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#220 by obi-wan on 27 Feb, 2017 23:39
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To misquote Han Solo, "Doing a hypervelocity entry ain't like dusting crops, boy!" Entry heating rate goes like the cube of velocity...
I believe RobotBeat once said to the eighth power according to a complex formula. That's far more than cubed.
If you're talking about stagnation point heating rate that would not be correct (there are some heuristics for laminar flow that have V^3.15), but there may be some disconnect on the exact equation and parameter of interest.
Actually, in thinking about it I did remember an equation with a large exponent, so I checked my notes - there is a heuristic for stagnation point radiative hearing that has V^8.5 (Martin's formulation), whereas I was quoting convective heating. Radiative heating doesn't kick in until you get to real hypervelocity entries - at lunar return velocity, it's measurable but still dominated by convective heating. It does go up really rapidly after that, but SpaceX won't have to contend with that until they do direct entry from Mars. -
#221 by Space Ghost 1962 on 27 Feb, 2017 23:42
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My article on this all:
Good read. Especially liked the last part with Lightfoot and the WH "Landing team" heh!
https://www.nasaspaceflight.com/2017/02/spacex-two-citizens-dragon-2-lunar-mission/ -
#222 by MattMason on 27 Feb, 2017 23:47
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Fascinating. I jumped on late, expecting to find the NSF servers on fire. I'm not disappointed.
That said, my first reaction was: This was not Musk's style. He's been serious about developing tools to explore Mars. If Jeff Bezos proposed this, I wouldn't have bat one eyelash.
But I continued to read here and began thinking in the long-term. It's all about financing. Musk cannot guarantee much with NASA beyond 2024 beyond perhaps a satellite launch or two, and some comsat flights. He'll need a new revenue stream.
I wouldn't be the first to sign up, and he'd be a fool not to make a test flight, but this is certainly a 9.5 on the amazing people Pucker Factor meter.
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#223 by FutureSpaceTourist on 27 Feb, 2017 23:50
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Quote
Lori Garver @Lori_Garver 3m3 minutes ago
Lori Garver Retweeted Elon Musk
My comment to WaPost reporter: "optimistic schedule, but even doing it by 2020 would be wonderful. The plan to open new markets is working!"
https://twitter.com/Lori_Garver/status/836376848103768064 -
#224 by Chris Bergin on 27 Feb, 2017 23:51
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#225 by joek on 27 Feb, 2017 23:54
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They explicitly allow non-certified launch vehicles.
Understood. However:
- All such missions still require an FAA launch license; use of non-certified vehicles does not mean "no FAA license required".
- As there is no definition of "certification" for commercial space vehicles at this time (outside of USG CCtCap), so requiring such at this point is effectively moot.
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#226 by speedevil on 27 Feb, 2017 23:58
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<snip>
I have not worked out anything in detail - but Apollo 13s free return trajectory was at 250km altitude.
I see your point, but what science could be done? It's a free return flyby, presumably with tight payload margins. It will mostly likely be entirely automated anyway.
Lunar reconnisance orbiter is constantly orbiting a little lower than this, and has gone as low as 50km.
LRO was designed in 2006, so any instruments would be ~11 years younger, and perhaps somewhat more capable.
But - half an orbit versus continual. LRO payload was 100kg.
'Deep impact' type measurements come to mind.
Perhaps something useful could be done with a payload which separates out into multiple small impactors.
LRO does not have a spectrometer, so that impact measurements would either need to be done from existing satellites in earth orbit, earth and DSCOVR (which only has 10 band imager), or an onboard imager.
DSCOVR is very unlikely to produce much, as the resolution is too low.
Flying through the plumes of impacts is in principle possible, but 250km is quite high up, and impact velocities are quite low, meaning generation of a plume may be limited.
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#227 by punder on 27 Feb, 2017 23:59
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NASA's reacted:
https://www.nasa.gov/press-release/nasa-statement-about-spacex-private-moon-venture-announcement
I bet a lot of NASA employees are quite excited by this. But "official" NASA definitely is not. It reads almost passive-aggressive. -
#228 by montyrmanley on 27 Feb, 2017 23:59
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NASA's reacted:
https://www.nasa.gov/press-release/nasa-statement-about-spacex-private-moon-venture-announcement
It's likely that the folks at JSC and KSC are happy to hear about SpaceX's plans; the folks at Marshall and Stennis, less so.
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#229 by IanThePineapple on 28 Feb, 2017 00:00
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SpaceX COULD make a cubesat deployer to be used with Crew Dragon...
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#230 by Rocket Science on 28 Feb, 2017 00:04
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Perhaps not, but I do like their lightweight lander concept. The problem was going to an old space company and expecting a lander for a reasonable cost...
I was actually thinking that some other entity my be doing a lander, not necessarily SpaceX. Think the "Golden Spike" lander...My take is that of this flight goes well, a commercial lunar landing won't be too far behind...
Beyond that, there is a long way to go to get from there to a lunar landing which will probably require a couple of additional missions (perhaps one to go into lunar orbit and then return to Earth, and then another with an unmanned Dragon 2 landing on the lunar surface).
Consider the economics for a moment. Neither Golden Spike nor Northrup Grumman nor NASA have the budget to qualify a lander right now. Easily in the billions and decade.
The only way I can see it is to take an existing vehicle where most of that work has been done, and adapt it to the purpose.
At most there are five vehicles you can do that with on earth right now. Two are prime candidates for the role.
Golden Spike doesn't even come close ATM. Perhaps with a billion or two. Have you got that in your wallet for them , hmm? -
#231 by mme on 28 Feb, 2017 00:05
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Right, I misread your original response as a "No" to the second half of the question "would the FAA allow it." Tired brain.They explicitly allow non-certified launch vehicles.
Understood. However:
- All such missions still require an FAA launch license; use of non-certified vehicles does not mean "no FAA license required".
- As there is no definition of "certification" for commercial space vehicles at this time (outside of USG CCtCap), so requiring such at this point is effectively moot. -
#232 by punder on 28 Feb, 2017 00:06
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On the subject of comms... I can imagine a gimbaled antenna on a hinged arm, mounted inside the trunk, near the bottom. After separation from the upper stage, the arm swings out to deploy. Wonder if it will look like the CSM steerable antenna!
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#233 by Ads on 28 Feb, 2017 00:09
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So, NASA schedule vs Elon time. Which will be first to get delayed into the 2030s?
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#234 by robert_d on 28 Feb, 2017 00:09
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Could NASA offer use of the DSN and TDRSS networks, etc in return for a seat? As long as the flight is not bogged down with even more bureaucracy-addled requirements than CC? Maybe offer Jack Schmidt a slot as capcom as they slide around the moon?
Harrison "Jack" Schmitt (not Schmidt) -
#235 by DragonRider on 28 Feb, 2017 00:11
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I just can't help but think that behind the scenes Trump is playing some 4D chess here. He wants a legacy and SpaceX and/or Orion are going to give him one, probably both of them because this will give SLS/Orion a much needed kick in the pants. I just feel like in a strange way Trump will end up being the best thing to happen to Space in a long time and Elon is smart enough to stay close to him.
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#236 by matthewkantar on 28 Feb, 2017 00:11
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Space tourism is a side show. I hope these stunt persons paid full price for this. Seems to have little upside and many possible pitfalls. This make SpaceX seem less serious.
Matthew
So if a government pays for it, it's serious?
It does not matter who pays for it IMO, it is not science, it is not pushing back a frontier, providing a service like satellites, it is a joy ride/ ego trip. Looks bad if you ask me.
Matthew -
#237 by Space Ghost 1962 on 28 Feb, 2017 00:13
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Space tourism is a side show. I hope these stunt persons paid full price for this. Seems to have little upside and many possible pitfalls. This make SpaceX seem less serious.
Matthew
So if a government pays for it, it's serious?
It does not matter who pays for it IMO, it is not science, it is not pushing back a frontier, providing a service like satellites, it is a joy ride/ ego trip. Looks bad if you ask me.
And EM 1/2 ... are ... better?
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#238 by punder on 28 Feb, 2017 00:16
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Space tourism is a side show. I hope these stunt persons paid full price for this. Seems to have little upside and many possible pitfalls. This make SpaceX seem less serious.
Matthew
So if a government pays for it, it's serious?
It does not matter who pays for it IMO, it is not science, it is not pushing back a frontier, providing a service like satellites, it is a joy ride/ ego trip. Looks bad if you ask me.
Matthew
You are correct. We must stamp out all forms of joy rides and ego trips, especially when they are done by rich people using their own money.
By the way, did he really name it MoonDragon? Shouldn't he have named it Alice?
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#239 by montyrmanley on 28 Feb, 2017 00:16
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It does not matter who pays for it IMO, it is not science, it is not pushing back a frontier, providing a service like satellites, it is a joy ride/ ego trip. Looks bad if you ask me.
Matthew
Science didn't drive oceangoing vessels or railroads; commerce and adventure did. Science is not the end-all and be-all of human activity -- in fact, science is a lamprey, glomming onto a bigger fish to catch a ride. Thinking that spaceflight must *necessarily* have science is the primary goal is both limiting and silly. If science is all you want out of spaceflight, there's no reason to send people out there at all -- robots can do the job much more safely and at far less expense.
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