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billvon

Lunar program

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Been thinking about the somewhat awful plan for the return-to-the-Moon mission that NASA is working on.  The main awful thing about it is the SLS - it's a very complex, expensive expendable booster that doesn't really need to be built.  It is also the highest risk item in the program; it has never flown and will be a combination solid/liquid propellant launcher which is a more risky proposition than either one alone.  And we don't need it for any other mission.

So here's my alternative mission:

First off the ground is the SpaceX tanker.  It's a Starship/Super Heavy vehicle that has the tanker variant of the Starship on top; it's designed to hold fuel and oxidizer in orbit.  Four to eight followup flights with "standard" Starship/Super Heavy vehicles refill the tanker until it has enough fuel for a Moon expedition.

Next the lunar vehicle (the HLV) takes off.  It, again, is a modified Starship, this time with all vacuum rated engines, no thermal shielding, and everything needed for Lunar exploration (suits, equipment, supplies, everything except food and astronauts.)  It docks with the tanker and transfers fuel sufficient to get to the Moon.

So far this is identical to the NASA reference mission.  But in this case we add an ion engine to the Starship and use it for stationkeeping in orbit (saves a bit of fuel.)

Next, instead of the $20 billion SLS launch, we use a plain Falcon 9 launch to launch the astronauts aboard a Dragon.  The Dragon also contains the last consumables (food mostly) for the trip.  It docks with the HLV.  The HLV fires up its engines and heads for the moon on a free-return trajectory.  Again the ion engine is used for course correction but most of the propulsion comes from the primary methane/oxygen engines.

Once at the Moon, the HLS separates from the Dragon and lands on the Moon.  (There is some debate over whether they can use the main engines or have separate engines to avoid dust, but it's likely that the main engines will work.)  Astronauts do their thing, then return to the HLV and take off.  It rendezvous with the Dragon, and the HLV boosts the assembly back to Earth.  About halfway there the astronauts return to the Dragon, separate and make the minor adjustments needed to re-enter where they want.

Meanwhile the HLS uses its ion engine to adjust its trajectory to make an aerocapture pass; this is a very shallow re-entry that slows it down enough to get it back into Earth orbit, but not deep enough to require a thermal protection system.  Once back in orbit it again uses its ion engine to very slowly match orbit with the tanker.

Meanwhile continual flights have been refueling the tanker.  Once it docks at the tanker (which might take months) it is ready for its next mission.

This saves the entire cost of the SLS ($20 billion so far and $2 billion per launch) in favor of the HLS (which is being developed anyway) and a Falcon 9 launch ($60 million for a 'standard' flight, and it exists right now.)  And it gives you a lot more in the way of abort/rescue options - pretty much everything except the HLS itself and the falcon 9 upper stage is reusable, and having a second one standing by would be straightforward.

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2 hours ago, billvon said:

Been thinking about the somewhat awful plan for the return-to-the-Moon mission that NASA is working on.  The main awful thing about it is the SLS - it's a very complex, expensive expendable booster that doesn't really need to be built.  It is also the highest risk item in the program; it has never flown and will be a combination solid/liquid propellant launcher which is a more risky proposition than either one alone.  And we don't need it for any other mission.

So here's my alternative mission:

First off the ground is the SpaceX tanker.  It's a Starship/Super Heavy vehicle that has the tanker variant of the Starship on top; it's designed to hold fuel and oxidizer in orbit.  Four to eight followup flights with "standard" Starship/Super Heavy vehicles refill the tanker until it has enough fuel for a Moon expedition.

Next the lunar vehicle (the HLV) takes off.  It, again, is a modified Starship, this time with all vacuum rated engines, no thermal shielding, and everything needed for Lunar exploration (suits, equipment, supplies, everything except food and astronauts.)  It docks with the tanker and transfers fuel sufficient to get to the Moon.

So far this is identical to the NASA reference mission.  But in this case we add an ion engine to the Starship and use it for stationkeeping in orbit (saves a bit of fuel.)

Next, instead of the $20 billion SLS launch, we use a plain Falcon 9 launch to launch the astronauts aboard a Dragon.  The Dragon also contains the last consumables (food mostly) for the trip.  It docks with the HLV.  The HLV fires up its engines and heads for the moon on a free-return trajectory.  Again the ion engine is used for course correction but most of the propulsion comes from the primary methane/oxygen engines.

Once at the Moon, the HLS separates from the Dragon and lands on the Moon.  (There is some debate over whether they can use the main engines or have separate engines to avoid dust, but it's likely that the main engines will work.)  Astronauts do their thing, then return to the HLV and take off.  It rendezvous with the Dragon, and the HLV boosts the assembly back to Earth.  About halfway there the astronauts return to the Dragon, separate and make the minor adjustments needed to re-enter where they want.

Meanwhile the HLS uses its ion engine to adjust its trajectory to make an aerocapture pass; this is a very shallow re-entry that slows it down enough to get it back into Earth orbit, but not deep enough to require a thermal protection system.  Once back in orbit it again uses its ion engine to very slowly match orbit with the tanker.

Meanwhile continual flights have been refueling the tanker.  Once it docks at the tanker (which might take months) it is ready for its next mission.

This saves the entire cost of the SLS ($20 billion so far and $2 billion per launch) in favor of the HLS (which is being developed anyway) and a Falcon 9 launch ($60 million for a 'standard' flight, and it exists right now.)  And it gives you a lot more in the way of abort/rescue options - pretty much everything except the HLS itself and the falcon 9 upper stage is reusable, and having a second one standing by would be straightforward.

Well thought out. Thank you. But wouldn't it be cheaper, and way simpler, to just fake it?

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11 minutes ago, JoeWeber said:

Well thought out. Thank you. But wouldn't it be cheaper, and way simpler, to just fake it?

Obviously Bill cares about this planned Lunar manned mission and has given a lot of thought to it. I have also given it some thought, but my conclusions are very different. There is no good reason for a manned Moon mission at this time. Therefore in the end most likely there will not be one until there is a reason.

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Just now, gowlerk said:

Obviously Bill cares about this planned Lunar manned mission and has given a lot of thought to it. I have also given it some thought, but my conclusions are very different. There is no good reason for a manned Moon mission at this time. Therefore in the end most likely there will not be one until there is a reason.

I agree completely. We've proven beyond any doubt that using even vastly better than existing technology we won't be going anywhere soon and certainly not fast. When I suggest faking it I'm being serious. We should focus on exploring our environs virtually. Well, at least until Zuckerberg tell us where he's from and how he got here.

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2 minutes ago, gowlerk said:

I wonder what the carbon footprint for this is? What would Greta do?

Scowl is my guess. We don't need anymore American Hero's since the insurrection so screw the manned space program. Time to put money into probes, landers and deep space telescopes, I think. 

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3 hours ago, billvon said:

Been thinking about the somewhat awful plan for the return-to-the-Moon mission that NASA is working on.  The main awful thing about it is the SLS - it's a very complex, expensive expendable booster that doesn't really need to be built.  It is also the highest risk item in the program; it has never flown and will be a combination solid/liquid propellant launcher which is a more risky proposition than either one alone.  And we don't need it for any other mission.

So here's my alternative mission:

First off the ground is the SpaceX tanker.  It's a Starship/Super Heavy vehicle that has the tanker variant of the Starship on top; it's designed to hold fuel and oxidizer in orbit.  Four to eight followup flights with "standard" Starship/Super Heavy vehicles refill the tanker until it has enough fuel for a Moon expedition.

Next the lunar vehicle (the HLV) takes off.  It, again, is a modified Starship, this time with all vacuum rated engines, no thermal shielding, and everything needed for Lunar exploration (suits, equipment, supplies, everything except food and astronauts.)  It docks with the tanker and transfers fuel sufficient to get to the Moon.

So far this is identical to the NASA reference mission.  But in this case we add an ion engine to the Starship and use it for stationkeeping in orbit (saves a bit of fuel.)

Next, instead of the $20 billion SLS launch, we use a plain Falcon 9 launch to launch the astronauts aboard a Dragon.  The Dragon also contains the last consumables (food mostly) for the trip.  It docks with the HLV.  The HLV fires up its engines and heads for the moon on a free-return trajectory.  Again the ion engine is used for course correction but most of the propulsion comes from the primary methane/oxygen engines.

Once at the Moon, the HLS separates from the Dragon and lands on the Moon.  (There is some debate over whether they can use the main engines or have separate engines to avoid dust, but it's likely that the main engines will work.)  Astronauts do their thing, then return to the HLV and take off.  It rendezvous with the Dragon, and the HLV boosts the assembly back to Earth.  About halfway there the astronauts return to the Dragon, separate and make the minor adjustments needed to re-enter where they want.

Meanwhile the HLS uses its ion engine to adjust its trajectory to make an aerocapture pass; this is a very shallow re-entry that slows it down enough to get it back into Earth orbit, but not deep enough to require a thermal protection system.  Once back in orbit it again uses its ion engine to very slowly match orbit with the tanker.

Meanwhile continual flights have been refueling the tanker.  Once it docks at the tanker (which might take months) it is ready for its next mission.

This saves the entire cost of the SLS ($20 billion so far and $2 billion per launch) in favor of the HLS (which is being developed anyway) and a Falcon 9 launch ($60 million for a 'standard' flight, and it exists right now.)  And it gives you a lot more in the way of abort/rescue options - pretty much everything except the HLS itself and the falcon 9 upper stage is reusable, and having a second one standing by would be straightforward.

I would love to see SLS fly just because I never got to see a Saturn launch. It also has massive payload capacity and range but everything you say is true. It costs way too much and although it actually has an abort system (unlike the shuttles) SRBs are an unnecessary risk at this point. It probably should and will be canceled at some point. 

The spacex hardware plan sounds great but I’m not sure I’d want to rely on a modified starship to get me off the lunar surface. I think I’d still want to go old school LEM and use hypergolic engines for that.

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9 minutes ago, murps2000 said:

The spacex hardware plan sounds great but I’m not sure I’d want to rely on a modified starship to get me off the lunar surface. I think I’d still want to go old school LEM and use hypergolic engines for that.

On the other hand, the LEM had exactly one ascent engine - lose that and it's all over.  It will be nice to have two backup engines.

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2 minutes ago, billvon said:

On the other hand, the LEM had exactly one ascent engine - lose that and it's all over.  It will be nice to have two backup engines.

Bill, seriously, who shouldn't want to trade any of that for more space telescopes, probes, and autonomous landers?

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1 minute ago, JoeWeber said:

Bill, seriously, who shouldn't want to trade any of that for more space telescopes, probes, and autonomous landers?

We need geeks and dreamers too I guess. And they are all firmly in the "Man must go to Mars" camp with Elon. I'm not going to pretend I have any knowledge of the hardware these guys are excited about. It seems to me that Bill's expertise is in unmanned vehicles, so he knows their limitations. But Joe is correct, the limitations that sending humans places on what can be done mostly rule them out as cargo. We are far too fragile to waste all that launch capacity on. Not that long ago everyone was raving about Perseverance landing on Mars. It's still there plugging away. Landing on the Moon was the biggest and best adventure ever, but that was then and it has been done. Until there are realistic plans for a Moon station, what's the point?

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10 minutes ago, billvon said:

On the other hand, the LEM had exactly one ascent engine - lose that and it's all over.  It will be nice to have two backup engines.

Yes, but all they needed to do was open two valves to start it. Well, that and Buzz had to use a pen to push in a damaged circuit breaker.

Remember there’s going to be 400 or so degrees difference in temperature between the sunny and shady sides of the starship while it’s on the surface. They won’t be able to barbecue roll unless they land on a turntable. Going to be interesting to see how they manage to keep a big cryo tank of oxidizer protected in that environment during an extended lunar stay. 

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7 minutes ago, murps2000 said:

Remember there’s going to be 400 or so degrees difference in temperature between the sunny and shady sides of the starship while it’s on the surface. They won’t be able to barbecue roll unless they land on a turntable. Going to be interesting to see how they manage to keep a big cryo tank of oxidizer protected in that environment during an extended lunar stay. 

Yep.  Keep in mind that they will have fuel recondensers running on both the tanker and the HLS itself - and lunar gravity actually makes it easier to run them (no need to spin the tanks to centrifuge the fuel to where it has to go.)

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37 minutes ago, JoeWeber said:

Bill, seriously, who shouldn't want to trade any of that for more space telescopes, probes, and autonomous landers?

There's a lot we can learn with robotic probes.  There are some things we can only learn by sending people.

If we had to choose one over the other, I'd agree - robotic probes are the best return on investment.  But now we have a way to do both cheaply.  (Or will as soon as we ditch the SLS.)

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6 minutes ago, billvon said:

There's a lot we can learn with robotic probes.  There are some things we can only learn by sending people.

If we had to choose one over the other, I'd agree - robotic probes are the best return on investment.  But now we have a way to do both cheaply.  (Or will as soon as we ditch the SLS.)

I don't know, but it seems to me that whatever insight a human might offer would be seriously overwhelmed by the information obtained by other less expensive means. Mostly, we don't need new knowledge to build probes etc. We already know that if the budget is there we'll figure it out as we always have. Maybe in the next century we'll know how to send humans into space for some useful purpose. I just don't think it makes sense now.

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4 minutes ago, billvon said:

Yep.  Keep in mind that they will have fuel recondensers running on both the tanker and the HLS itself - and lunar gravity actually makes it easier to run them (no need to spin the tanks to centrifuge the fuel to where it has to go.)

Okay well there it is. I was going to say I’m sure they had to think of that. If the hull can take the stresses of the temperature difference then I guess we’re good to go. 
 

This thread seemed intended to be about the how but as usual these conversations inevitably drift toward the why. James Lovell has said in interviews that although we went to explore the moon, what we really discovered was the earth. He got to witness the first Earth rise seen by human eyes on Apollo 8. Michael Collins once remarked about how fragile the Earth looked from lunar orbit. Those are perspectives not easily attained with robotic missions. That said, I’m in agreement that if I have to choose between the two, I’d go with robotic missions over manned. I’m a huge fan of JPL. Their work and success rate speak for themselves. I can’t think of any government funded agency that has over performed the way they have.

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7 minutes ago, murps2000 said:

This thread seemed intended to be about the how but as usual these conversations inevitably drift toward the why. 

One of the "whys" for me is that we have to move industry off Earth, and this is the first (small) step.  This mission will put a fuel depot in orbit - again, a very small first step, but a step nonetheless.  In-situ resources will be next.  First for shielding bases, then for fuel, then for materials, then for food, water and oxygen.

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5 minutes ago, billvon said:

One of the "whys" for me is that we have to move industry off Earth, and this is the first (small) step.  This mission will put a fuel depot in orbit - again, a very small first step, but a step nonetheless.  In-situ resources will be next.  First for shielding bases, then for fuel, then for materials, then for food, water and oxygen.

You sound like Werner Von Braun in the late 50s. Yes, I want all of that to happen. I only hope we send actual astronauts and not just rich people.

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13 minutes ago, billvon said:

One of the "whys" for me is that we have to move industry off Earth, and this is the first (small) step.  This mission will put a fuel depot in orbit - again, a very small first step, but a step nonetheless.  In-situ resources will be next.  First for shielding bases, then for fuel, then for materials, then for food, water and oxygen.

All laudable reasons. But wouldn't proof that beings on other planets not only existed but worshiped Jesus be more valuable?

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3 minutes ago, JoeWeber said:

All laudable reasons. But wouldn't proof that beings on other planets not only existed but worshiped Jesus be more valuable?

It would but it doesn’t matter. If they don’t worship Jesus we’ll make them. Wait, I mean we’ll save them.

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1 hour ago, murps2000 said:


The spacex hardware plan sounds great but I’m not sure I’d want to rely on a modified starship to get me off the lunar surface. I think I’d still want to go old school LEM and use hypergolic engines for that.

I've always been a big believer in something like the SpinLaunch concept for repeatable moon launches. Forget any sort of chemical propellant and have a reusable, solar powered launch system up there. 

Obviously, this is way out there for a permanent moon presence though. 

 

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6 minutes ago, yoink said:

I've always been a big believer in something like the SpinLaunch concept for repeatable moon launches. Forget any sort of chemical propellant and have a reusable, solar powered launch system up there. 

Obviously, this is way out there for a permanent moon presence though. 

 

I follow a guy on YouTube named Scott Manley that talks about that. He calls it yeet launching, which is a great name. Mach 1 launches have been achieved. I bet it would work great in lunar gravity. You go first lol.

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7 hours ago, JoeWeber said:

All laudable reasons. But wouldn't proof that beings on other planets not only existed but worshiped Jesus be more valuable?

The actually worship Space Jesus.  While the location and era of his birth would suggest that Space Jesus was a little green man, modern literature depicts him as a 6'5 white dude with flowing blond hair....weird

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I'm more interested in the lunar base habitat that they should build when they arrive.

Although radiation on the moon is about half of what you get in interplanetary space, the dose is still high enough to limit stays on the surface to a few days. Not much point in going back if stays are that short.

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