Author Topic: Red Dragon Discussion Thread (2)  (Read 387764 times)

Offline CuddlyRocket

Re: Red Dragon Discussion Thread (2)
« Reply #620 on: 03/10/2017 03:38 am »
It would suck if you blew it off and it landed right in the path of your ramp that was supposed to deploy afterwards from inside!

Reminds me of Venera 14, when the camera's lens cap was ejected and landed right where the soil compressibility experiment was to measure the soil, so it actually measured the compressibility of the lens cap!

Offline Negan

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Re: Red Dragon Discussion Thread (2)
« Reply #621 on: 03/16/2017 09:55 pm »
It will be very interesting to see how all that interior space is utilized for Mars missions.

Try driving that out of the little hatch...

A bigger hatch is possible. At one time Elon Musk said it is possible to increase the hatch width to include the area now used for windows, that is a big hatch.

WAG 60" by 26" opening and that's only if they didn't make the hatch any bigger for crew.

Offline FutureSpaceTourist

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Re: Red Dragon Discussion Thread (2)
« Reply #622 on: 03/18/2017 09:42 pm »
Quote
[Paul] Wooster [SpaceX] on slip of Red Dragon from 2018 to 2020: have a lot of things on our plate at SpaceX; nothing specific to this mission. #LPSC2017

https://twitter.com/jeff_foust/status/843230457483411462

Offline FutureSpaceTourist

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Re: Red Dragon Discussion Thread (2)
« Reply #623 on: 03/18/2017 10:04 pm »
Cross-posting as shows some on-going Red Dragon work, although discussion of landing site specifics probably best in original landing site thread:

Quote
Paul Wooster, SpaceX, on Mars landing site selection: looking at sites at latitudes < 40˚, elevation as low as possible. #LPSC2017

https://twitter.com/jeff_foust/status/843229275025227777

Quote
Wooster: identified several candidate sites, but many likely too rocky. Arcadia region looks promising. #LPSC2017

https://twitter.com/jeff_foust/status/843229571642286081

Edit: from context I think he's talking about Red Dragon landing site

Offline Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #624 on: 03/20/2017 12:23 am »
Cross-posting as shows some on-going Red Dragon work, although discussion of landing site specifics probably best in original landing site thread:

Quote
Paul Wooster, SpaceX, on Mars landing site selection: looking at sites at latitudes < 40˚, elevation as low as possible. #LPSC2017

https://twitter.com/jeff_foust/status/843229275025227777

Quote
Wooster: identified several candidate sites, but many likely too rocky. Arcadia region looks promising. #LPSC2017

https://twitter.com/jeff_foust/status/843229571642286081

Edit: from context I think he's talking about Red Dragon landing site

There's no paper by Wooster listed at LPSC which starts tomorrow.  Some sort of pre-conference event?

Arcadia is about as flat as they come, would looking like the Viking 2 landing site but perhaps less rocky (there is no medium sized crater nearby). Very boring, but probably with shallow subsurface ice.
Apologies in advance for any lack of civility - it's unintended

Offline Robotbeat

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Re: Red Dragon Discussion Thread (2)
« Reply #625 on: 03/20/2017 01:23 am »
Boo. I'd do Mellas Chasma. Just 10 degrees off the equator, so super good solar power capability (can use a simplified single axis tracker), plus it's very low altitude, has multiple possible sources of water nearby, and the views are INCREDIBLE.
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 Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #626 on: 03/20/2017 02:13 am »
Boo. I'd do Mellas Chasma. Just 10 degrees off the equator, so super good solar power capability (can use a simplified single axis tracker), plus it's very low altitude, has multiple possible sources of water nearby, and the views are INCREDIBLE.

Melas has been proposed many times but always misses out because of landing site issues.  It's probably too risky for a first landing by unproven technology.  Safety first.
Apologies in advance for any lack of civility - it's unintended

Offline Robotbeat

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Re: Red Dragon Discussion Thread (2)
« Reply #627 on: 03/20/2017 02:20 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).
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 Phil Stooke

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Re: Red Dragon Discussion Thread (2)
« Reply #628 on: 03/20/2017 02:31 am »
It may not be very efficient to set up a GPS constellation (even half a dozen satellites) for a once every 2 year event.  We can probably do just as well if not better, based on recent work for the Moon and Mars, by matching image data to pre-loaded maps of the target area. 

Offline Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #629 on: 03/20/2017 02:39 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).

There isn;t going to be a Mars GPS by 2020.;) So without that the ellipse must quite large.

I have not seen any estimates of a landing ellipse size for Red Dragon. I doubt that it is gong to be better than 10 km radius
Apologies in advance for any lack of civility - it's unintended

Offline sdsds

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Re: Red Dragon Discussion Thread (2)
« Reply #630 on: 03/20/2017 02:46 am »
[...] matching image data to pre-loaded maps of the target area. 

This is a very good point and is easily overlooked by long-time experts because the capability is actually rather new. It might take a fair bit of processing power and data storage, but with each Mars launch opportunity Moore's Law tilts the decision in favor of this type of approach....
— 𝐬𝐝𝐒𝐝𝐬 —

Offline Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #631 on: 03/20/2017 02:50 am »
[...] matching image data to pre-loaded maps of the target area. 

This is a very good point and is easily overlooked by long-time experts because the capability is actually rather new. It might take a fair bit of processing power and data storage, but with each Mars launch opportunity Moore's Law tilts the decision in favor of this type of approach....

Unless of course the atmosphere is too hazy for it to work.....
Apologies in advance for any lack of civility - it's unintended

Offline Robotbeat

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Re: Red Dragon Discussion Thread (2)
« Reply #632 on: 03/20/2017 02:56 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).

There isn;t going to be a Mars GPS by 2020.;) So without that the ellipse must quite large.

I have not seen any estimates of a landing ellipse size for Red Dragon. I doubt that it is gong to be better than 10 km radius
It's possible to use the existing telecom assets at Mars for this purpose. It has been done before by a rover.
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 Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #633 on: 03/20/2017 03:15 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).

There isn;t going to be a Mars GPS by 2020.;) So without that the ellipse must quite large.

I have not seen any estimates of a landing ellipse size for Red Dragon. I doubt that it is gong to be better than 10 km radius
It's possible to use the existing telecom assets at Mars for this purpose. It has been done before by a rover.

For landing?  if so, which mission?
Apologies in advance for any lack of civility - it's unintended

Offline Robotbeat

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Re: Red Dragon Discussion Thread (2)
« Reply #634 on: 03/20/2017 03:17 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).

There isn;t going to be a Mars GPS by 2020.;) So without that the ellipse must quite large.

I have not seen any estimates of a landing ellipse size for Red Dragon. I doubt that it is gong to be better than 10 km radius
It's possible to use the existing telecom assets at Mars for this purpose. It has been done before by a rover.

For landing?  if so, which mission?
It was done after landing since it's experimental, of course. One of the MERs.

And the idea is mostly getting a good fix before atmospheric interface. Do that, and the gyro drift while doing EDL will be fairly small. Should get within a kilometer.
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 Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #635 on: 03/20/2017 03:47 am »
Good point for a first landing. But by all rights, with a fully propulsive (plus heatshield) landing, they should be able to get an arbitrarily small landing ellipse if they could get a good location fix from satellites.

I think a few small areosynchronous areolocation satellites should be launched soon. Or maybe a small version of SpaceX's constellation. If SpaceX's constellation is anything like Iridium's, it should be possible to get better than 10m location fix (Iridium can do about 5m fix, single-sigma, with a little effort).

There isn;t going to be a Mars GPS by 2020.;) So without that the ellipse must quite large.

I have not seen any estimates of a landing ellipse size for Red Dragon. I doubt that it is gong to be better than 10 km radius
It's possible to use the existing telecom assets at Mars for this purpose. It has been done before by a rover.

For landing?  if so, which mission?
It was done after landing since it's experimental, of course. One of the MERs.

And the idea is mostly getting a good fix before atmospheric interface. Do that, and the gyro drift while doing EDL will be fairly small. Should get within a kilometer.

Given  uncertainties in the launch time and date there may not be the right orbiters in position atthe right time.  So  this method, even if valid, can't be counted on. 
Apologies in advance for any lack of civility - it's unintended

Offline Phil Stooke

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Re: Red Dragon Discussion Thread (2)
« Reply #636 on: 03/20/2017 03:55 am »
"It's possible to use the existing telecom assets at Mars for this purpose. It has been done before by a rover."

I had not heard of this, and I would be very interested to hear more details of it if you can track them down.  As we know, GPS requires views to multiple satellites, and I would have thought that could very rarely happen at Mars with the existing orbiters.  But an experiment could be timed to make it work, I suppose.

Offline Phil Stooke

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Re: Red Dragon Discussion Thread (2)
« Reply #637 on: 03/20/2017 04:08 am »
"And the idea is mostly getting a good fix before atmospheric interface. Do that, and the gyro drift while doing EDL will be fairly small. Should get within a kilometer."

Uncertainty during EDL is much more about uncertainty in the atmospheric conditions.  Pressure, temperature, dust loading, winds, it's not the Moon.  That's why terrain relative navigation is going to be used to help 2020 get where it's going - AKA comparing images to a pre-loaded map.  And people are planning to use TRN on the Moon too (Astrobotic is testing it and there's plenty of literature about it now).  It's fairly mature and no need for a GPS-style constellation.  Go the image route!

Offline Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #638 on: 03/20/2017 04:43 am »
"And the idea is mostly getting a good fix before atmospheric interface. Do that, and the gyro drift while doing EDL will be fairly small. Should get within a kilometer."

Uncertainty during EDL is much more about uncertainty in the atmospheric conditions.  Pressure, temperature, dust loading, winds, it's not the Moon.  That's why terrain relative navigation is going to be used to help 2020 get where it's going - AKA comparing images to a pre-loaded map.  And people are planning to use TRN on the Moon too (Astrobotic is testing it and there's plenty of literature about it now).  It's fairly mature and no need for a GPS-style constellation.  Go the image route!

So long as there isn't a big dust storm.....
Apologies in advance for any lack of civility - it's unintended

Offline Robotbeat

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Re: Red Dragon Discussion Thread (2)
« Reply #639 on: 03/20/2017 04:59 am »
"And the idea is mostly getting a good fix before atmospheric interface. Do that, and the gyro drift while doing EDL will be fairly small. Should get within a kilometer."

Uncertainty during EDL is much more about uncertainty in the atmospheric conditions.  Pressure, temperature, dust loading, winds, it's not the Moon.  That's why terrain relative navigation is going to be used to help 2020 get where it's going - AKA comparing images to a pre-loaded map.  And people are planning to use TRN on the Moon too (Astrobotic is testing it and there's plenty of literature about it now).  It's fairly mature and no need for a GPS-style constellation.  Go the image route!
Problems with wind, etc, are addressed by ditching parachutes and using active guidance with propulsion the whole way down. With onboard gyro for dead reckoning (plus radar for terminal landing), the drift is small enough to get much, much smaller (order of magnitude) landing ellipse than currently done. But sure, add a mapping capability.
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

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