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#640
by
Negan
on 02 Mar, 2017 15:05
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Didn't Musk already say this would be the first Dragon to go beyond LEO?
Edit: He certainly feels the heat shield is already up to the task of lunar return. How many times has a heat shield failed (other than Columbia which was for a very specific reason.)? This whole must do a full on free return test is FUD.
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#641
by
rakaydos
on 02 Mar, 2017 15:09
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The key point seems to be to me at least. There are no longer wires going from a switch to an engine. The whole thing is hooked up to a computer. As long as the computer works, a human has nothing to do. When it does not work, there is nothing a human can do.
Except I remember from the early days that entry is passively stable. So once you are on a survivable reentry path you can do with complete computer failure. The parachutes can be manually activated in that situation.
Your statement says "once your one a survivable path", at what point in a BEO reentry with computer failure are you on a survivable path? 
If you watch the NASA Apollo era video that was posted on page 8 (reply 158) of this thread, you will see how the BEO reentry is controlled by the computer. Small-ish errors in the reentry corridor angle which may or may not be discernible by a human pilot with no computer will most likely result in excessive g/structural/thermal loads (too steep) or skipping off the atmosphere (too shallow). Also the steering (pitch/yaw/roll) done by the computer provides the necessary/correct cross-range for landing accuracy. The human pilot could not carry that task out with a high level of reliability.
Personally I am very excited for this crewed proposal, but I will not argue for the case of having the humans in the loop to provide BEO reentry back up. Its kind of like that argument about having the Falcon 9 landing being dynamically controlled with feedback from the ASDS in real-time vs. the autonomous way it is actually done.
Something I dont understand is what is wrong with skipping off? Sure, in Apollo they had to discrd their life support equipment and power supply, and thus could not survive "going around for another pass", but Dragon for the most part doesnt have that problem with the Trunk.
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#642
by
Lee Jay
on 02 Mar, 2017 15:12
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I've been sick and out-of-the-loop the last couple of days, but reading this made me a bit depressed.
So I went back and started reading the thread from the beginning.
Looks like I'm not the only one, but pretty darned close.
The more I see of this sort of thing the more disenfranchised I feel about where spaceflight is actually heading versus where I'd like it to be heading.
Sure, I'll watch the mission carefully, and even be excited doing so (I'm a techno-geek), but this sort of thing - and SpaceX's Mars plans in general - are not where I'd like us to be going in spaceflight, especially human spaceflight.
In a way, I completely agree, and then in another way, disagree....
If there was no context to this, and all you'd be telling me is about a company that built the minimal infrastructure required to fly around the moon, for tourism purposes, I'd be with you - puke. Neil Armstrong, for this?!
But there is context. This is a company focused on the real thing - beyond exploration even - actually forming a spacefaring civilization. Sacred words, pretty much, straight out of childhood's sci-fi.
I don't like their Mars plans either. They're focued on colinization which is folly and about the fifteenth major step in a human Mars program. We're on about step three.
You think he hasnt thought about steps four through fourteen?
Thought about, maybe, but without plans to implement.
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#643
by
rsdavis9
on 02 Mar, 2017 15:12
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The key point seems to be to me at least. There are no longer wires going from a switch to an engine. The whole thing is hooked up to a computer. As long as the computer works, a human has nothing to do. When it does not work, there is nothing a human can do.
Except I remember from the early days that entry is passively stable. So once you are on a survivable reentry path you can do with complete computer failure. The parachutes can be manually activated in that situation.
Your statement says "once your one a survivable path", at what point in a BEO reentry with computer failure are you on a survivable path?
If you watch the NASA Apollo era video that was posted on page 8 (reply 158) of this thread, you will see how the BEO reentry is controlled by the computer. Small-ish errors in the reentry corridor angle which may or may not be discernible by a human pilot with no computer will most likely result in excessive g/structural/thermal loads (too steep) or skipping off the atmosphere (too shallow). Also the steering (pitch/yaw/roll) done by the computer provides the necessary/correct cross-range for landing accuracy. The human pilot could not carry that task out with a high level of reliability.
Personally I am very excited for this crewed proposal, but I will not argue for the case of having the humans in the loop to provide BEO reentry back up. Its kind of like that argument about having the Falcon 9 landing being dynamically controlled with feedback from the ASDS in real-time vs. the autonomous way it is actually done.
Something I dont understand is what is wrong with skipping off? Sure, in Apollo they had to discrd their life support equipment and power supply, and thus could not survive "going around for another pass", but Dragon for the most part doesnt have that problem with the Trunk.
trunk has solar power?
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#644
by
envy887
on 02 Mar, 2017 15:12
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The key point seems to be to me at least. There are no longer wires going from a switch to an engine. The whole thing is hooked up to a computer. As long as the computer works, a human has nothing to do. When it does not work, there is nothing a human can do.
Except I remember from the early days that entry is passively stable. So once you are on a survivable reentry path you can do with complete computer failure. The parachutes can be manually activated in that situation.
Your statement says "once your one a survivable path", at what point in a BEO reentry with computer failure are you on a survivable path?
If you watch the NASA Apollo era video that was posted on page 8 (reply 158) of this thread, you will see how the BEO reentry is controlled by the computer. Small-ish errors in the reentry corridor angle which may or may not be discernible by a human pilot with no computer will most likely result in excessive g/structural/thermal loads (too steep) or skipping off the atmosphere (too shallow). Also the steering (pitch/yaw/roll) done by the computer provides the necessary/correct cross-range for landing accuracy. The human pilot could not carry that task out with a high level of reliability.
Personally I am very excited for this crewed proposal, but I will not argue for the case of having the humans in the loop to provide BEO reentry back up. Its kind of like that argument about having the Falcon 9 landing being dynamically controlled with feedback from the ASDS in real-time vs. the autonomous way it is actually done.
Something I dont understand is what is wrong with skipping off? Sure, in Apollo they had to discrd their life support equipment and power supply, and thus could not survive "going around for another pass", but Dragon for the most part doesnt have that problem with the Trunk.
Dragon needs the trunk for power and cooling. It can't survive very long without it, although I haven't seen a number for exactly how long.
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#645
by
meekGee
on 02 Mar, 2017 15:17
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I've been sick and out-of-the-loop the last couple of days, but reading this made me a bit depressed.
So I went back and started reading the thread from the beginning.
Looks like I'm not the only one, but pretty darned close.
The more I see of this sort of thing the more disenfranchised I feel about where spaceflight is actually heading versus where I'd like it to be heading.
Sure, I'll watch the mission carefully, and even be excited doing so (I'm a techno-geek), but this sort of thing - and SpaceX's Mars plans in general - are not where I'd like us to be going in spaceflight, especially human spaceflight.
In a way, I completely agree, and then in another way, disagree....
If there was no context to this, and all you'd be telling me is about a company that built the minimal infrastructure required to fly around the moon, for tourism purposes, I'd be with you - puke. Neil Armstrong, for this?!
But there is context. This is a company focused on the real thing - beyond exploration even - actually forming a spacefaring civilization. Sacred words, pretty much, straight out of childhood's sci-fi.
I don't like their Mars plans either. They're focued on colinization which is folly and about the fifteenth major step in a human Mars program. We're on about step three.
So you don't like the Mars plan since it is too far-reaching, and you don't like this plan since it is too near sighted.
Hard man to please.
What is it that you want them to aim at?
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#646
by
RoboGoofers
on 02 Mar, 2017 15:21
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The important thing is that the computers don't go down. Without them you don't get home. There are no manual controls on Dragon unlike Mercury. All control inputs go though computers.
There are a few other critical systems for navigation, particularly star trackers and the IMU, (also, of course, communications.) The technology for these things has come on a lot since Apollo. And you would expect a lot of redundancy in these systems.
There is nothing for the crew to do on this flight as far as navigation is concerned. The spacecraft can do a lot of it autonomously along with ground command. The crew might have the option of choosing the attitude to get a better view during the flight, but that would have nothing to do with navigation.
I doubt they'll even have that. There's only the moon and earth too look at. SpaceX mission planners will have all the maneuvers for the best views planned out ahead of time.
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#647
by
Ben the Space Brit
on 02 Mar, 2017 15:22
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trunk has solar power?
My understanding was that the Dragon Mk2 trunk was a very minimalist affair and that the spacecraft itself was considered to have sufficient battery power for the entire of an ISS crew rotation + margin. If that is still the plan, then this mission
will use a non-stock trunk.
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#648
by
mme
on 02 Mar, 2017 15:23
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I think the solution to the problem is to just accept that Dragon launches don't count toward AF acceptance.
That's not really a "solution" for the topic of this thread if you consider the limited number of flights FH can realistically have by the time the end-of-2018 timeframe comes. People didn't start invoking Dragon on the FH demo for no particular reason, but as a means to make that schedule somewhat more realistic.
Some things to consider:
...
All of this combined suggests the number of FHs launched in the next 2 years will be low, even if we assume no major snags during the inaugural campaign. This leaves very few opportunities to test a Dragon 2 with a BEO-like reentry velocity. As for the recent comments about increased production rate later this year, we've heard it all before. Seeing is believing.
We're talking across each other. I am not opposed to using Dragon on the demo flight. I'm opposed to creating special PF to add an unnecessary fairing around the Dragon in the hope that the AF would still count the demo as a qualification flight. More mass, more separation events, more complexity and may not even qualify in the AF's eyes since it's not the PF they'd use. My "solution" is prioritizing what is more urgent and if Dragon is more urgent than a flight that counts toward AF acceptance, so be it.
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#649
by
jpo234
on 02 Mar, 2017 15:26
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Falcon 9 Block 5 can almost certainly launch Dragon 2 around the Moon if it doesn't need to carry any payload and they are willing to throw the booster away. No need for FH for Dragon test flights.
But this would significantly increase the price tag of the moon cruise, wouldn't it?
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#650
by
Comga
on 02 Mar, 2017 15:29
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Wow. I can't remember hearing so much whining in a thread in a long time in NSF. Two people are going to PAY SpaceX for a trip around the Moon!
"Waah! It's shouldn't be rich people! It should be someone from Category X that I like better and paid for by someone else!" "Waah! They can't do it without a professional astronaut!" Waah! They're just tourists!" "Waah! It's too dangerous! Let's sneer at it and maybe it'll go away!"
I wonder if the same thing happened on, say, oceanographic forums condemning Cameron for going to the bottom of the Marianas Trench as a TOURIST? Probably did, if the same kind of people are on there. Or let's pile on anyone who pays a bunch of money to jump out of a balloon in the Stratosphere: "Waah! That should only be done by professional test pilots!".
What is the matter here? It's their money, not yours. Someone is helping push BEO flight along and some of you are acting like they are killing babies or something.
I'd go in a heartbeat. Crowdfunding, anybody?
Bravo!
All this fussing. Let's apply "Dog Rules" as in "Why does a dog lick his..... parts? Because he can."
Once Falcon Heavy is demonstrated, and SpaceX is ready, or has flow, a passenger mission (The term "crewed" is so clumsy.) to the ISS, there isn't that much else required for a Zond/Apollo 13 circumlunar mission.
A couple of wealthy and adventurous people talking to Space Adventures approach SpaceX with enough money to make it worthwhile. (2*${50+?}M?). What is Musk going to say? No?
He informs NASA. (I know second hand that the mission plan was know a week ahead of time.) NASA puts on a show of their own. Lots of people there and their supporters aren't happy. (They won't be happy when China gets to the Moon while we are still doing PowerPoints about our #JourneyToMars, but they will face that when it comes.) Everyone draws smiley faces.
People scoff at SpaceX's schedule. It slips. Endless debates ensue about what to call the "fliers". They debate if circumlunar is reall BEO or just BLEO. People post "better" mission designs. People assume that SpaceX is careless, or hasn't thought of obvious issues. They want their preferred type of people to fly, preferably a random choice where they have P=10^-7 chance to go instead of zero. Cry me a river.
Other talk about EVAs and SEVAs and telescopes and surface probes, lunar satellites, companion satellites. All way more than what's available and likely. They say the passengers will be bored. That it's a one-off and no one will care after the first. Simonyi went to the ISS TWICE. I personally know people who have been to the summit of Everest multiple times. These experiences are not just for bragging rights. Anything this big is an incomparable adventure and will generate a lineup of applicants, even if it involves sitting in a can for a week.
This is great. It's a flight beyond LEO. It is an adventure and a spectacle. I wish them all well.
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#651
by
douglas100
on 02 Mar, 2017 15:32
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#652
by
manoweb
on 02 Mar, 2017 15:33
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Personal considerations: not only I think the Moon is the first logical step, but I actually do not care about the Mars plans too much. If I were a billionaire I would totally apply for the Moon tour (and maybe a landing later on) but I would not care to relocate to Mars, at all. And, I think the Moon trips are very good: the end of setting up a reliable, routing space access for civilians with *no training* (think of the process of flying on a commercial airliner, possibly without TSA, where the only training is the hostess boringly giving you the safety instructions before takeoff) is the most important thing human kind can do.
So for this trip, I hope the participants won't have to go through more than a few days of training, and that they won't be forced to conduct lame science experiments on board unless they like to perform the usual tricks with water bubbles etc. I wonder what kind of food they will eat, just freeze dried stuff or they will have some sort of oven to hat up real meals? Will they be allowed to carry any nice bottle (or pouch) of wine to celebrate? Will they have to wear the spacesuit at all times or only for takeoff and landing? What kind of internet bandwidth will they have, and will they bring their own devices (phones, tablets, laptops) or they will have to use the Dragon screens for that? It's funny to think that Dragon would provide wi-fi access. If so, what kind of network will they use? To me these are important questions, and the fact that in the next several months we might have answers, is so exciting.
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#653
by
manoweb
on 02 Mar, 2017 15:42
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These are in fact technical questions, not personal considerations:
- will this orbit be just an elliptical Earth Orbit that is big enough that it crosses the Moon's path? Or the Moon plays a fundamental role in the trajectory? (I have seen a drawing of the trajectory that looks like an "8" loop)
- would it be possible to make the mission go back and forth Earth and Moon multiple times (assuming the Astronauts had enough food/water etc) or this option requires a different launch profile? (I think that the Moon orbiting around Earth, so changing relative position, will be a challenge, but I cannot quantify if there might be ways to compensate)
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#654
by
envy887
on 02 Mar, 2017 15:43
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Falcon 9 Block 5 can almost certainly launch Dragon 2 around the Moon if it doesn't need to carry any payload and they are willing to throw the booster away. No need for FH for Dragon test flights.
But this would significantly increase the price tag of the moon cruise, wouldn't it?
It would be a test flight. No people on board. I don't think it would be a great idea, especially if a reuseable FH can get a better test flight; but it's a possible option.
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#655
by
jpo234
on 02 Mar, 2017 15:46
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These are in fact technical questions, not personal considerations:
- will this orbit be just an elliptical Earth Orbit that is big enough that it crosses the Moon's path? Or the Moon plays a fundamental role in the trajectory? (I have seen a drawing of the trajectory that looks like an "8" loop)
- would it be possible to make the mission go back and forth Earth and Moon multiple times (assuming the Astronauts had enough food/water etc) or this option requires a different launch profile? (I think that the Moon orbiting around Earth, so changing relative position, will be a challenge, but I cannot quantify if there might be ways to compensate)
It will probably look like this (
Credit: Circumlunar Free Return Trajectory by Robert A. Braeunig):
Edit: Make sure the simulation is properly credited.
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#656
by
Danderman
on 02 Mar, 2017 15:47
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That trimmed portion is really, truly not relevant. It can be summarized as: SpaceX found that launching a Falcon Heavy is a bit more complicated than just strapping boosters together, which combined with the lack of reason to prioritize it (few launches, and other priorities) has led to it being pushed back a few years, with unrelated issues (launch failures) being major drivers of the most recent delays.
Let me prequote you from a few years from now:
"SpaceX found that flying beyond Earth orbit" was a bit more complicated than just pushing an object deeper into space".
Note that I am not saying that SpaceX won't do all sorts of great things in the future (fingers crossed), I am saying that this particular announcement is not likely to result in a flown mission anywhere close to 2018, or that the mission as announced is likely to morph into something else as time passes.
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#657
by
ThereIWas3
on 02 Mar, 2017 15:55
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Something I dont understand is what is wrong with skipping off?
Because after skipping off, when you come back down (
if you come back down at all) it will be somewhere you did not plan for and there will be no recovery ship. Might even be some nasty place. And you might come in too steep the second time and burn up.
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#658
by
bad_astra
on 02 Mar, 2017 16:09
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Yes - an EVA of any kind on a mission such as this is a complete non-starter, a non-issue. And just reiterating for the nth time, for those who didn't see earlier posts - James Cameron absolutely is not involved in any space missions for the forseeable future - he's making 'Avatar' sequels for the next few years.
But a filmaker going up there would definitely be able to recoup some of the cost of the journey, if not recouping it. 10 days of weightless flight, close shots of the moon. The public interest. It would add up.
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#659
by
FutureSpaceTourist
on 02 Mar, 2017 16:11
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Didn't Musk already say this would be the first Dragon to go beyond LEO?
Does anyone have a source for this? I'd be very nervous about sending people - especially paying customers - beyond LEO if SpaceX hasn't done it before. Surely they have to test beyond LEO that their navigation, tracking, comms, maybe radiation effects etc are all ok first?
Edit: typo
