Author Topic: Fast transits and aerocapture  (Read 6609 times)

Online Pipcard

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Fast transits and aerocapture
« on: 10/24/2016 03:16 AM »
So the main aim of the fast transit for the interplanetary spaceship (80-150 days depending on the launch window) is to enable more frequent reuse (i.e. within the 26-month Earth-Mars synodic period).

But do we know about whether the PICA-X can withstand the higher entry velocities that have to be deeper into the relatively thin atmosphere in order for aerocapture to happen, if it even is possible? As in, is it possible to be aerocaptured without the periapsis of the hyperbolic orbit being below the surface? The cylindrical lifting body shape helps with surface area and tries to prevent a ballistic collision course, but will it be enough, especially when braking heavy cargo (due to the square-cube law)? And what about the g-forces that will be experienced by passengers when it needs to reduce a lot of velocity in a short period of time?

Using current propulsion technologies, and aerocapture technologies, You are looking at 6 months transit time either way. If you went any faster (which you could, just launch a bigger EDS with bigger tanks on a bigger rocket), you'd get to Mars going so fast, that you couldn't aerocapture, and would bounce off and fly off into deep space.  That would make for a bad day.  So 6 months is about as fast as you can get there without a breakthrough tech like VASIMR (I'll touch on that in a moment).
« Last Edit: 10/24/2016 03:59 AM by Pipcard »

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #1 on: 10/24/2016 04:15 AM »
So the main aim of the fast transit for the interplanetary spaceship (80-150 days depending on the launch window) is to enable more frequent reuse (i.e. within the 26-month Earth-Mars synodic period).

But do we know about whether the PICA-X can withstand the higher entry velocities that have to be deeper into the relatively thin atmosphere in order for aerocapture to happen, if it even is possible? As in, is it possible to be aerocaptured without the periapsis of the hyperbolic orbit being below the surface? The cylindrical lifting body shape helps with surface area and tries to prevent a ballistic collision course, but will it be enough, especially when braking heavy cargo (due to the square-cube law)? And what about the g-forces that will be experienced by passengers when it needs to reduce a lot of velocity in a short period of time?

You can safely assume they have calculated the entry stresses. The pressurized area is huge, so the density is not too high even with a lot of cargo. They may not send 450t on the first flights and gain some experience first.

Offline Impaler

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Re: Fast transits and aerocapture
« Reply #2 on: 10/24/2016 05:52 AM »
The outbound speed is not what makes or breaks a 1 synod cycle, it's the return trajectory which has to be some kind of opposition return rather then the much easier conjunction return.  Also vehicle entry heating will be worst at Earth not mars.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #3 on: 10/24/2016 09:31 AM »
The outbound speed is not what makes or breaks a 1 synod cycle, it's the return trajectory which has to be some kind of opposition return rather then the much easier conjunction return.  Also vehicle entry heating will be worst at Earth not mars.

Yes, they could test it before going to Mars. Do a loop around the moon and use more fuel to accelerate toward reentry. They could match interplanetary reentry speed that way.

Edit: assuming the first returning BFS will carry a crew they will probably want to really test earth reentry at full speed.
« Last Edit: 10/24/2016 09:32 AM by guckyfan »

Offline Shuggy

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Re: Fast transits and aerocapture
« Reply #4 on: 10/24/2016 10:09 AM »
I will admit to not being an expert in this at all, but I did have another thought on the Pica X heatshield, which is sort of relevant here.  It's all very well that it can be reused potentially a number of times and deal with faster re-entries, but does this factor in sitting in the Mars Atmosphere for many months with no protection from dust, UV and radiation?  I guess it will have to, as its rather a large area for trying to cover once landed, not impossible I suppose.

I'd be nervous about re-entry on any heat shield (earth is fine for me!), but a heat shield that has sat on Mars for a year exposed to the elements would make me a lot more nervous!  Especially doing an even faster entry than normal.

Online biosehnsucht

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Re: Fast transits and aerocapture
« Reply #5 on: 10/24/2016 04:58 PM »
Unlike Dragon / Crew Dragon, where it has to withstand the potentially higher UV and radiation environment of LEO, and the dust on Mars (when sitting on the surface) isn't anything like MMOD ... pretty sure these aren't the issues to worry about.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #6 on: 10/24/2016 05:08 PM »
They may need to come up with something on earth. It was said PicaX does not like water. So what if it is exposed to rain? A little rain before launch? Potentially a lot of rain when standing outside. The Drago heatshield would be protected. They may need hangars.

Offline Arb

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Re: Fast transits and aerocapture
« Reply #7 on: 10/24/2016 05:55 PM »
It was said PicaX does not like water.
?
Citation needed.

Offline Radical_Ignorant

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Re: Fast transits and aerocapture
« Reply #8 on: 10/24/2016 10:45 PM »
Hi, sorry I'm on darn mobile and can't quote. This is question to opinion from first post that fast transit is to maximize reuse.

Does that mean that SpaceX plans to send ship to Mars, unload and fuel it in short time and then send it fast back to Earth so the very same ship can go to Mars again in  next two years?
If that's the case can someone please point me to source of this info?

I was reading today Zurbin's critique about ITS and have some doubts about his opinion. Firstly he assumes that ITS second stage cant be additionally resupplied in higher orbit if additional fuel would provide enough benefit.
Secondly why ITS upper stage can't be send back to Earth shortly after landing and therefore be fully reused every two years. He said that slower six month transit allows return trip. So why not send back ship if it's there earlier an use it again in two years?

I only fully agree with his doubts about spaceX being able to pull it of financially. But if there is anyone who could get funds for this it's Elon.
« Last Edit: 10/24/2016 10:49 PM by Radical_Ignorant »

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #9 on: 10/25/2016 10:02 AM »
It was said PicaX does not like water.
?
Citation needed.

I have heard it during early splashdowns of cargo Dragons. It may be true only with salt water. PicaX is very lightweight. Saline water might penetrate and the salts remain when it dries. In that case some rain would not be a problem.

I am sure the designers of BFS have not missed such a problem if it does exist.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #10 on: 10/25/2016 10:15 AM »
This is question to opinion from first post that fast transit is to maximize reuse.

Does that mean that SpaceX plans to send ship to Mars, unload and fuel it in short time and then send it fast back to Earth so the very same ship can go to Mars again in  next two years?
If that's the case can someone please point me to source of this info?

Elon Musk has said it on many presentations. It is at the center of his message, how to get cost down. Reuse and reuse often.

Offline Radical_Ignorant

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Re: Fast transits and aerocapture
« Reply #11 on: 10/27/2016 11:59 PM »
Wow - How I could lost that? Hearing what I because of some unknown reason was expected to hear. I was because of some very obscure reason shure that it's one way trip per alignment. So BFS is shoot to Mars, then two years later it's soot bac to Earth, then next two years later it's shoot agai to Mars.
Thanks for clarification. That's big difference. So BFS will be in use rougly 1/3rd of the time (4 months * 2 ways) per every 26 months. That's something. Much more use of them than of a private a car for example.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #12 on: 10/28/2016 07:54 AM »
Wow - How I could lost that? Hearing what I because of some unknown reason was expected to hear. I was because of some very obscure reason shure that it's one way trip per alignment. So BFS is shoot to Mars, then two years later it's soot bac to Earth, then next two years later it's shoot agai to Mars.
Thanks for clarification. That's big difference. So BFS will be in use rougly 1/3rd of the time (4 months * 2 ways) per every 26 months. That's something. Much more use of them than of a private a car for example.

Right. Except that the data given in Elons IAC conference point in another direction. It seems to me that sending 300 or 450t slow and reuse only every 4 years beats sending 150t and reuse every 2 years. Not the least advantage would be that the fuel production on Mars for cargo would be cut in half.

Passengers would be different. Going slow will not increase number of people, but would increase radiation and microgravity exposure. So going fast with passengers might be better and cheaper due to frequent reuse.

Offline Robotbeat

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Re: Fast transits and aerocapture
« Reply #13 on: 10/28/2016 02:37 PM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

By the way, Musk mentioned orbital transfer to get to 450 tons. This suggests we have not seen the full breadth of the ITS architecture space. There may be use modes which we have not assumed but which SpaceX are looking at.
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Offline Impaler

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Re: Fast transits and aerocapture
« Reply #14 on: 10/29/2016 03:40 AM »
Wow - How I could lost that? Hearing what I because of some unknown reason was expected to hear. I was because of some very obscure reason shure that it's one way trip per alignment. So BFS is shoot to Mars, then two years later it's soot bac to Earth, then next two years later it's shoot agai to Mars.
Thanks for clarification. That's big difference. So BFS will be in use rougly 1/3rd of the time (4 months * 2 ways) per every 26 months. That's something. Much more use of them than of a private a car for example.

Right. Except that the data given in Elons IAC conference point in another direction. It seems to me that sending 300 or 450t slow and reuse only every 4 years beats sending 150t and reuse every 2 years. Not the least advantage would be that the fuel production on Mars for cargo would be cut in half.

Passengers would be different. Going slow will not increase number of people, but would increase radiation and microgravity exposure. So going fast with passengers might be better and cheaper due to frequent reuse.

Their is a great irony involved in mars return trajectories, a trajectory that allows the vehicle to make one round trip every synod will involve a VERY long duration is space or nearly 1.3 years for the return leg.  This is clearly unacceptable for human flight being longer then any human has ever spent in space in one stretch and that was in LEO which is far milder.

While a trajectory that would have the vehicle making a round trip every 2 synods, aka half the amortization, would involve a return trajectory of a few months much like the outbound leg.

The propellant needs for return would NOT be very different between these options and as both make use of the same outbound trajectory they have no effect on cargo delivery, it is just a matter of when you depart from mars, the first trajectory involves a much shorter stay on mars, the other involves staying on mars for about an additional year.  The result is that the total time away from Earth being very similar for both options so again no significant effect on consumables either.

While mars surface has dangers and health risks it is considerably better then being in interplanetary space on a 1 to 1 time basis, so making 2 fast transits and staying a long time on the surface is the safest option and it provides the best use of time for exploration and the activities which people have been sent for in the first place.

Musk's plan for 1 synod cycles is simply not tenable and will have to be dropped in favor of a slower cycle.

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Re: Fast transits and aerocapture
« Reply #15 on: 10/29/2016 04:04 AM »
Since there's likely to be more cargo flights than passenger flights for some time yet, sending cargo flights back on the same synod (increasing their amortization) seems fine since they'll be basically empty of life. This also decreases the number of needed cargo BFS since you'll get them back faster.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #16 on: 10/29/2016 06:09 AM »
Since there's likely to be more cargo flights than passenger flights for some time yet, sending cargo flights back on the same synod (increasing their amortization) seems fine since they'll be basically empty of life. This also decreases the number of needed cargo BFS since you'll get them back faster.

If they can send twice as much cargo in a two synod flight it is more efficient than fast transfer. For crew, I don't know wether they can speed up one synod transfer earth return with sufficient fuel. I have always hoped they will find all necessary materials for fuel ISRU on Phobos or Deimos and do in orbit refuelling. It would give huge margins for fast flights.

When transfering many people to Mars in many ships and few back they could do both. Send most crew ships back empty in one synod and send one later and on a fast trajectory with people.
« Last Edit: 10/29/2016 06:18 AM by guckyfan »

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #17 on: 10/29/2016 06:17 AM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

Where would you see those other refuelling positions?

By the way, Musk mentioned orbital transfer to get to 450 tons. This suggests we have not seen the full breadth of the ITS architecture space. There may be use modes which we have not assumed but which SpaceX are looking at.

It sounded like a possible option they have not thought through very much yet.

There are sure possible and useful extensions to the architecture. A vehicle for cislunar space. A dedicated  cargo version, though I am not sure one is needed except some internal modifications of the pressurized area. A tanker with a much smaller outer mould line and slightly higher capacity. Assuming that the tanker has separate tanks for its fuel cargo, a version that has only one larger tank. That would open a lot of options for other missions and other mission profiles. What Elon Musk has presented is the minimum needed to do Mars. Minimizing development effort.

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Re: Fast transits and aerocapture
« Reply #18 on: 10/29/2016 08:57 AM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

Where would you see those other refuelling positions?


L1/L2 is the obvious option. But there are at least two others.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #19 on: 10/29/2016 09:08 AM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

Where would you see those other refuelling positions?


L1/L2 is the obvious option. But there are at least two others.

I find it very doubtful they can do efficient aerobraking with such a heavy payload and very fast entry. Maybe with aerobraking into orbit first.

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Re: Fast transits and aerocapture
« Reply #20 on: 10/29/2016 09:16 AM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

Where would you see those other refuelling positions?


L1/L2 is the obvious option. But there are at least two others.

I find it very doubtful they can do efficient aerobraking with such a heavy payload and very fast entry. Maybe with aerobraking into orbit first.

So do I, 300 tonnes is probably pushing it initially.

Note the presentation is carefully worded to say "Cargo to Mars", not cargo landed on Mars. It is talking about the  Spaceship transfer capacity in terms of delta-v, not the landing capacity.

Offline guckyfan

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Re: Fast transits and aerocapture
« Reply #21 on: 10/29/2016 12:09 PM »
There is another issue I thougt about. They will want a fast transfer for crew. I think they will also want to test Mars entry of a ship with a similar speed and similar mass before they send people. That would limit the mass of the first cargo ship. They could send two in 2022, one fast and one on a slow trajectory with 300t.

But that may stretch their resources so early in the development. Maybe 1 cargo with 150t fast in 2022. 1 crew fast in 2024 plus one cargo 300t in 2024. Distribution of cargo in a way that it would not endanger the crew if they lose the big cargo ship.

Offline envy887

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Re: Fast transits and aerocapture
« Reply #22 on: 10/29/2016 07:44 PM »
Note the presentation is carefully worded to say "Cargo to Mars", not cargo landed on Mars. It is talking about the  Spaceship transfer capacity in terms of delta-v, not the landing capacity.

Why then would the presentation explicitly show the amount of delta-v reserved for landing 450 tonnes of payload?

Offline Vultur

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Re: Fast transits and aerocapture
« Reply #23 on: 10/30/2016 12:16 AM »
Their is a great irony involved in mars return trajectories, a trajectory that allows the vehicle to make one round trip every synod will involve a VERY long duration is space or nearly 1.3 years for the return leg.  This is clearly unacceptable for human flight being longer then any human has ever spent in space in one stretch and that was in LEO which is far milder.

'Clearly unacceptable' to whom? To current NASA, sure, but probably not to private efforts ~10 years from now.

It is only marginally longer than the longest Mir stay (over 14 months). Sure that was in LEO, but zero-gravity is the same there, and the radiation isn't that bad. (Higher than NASA accepted astronaut doses, sure, but those are very conservative.)

Offline Robotbeat

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Re: Fast transits and aerocapture
« Reply #24 on: 10/30/2016 01:07 AM »
If you refuel more often, you can STILL send 450 tons on a fast trajectory.

Where would you see those other refuelling positions?


L1/L2 is the obvious option. But there are at least two others.

I find it very doubtful they can do efficient aerobraking with such a heavy payload and very fast entry. Maybe with aerobraking into orbit first.

So do I, 300 tonnes is probably pushing it initially.

Note the presentation is carefully worded to say "Cargo to Mars", not cargo landed on Mars. It is talking about the  Spaceship transfer capacity in terms of delta-v, not the landing capacity.
Disagree.

Again, you can use some propellant for slowing down and only aerocapture into Mars orbit (perhaps elliptical), then refuel again.

From the presentation, it seemed clear to me the 450tons was for payload to the ground. It would take much fuller tanks to enable that (hence more refueling in multiple places), but it's most certainly possible. Supersonic retropropulsion is uniquely scalable. If you have enough propellant, you can land a lot.

As far as SpaceX "not really thinking through" some of these other options, I strongly disagree. They've thought through a very wide trade space. What was presented was just the core of their approach, not anywhere close to the limit of their analysis or the architecture's flexibility.

A single person devoted to crawling and analyzing the trade space could generate an enormous multitude of options. With a team of people working on this, each option can be analyzed and considered in some significant depth.

Not that there are no holes anywhere in their analysis. For instance, solar flare radiation is fairly isotropic and anyway spirals around field lines that come in at an angle from the Sun, so pointing the tanks either to the Sun or really anywhere won't guard from most flare radiation. Luckily, you can just reposition supplies and shelter in the center of the ship to get more than sufficient shielding.

But anyway, architecturally, we know from L2 that they've considered a LOT of options.
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Offline Impaler

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Re: Fast transits and aerocapture
« Reply #25 on: 10/30/2016 03:00 AM »
Their is a great irony involved in mars return trajectories, a trajectory that allows the vehicle to make one round trip every synod will involve a VERY long duration is space or nearly 1.3 years for the return leg.  This is clearly unacceptable for human flight being longer then any human has ever spent in space in one stretch and that was in LEO which is far milder.

'Clearly unacceptable' to whom? To current NASA, sure, but probably not to private efforts ~10 years from now.

It is only marginally longer than the longest Mir stay (over 14 months). Sure that was in LEO, but zero-gravity is the same there, and the radiation isn't that bad. (Higher than NASA accepted astronaut doses, sure, but those are very conservative.)

Musk has all but admitted it himself with his emphasis on a fast transit time to mars to outrun the health issues inherent in deep space, to speak nothing of the human factors of confinement for that length of time.  The radiation dosages are not just higher then NASA acceptable dosages they are significantly higher, your looking at an extra year in which dosages are not reduced by shielding on mars and more time for solar flares to occur which even if shielded add to cumulative dosage.  Lastly the fact that a vehicle and it's mission might be private in no way negates NASA or the FFA's regulatory power or responsibility to see that the trip is up to safety standards, if it doesn't meet their standards their astronauts won't use it, and they will never let civilians fly on something that they won't put their own people on.

Offline vapour_nudge

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Re: Fast transits and aerocapture
« Reply #26 on: 10/30/2016 03:33 AM »
There is another issue I thougt about. They will want a fast transfer for crew. I think they will also want to test Mars entry of a ship with a similar speed and similar mass before they send people. That would limit the mass of the first cargo ship. They could send two in 2022, one fast and one on a slow trajectory with 300t.

But that may stretch their resources so early in the development. Maybe 1 cargo with 150t fast in 2022. 1 crew fast in 2024 plus one cargo 300t in 2024. Distribution of cargo in a way that it would not endanger the crew if they lose the big cargo ship.
Hmm. A lot of extreme optimism here. So, within 5 years SpaceX have to develop and man rate a new rocket, test it, create all the infrastructure to build it in the first place, send all that cargo and then crew, which all needs to land without a hitch and the crew too and then that has to be set up and readied for further transits. And all this while they are yet investigating another unforeseen failure of a medium lift rocket.

They're doing great things but if it happens at all, it is a long way off and fast transits are just one small thing. If there were the same optimism for the economy we'd be in a good place. I'd like to say I hope I'm wrong but I just don't see any of it happening within ten years if at all

Fast transits wouldn't be a problem if we were aiming at the Moon or some goal more obtainable.
Having ranted all that, aero capture needs more focus to get the probes into a working orbit more quickly. I'd like to see a lot more probes and science perhaps using the full use of Musks's rocket payload capability before wasting any money on silly adventures like sending crew to Mars
« Last Edit: 10/30/2016 03:41 AM by vapour_nudge »

Offline gospacex

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Re: Fast transits and aerocapture
« Reply #27 on: 10/30/2016 05:32 AM »
Their is a great irony involved in mars return trajectories, a trajectory that allows the vehicle to make one round trip every synod will involve a VERY long duration is space or nearly 1.3 years for the return leg.  This is clearly unacceptable for human flight being longer then any human has ever spent in space in one stretch and that was in LEO which is far milder.

'Clearly unacceptable' to whom? To current NASA, sure, but probably not to private efforts ~10 years from now.

It is only marginally longer than the longest Mir stay (over 14 months). Sure that was in LEO, but zero-gravity is the same there, and the radiation isn't that bad. (Higher than NASA accepted astronaut doses, sure, but those are very conservative.)

Musk has all but admitted it himself with his emphasis on a fast transit time to mars to outrun the health issues inherent in deep space, to speak nothing of the human factors of confinement for that length of time.  The radiation dosages are not just higher then NASA acceptable dosages they are significantly higher, your looking at an extra year in which dosages are not reduced by shielding on mars and more time for solar flares to occur which even if shielded add to cumulative dosage.  Lastly the fact that a vehicle and it's mission might be private in no way negates NASA or the FFA's regulatory power or responsibility to see that the trip is up to safety standards, if it doesn't meet their standards their astronauts won't use it, and they will never let civilians fly on something that they won't put their own people on.

I sure hope US government has no power to decide how people can or cannot risk their own lives. (Risking other people's lives is another matter).

Offline Impaler

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Re: Fast transits and aerocapture
« Reply #28 on: 10/30/2016 06:10 AM »

I sure hope US government has no power to decide how people can or cannot risk their own lives. (Risking other people's lives is another matter).

Selling a transport service IS risking other peoples lives.  If Musk himself wants to ride in the rocket that would be risking his own life, once he starts selling a service his has to meet safety standards no matter what kind of waver people sign.

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Re: Fast transits and aerocapture
« Reply #29 on: 10/30/2016 06:25 AM »
Note the presentation is carefully worded to say "Cargo to Mars", not cargo landed on Mars. It is talking about the  Spaceship transfer capacity in terms of delta-v, not the landing capacity.

Why then would the presentation explicitly show the amount of delta-v reserved for landing 450 tonnes of payload?

I think that makes my point. This is in terms of delta-v, there may be other constraints which limit the amount of cargo landed. There are at least two constraints which potentially limit cargo to lower than 450 tonnes.

First, cargo density, 450 tonnes at 0.2 tonne/m3 is 2250 m3 of cargo, we don't know the usable cargo volume of the spaceship but it is possibly less than that.

Second, heatshield and general EDL performance, the 450 tonnes payload might only be possible for 4th or 5th generation heatshield technology (ITS will use 3rd generation PICA-X).

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Re: Fast transits and aerocapture
« Reply #30 on: 10/30/2016 06:46 AM »

So do I, 300 tonnes is probably pushing it initially.

Note the presentation is carefully worded to say "Cargo to Mars", not cargo landed on Mars. It is talking about the  Spaceship transfer capacity in terms of delta-v, not the landing capacity.
Disagree.

Again, you can use some propellant for slowing down and only aerocapture into Mars orbit (perhaps elliptical), then refuel again.

From the presentation, it seemed clear to me the 450tons was for payload to the ground. It would take much fuller tanks to enable that (hence more refueling in multiple places), but it's most certainly possible. Supersonic retropropulsion is uniquely scalable. If you have enough propellant, you can land a lot.

I think we are slightly talking across each other. I think 450 tonnes cargo is an eventual stretch aim, not a short term goal.

Eventually, there will be cargo transfer in orbit - 150 tonnes is a lot of cargo to transfer (it takes the crew of ISS a  day or two to unload 2 tonnes from Dragon).

Eventually, there will be refueling in other places than LEO and Mars surface - Mars orbit, L1/L2, etc.

Eventually, there will be improvements in EDL.

But none of these are needed short term and are a distraction from the large number of things that are needed over the next 20 years.

Offline Vultur

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Re: Fast transits and aerocapture
« Reply #31 on: 10/30/2016 07:30 AM »
Musk has all but admitted it himself with his emphasis on a fast transit time to mars to outrun the health issues inherent in deep space, to speak nothing of the human factors of confinement for that length of time.

By the nature of a colonization vehicle, return passengers will be much fewer than outbound, and the vehicle is big.

Also, people over-state the confinement issues IMO; people are greatly variable in this regard, and Mars colonists will be heavily self-selected for not being bothered by confinement. Plenty of people I know already spend the great majority of their waking hours in a chair staring at a screen...

(And consider the Antarctic winter quarters in the 1900s and 10s, over a dozen people in a small hut for months...)


Quote
Lastly the fact that a vehicle and it's mission might be private in no way negates NASA or the FFA's regulatory power or responsibility to see that the trip is up to safety standards,

NASA has no regulatory power, and currently the FAA has very little authority over the commercial space industry due to a Congressional moratorium. This was extended to 2023... I see no reason to expect it necessarily won't be extended again (and again). 2023 is late enough to see if Musk's plans look likely to pan out... if they do, I think there will be enough public enthusiasm to make "government interference" look unpopular and therefore unlikely.

Anyway, this is a colonization vehicle; coming back to Earth is an edge case  ;)

EDIT: incomplete sentence
« Last Edit: 10/30/2016 07:31 AM by Vultur »

Offline Robotbeat

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Re: Fast transits and aerocapture
« Reply #32 on: 10/30/2016 06:43 PM »
Space is not safe. Period.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Impaler

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Re: Fast transits and aerocapture
« Reply #33 on: 10/30/2016 09:52 PM »
Musk has all but admitted it himself with his emphasis on a fast transit time to mars to outrun the health issues inherent in deep space, to speak nothing of the human factors of confinement for that length of time.

By the nature of a colonization vehicle, return passengers will be much fewer than outbound, and the vehicle is big.

Also, people over-state the confinement issues IMO; people are greatly variable in this regard, and Mars colonists will be heavily self-selected for not being bothered by confinement. Plenty of people I know already spend the great majority of their waking hours in a chair staring at a screen...

(And consider the Antarctic winter quarters in the 1900s and 10s, over a dozen people in a small hut for months...)


Quote
Lastly the fact that a vehicle and it's mission might be private in no way negates NASA or the FFA's regulatory power or responsibility to see that the trip is up to safety standards,

NASA has no regulatory power, and currently the FAA has very little authority over the commercial space industry due to a Congressional moratorium. This was extended to 2023... I see no reason to expect it necessarily won't be extended again (and again). 2023 is late enough to see if Musk's plans look likely to pan out... if they do, I think there will be enough public enthusiasm to make "government interference" look unpopular and therefore unlikely.

Anyway, this is a colonization vehicle; coming back to Earth is an edge case  ;)

EDIT: incomplete sentence

The congressional moratorium is not going to be extended indefinitely and would never be a basis for unregulated wild-west colonization of mars, that is pure fantasy as is the notion that public opinion will be behind the colonization to such a degree that it will be free from any safety or regulatory standards.

Offline JamesH65

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Re: Fast transits and aerocapture
« Reply #34 on: 10/31/2016 01:55 PM »
Musk has all but admitted it himself with his emphasis on a fast transit time to mars to outrun the health issues inherent in deep space, to speak nothing of the human factors of confinement for that length of time.

By the nature of a colonization vehicle, return passengers will be much fewer than outbound, and the vehicle is big.

Also, people over-state the confinement issues IMO; people are greatly variable in this regard, and Mars colonists will be heavily self-selected for not being bothered by confinement. Plenty of people I know already spend the great majority of their waking hours in a chair staring at a screen...

(And consider the Antarctic winter quarters in the 1900s and 10s, over a dozen people in a small hut for months...)


Quote
Lastly the fact that a vehicle and it's mission might be private in no way negates NASA or the FFA's regulatory power or responsibility to see that the trip is up to safety standards,

NASA has no regulatory power, and currently the FAA has very little authority over the commercial space industry due to a Congressional moratorium. This was extended to 2023... I see no reason to expect it necessarily won't be extended again (and again). 2023 is late enough to see if Musk's plans look likely to pan out... if they do, I think there will be enough public enthusiasm to make "government interference" look unpopular and therefore unlikely.

Anyway, this is a colonization vehicle; coming back to Earth is an edge case  ;)

EDIT: incomplete sentence

The congressional moratorium is not going to be extended indefinitely and would never be a basis for unregulated wild-west colonization of mars, that is pure fantasy as is the notion that public opinion will be behind the colonization to such a degree that it will be free from any safety or regulatory standards.

Whoever said there would be no safety or regulatory standards? There will be safety, there will be standards. Just lower/different ones that would be acceptable to the general public here on Earth, by necessity. Because as someone above said, Space is dangerous.

I used to race cars. That is, by definition, dangerous. You sign forms stating you accept the risk. Not only that, I maintained them myself(!). However, there are still safety standards, but by their very nature, those standards are different to those that govern road cars. My race car has no ABS, no airbags, limited crash protection (compared with a modern road car). It does however, have safety features not usually seen on a road car. Roll cage, full harness seatbelts, in built extinguishers etc.

The point? Different scenarios need different rules. Don't judge an interplanetary transport system with the same mindset as you judge an airliner.

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