capability as a concept ATO was an abort mode [1] on the Shuttle program and is notably the only abort mode that was successfully used in the entire program, on STS-51f [2] . Challenger suffered an engine anomaly on liftoff that resulted in a lower orbit than was intended, but otherwise the mission went off without a hitch. [1] https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Abort_to_orbit https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes#Abor... [2] https://en.wikipedia.org/wiki/STS-51-F https://en.wikipedia.org/wiki/STS-51-F
- mrexroad 3y ago
  Thanks! I’d seen about the bailout capability mentioned in passing, but had always wondered what it would be in practice (spoiler: a pole!). Also, I didn’t realize a second engine almost shut down on STS-51-F . Per the links: “A particularly significant enhancement was bailout capability. Unlike the ejection seat in a fighter plane, the shuttle had an inflight crew escape system[12] (ICES). The vehicle was put in a stable glide on autopilot, the hatch was blown, and the crew slid out a pole to clear the orbiter's left wing. They would then parachute to earth or the sea. […] Before the Challenger disaster, this almost happened on STS-51-F, when a single SSME failed at about T+345 seconds. […] A second SSME almost failed because of a spurious temperature reading; however, the engine shutdown was inhibited by a quick-thinking flight controller. If the second SSME had failed within about 69 seconds of the first, there would have been insufficient energy to cross the Atlantic. Without bailout capability, the entire crew would have been killed.“
  - whycome 3y ago
    > STS-51-F Why is the naming scheme of shuttle launches so bad
    - dsr_ 3y ago
      https://www.nasa.gov/missions/space-shuttle/behind-the-space-shuttle-mission-numbering-system/ https://www.nasa.gov/missions/space-shuttle/behind-the-space...
      - whycome 3y ago
        Wow. It's crazier than I realized! I always wished it at least included the orbiter name in it. But I suppose the orbiter choice could change closer to actual launch. STS-41B-ATL2
    - dabluecaboose 3y ago
      It's doubly confusing that STS-51-F, with the Challenger, is the only exercised launch abort; while STS-51-L is the famous launch disaster for which Challenger is most well known.
loa_in_ 3y ago
Apollo Lunar Module had an abort-to-orbit that was also used to lift off the surface of the Moon after successfully completing the mission. It used explosive charges to throw the lander frame away and involved Apollo Guidance Computer manuevering into orbit at any point of the mission up until the landing.
grouchomarx 3y ago
the four year old video you linked to has nothing to do with aborting a landing on the moon
MPSimmons 3y ago
Dragon 2 has abort to orbit capabilities, too. The abort zones they call out as the rocket's IIP advances up the east coast continue until Ireland, and then after that, it's abort to orbit, where the superdracos will carry the ship to orbit without the second stage.
lmm 3y ago
Abort-to-orbit is a confusing term since it suggests the Shuttle's specific ATO mode. I presume the requirement is "safe abort at all points during lunar descent/landing" rather than specifically to orbit (e.g. an abort mode that put them directly on a return-to-Earth trajectory would probably also be fine).
- rbanffy 3y ago
  Not with the LM upper stage. It’d be a couple days of recording goodbyes before they burned on reentry.
  - lmm 3y ago
    Sure. I meant more generally, presumably NASA's requirement is "has an acceptable plan to safely return them to Earth after abort" rather than specifying particular orbits.
kqr 3y ago
Huh, then you're one of today's lucky ten thousand! Apollo 14 had a piece of loose solder in the button triggering abort-to-orbit, so it occassionally triggered itself. This wasn't a problem en route to the moon, but the second the descent phase started it would have been a Poisson-timed bomb that would prevent the landing. There was a bit of memory that could be set to ignore the state of the abort button (this bit was the reason the abort sequence wasn't triggered en route). The problem was this ignore bit was reset by the landing sequence (to allow aborting once landing started), and they did not believe the astronauts would be quick enough to set the bit again before the button shorted out and triggered the abort. (Ignoring the abort button was fine because an abort could be triggered in the computer instead. Takes a little longer but was determined a better option than scrapping the mission.) Don Eyles came up with a clever hack. Setting the program state to 71 ("abort in progress") happened to both allow descent to start and prevented the abort button from being effective. So this program state was keyed in just before descent. The drawback was that it obviously put the computer in an invalid state so some things were not scheduled correctly but Eyles and colleages had figured out which things and the astronauts could start those processes manually. Then once the computer was in a reasonable state again the ignore abort bit could be set and the program mode set correctly and it was as if nothing had happened.
postexitus 3y ago
Watch "For All Mankind" - one of the huge focus areas of S1 is "abort-to-orbit" in Apollo missions. Great series in all aspects.
dredmorbius 3y ago
Among last-ditch options considered for the Apollo programme (specifically several planned but eliminated long-duration, two-week missions), was the ultimate LESS-is-more approach: "Lunar escape systems". This was basically a lawn-chair rocket for two which would utilise a disabled LEM's (lunar excursion module) fuel tanks, and would be hand-piloted without any guidance computer to an intercept orbit with the Apollo Command Module, with the hope that a rendezvous and crew transfer could occur within the four-hour window of space-suit oxygen supplies. Given that the CM's orbital period was two hours, this meant at best two chances for a successful intercept. <https://en.wikipedia.org/wiki/Lunar_escape_systems https://en.wikipedia.org/wiki/Lunar_escape_systems> (I'd run across this from the recently submitted MOOSE article, "Man out of space, easiest", a strap-a-foam-mattress-to-your-ass reentry concept: <https://en.wikipedia.org/wiki/MOOSE https://en.wikipedia.org/wiki/MOOSE>.)
dotnet00 3y ago
I think since then Elon has mentioned that abort via the main Starship engines may be possible through all points of a launch (putting aside the landing process for now). Probably also helped by the hot staging related changes, since IIRC the concern regarding abort modes was whether or not the engines could safely ignite and separate from the booster. It does still leave the system without a means of aborting if the ship's main engines have trouble, although I suppose they do have a good bit of redundancy there.

mandeepj 3y ago

> Starship is a single stage I'm no expert, so this is a question to confirm my understanding: Starship does have a booster. So, doesn't that make it a dual stage? https://www.zenger.news/2023/11/27/elon-musk-reveals-simple-reason-why-spacex-starship-uses-2-stages-instead-of-just-one-no-problem-on-mars/ https://www.zenger.news/2023/11/27/elon-musk-reveals-simple-...

dabluecaboose 3y ago
I think GP was saying that the lander is single-stage. By the time of a presumptive lunar landing, there's no lower stage to drop as with the Apollo LEM.
justrealist 3y ago
The part that's landing on the moon is just the second stage.

thereisnospork 3y ago

Assuming the landing is soft enough to survive, shouldn't it be fairly trivial for the astronauts to disembark and right the lander? To the extent anything in space is trivial. Even if it's a bit more than doable by hand a ratchet jack should make short work of it.

jethro_tell 3y ago
Assuming you have jack points in the right place based on the way it tipped over.
- toss1 3y ago
  Yup, jack points in the right place, jacking equipment with sufficient range of motion, AND solid lunar soil in the right place under the jack points. Plus, you've got to get the whole jacking operation done without damaging any of your main or control thruster rockets, and without tipping past the upright point over to the other side, or just effectively rolling onto an adjacent side. I wouldn't want to go on a craft where [jacking it back upright] was in the top ten on the list of recovery options to get home.
  - rkagerer 3y ago
    All the extra mass budget would likely be better spent on a more robust attitude control system to avoid flopping over in the first place. Unless you need it for something else anyway.
  - thereisnospork 3y ago
    >I wouldn't want to go on a craft where [jacking it back upright] was in the top ten on the list of recovery options to get home. For a counter, I wouldn't want to be on a lander so fragile[0] that being manipulated upright is infeasible. Something will go wrong, maybe not on that lander, but when it does go wrong it'll have to get duct taped together. [0]Not just mechanically, but in terms of operation scope. Planning that everything must go perfectly or people die is a recipe for the latter.

narag 3y ago

I expect if astronauts aboard HLS lose their altimeter they'd have to abort the landing immediately -- to proceed without it would be the height of recklessness. In addition to the obvious, it should be taken into account that the absence of atmosphere makes very difficult to assess distance and scale. Videos of approach seem like a fractal browser.

WalterBright 3y ago
You can judge height by the distance to your shadow.
- wongarsu 3y ago
  Also the rocks suddenly start rendering once you are within 500m of the surface
- narag 3y ago
  Indeed. But only when you're close to the ground and then it could be too late.

abledon 3y ago

are they going to send a 'test run' HLS first? like, completely computer controlled, to stick the landing?

bryanlarsen 3y ago
Yes, that is a condition in NASA's contract with SpaceX. It is currently scheduled for 2025.
- adonovan 3y ago
  Astronauts must be nervous stepping onto the first manned flight of a new craft that has a 100% success rate in the sole previous flight, but might have only a 50% success rate by the end of their mission...
  - eagerpace 3y ago
    I don't think nervous is the right word. It's kind of the whole thing test pilots live for.
    - fragmede 3y ago
      the word for nervous and happy is excited
  - amethyst 3y ago
    Imagine being on STS-1, piloting a shuttle that had literally never been to space before in any form. https://en.wikipedia.org/wiki/STS-1 https://en.wikipedia.org/wiki/STS-1
    - seer 3y ago
      Well at least they would have no one else to blame but themselves. As far as I remember it was the pilots that insisted on the shuttle to be not be 100% automated, so they had to do it this way. The soviets just made the whole shuttle automated so it could be tested without risk to crew.