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#60
by
wannamoonbase
on 05 Mar, 2008 12:51
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iamlucky13 - 4/3/2008 9:57 PM
The SRG is much more efficient, and so requires less plutonium and a smaller radiator, but it also introduces more moving parts and some minor added vibrations and is (I believe) completely untested in space applications.
SRG are interesting for sure. But someone is going to have to fly a SRG test bed project before it ever gets included as a critical component of a billion dollar mission.
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#61
by
Kaputnik
on 05 Mar, 2008 13:02
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iamlucky13 - 5/3/2008 12:48 AM
Kaputnik - 1/3/2008 1:09 PM
How do the plume issues scale with size? What I'm thinking of here is a larger, human scale, rover dropped via skycrane. With roof-mounted descent propulsion system would it be feasible to delete the whole bridle system in favour of a rigid system... sort of a 'roof rack' I suppose!
I can't answer that directly, but if a "skycrane" were chosen for larger rover missions, you can in theory just lengthen the tether. I think the main concern would be ensuring that you can pay out enough cable in the time you have been heat-shield separation and touch-down.
An overhead thruster has to fire at an angle to avoid blasting the cargo. The greater the angle, the greater the losses from opposing components of the thrust force. The longer the tether, the lower the angle you can use, both because the total clearance increases and the plume dissipates.
Another option is side-mounted thrusters, with the payload sitting in a protective enclosure that ends up suitably close to the ground, but then you end up with a much larger volume to package in the aeroshell and the launch vehicle, especially since the enclosure has to provide room to deploy the vehicle after landing.
By the way, MSL will weigh something like 800 kg. The Lunar rovers had a dry weight of only 210 kg and had a 500 kg payload capacity. Of course, the lunar rovers only needed to survive a few miles of driving and carry loads in 1/6 gravity, but an unpressurized human Mars rover might not weigh too much more than MSL. And with humans dexterity available, such a rover might be unpacked in decent-sized pieces from a more traditional lander and assembled on the surface.
What I was thinking was that the plume effects might be less as you scale up, which could help to allow a shorter bridle or even a rigid system. That's a good point about the angle though.
Since Mars payloads have to be relativley 'fluffy' (i.e. low density) there is quite a bit of room inside the aeorshell, and it should be easy enough to have the thrusters mounted on outriggers, keeping them clear of the payload.
I didn't know the LRV was so light- amazing, really. Of course a Mars mission will last many, many times longer and I wonder if there will even be a need for a small unpressurised rover. There would certainly need to be a much larger one capable of supporting a crew for days or weeks at a time, otherwise you'll be spending eighteen months in basically the same place, which is pretty unrewarding.
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#62
by
Ronsmytheiii
on 17 Mar, 2008 00:08
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Wil it go up on a 401 Atlas V or another variant?
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#63
by
Jim
on 17 Mar, 2008 00:21
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541
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#64
by
Analyst
on 10 Oct, 2008 16:48
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Press conference today. Mission very likely to be delayed to a 2010 or 2011 launch. Maybe downscoped too. Hopefully not canceled.
Analyst
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#65
by
Chris Bergin
on 10 Oct, 2008 18:50
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3pm (EDT - not sure) presser....is not looking good it seems. Over budget and behind schedule.
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#66
by
Ronsmytheiii
on 10 Oct, 2008 19:00
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3pm (EDT - not sure) presser....is not looking good it seems. Over budget and behind schedule.
Will it be on NASA TV? right now (3pm on the east coast) it is ISS coverage replay
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#67
by
Ronsmytheiii
on 10 Oct, 2008 19:03
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(Media-Newswire.com) - WASHINGTON -- NASA will host a media teleconference at 3 p.m. EDT, Friday, Oct. 10, to brief reporters after a meeting held by the agency's administrator concerning the Mars Science Laboratory, or MSL. The meeting is to discuss technical and budget issues.
The mission, scheduled to launch in 2009, will assess a variety of scientific objectives, including whether Mars had, or has today, an environment able to support microbial life. The rover will carry the largest, most advanced suite of instruments for scientific studies ever sent to the Martian surface.
The briefing participants are:
- James Green, director of the Planetary Division in the Science Mission Directorate at NASA Headquarters in Washington
- Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters
- Michael Meyer, Mars Program lead scientist at NASA Headquarters
To participate in the teleconference, reporters in the U.S. should call 1-866-398-6118 and use the pass code "MSL." International reporters should call 1-517-308-9407.
Audio of the teleconference will be streamed live at:
http://www.nasa.gov/newsaudio
For more information about MSL, visit:
http://mars.jpl.nasa.gov/msl
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#68
by
DaveS
on 10 Oct, 2008 19:03
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3pm (EDT - not sure) presser....is not looking good it seems. Over budget and behind schedule.
Will it be on NASA TV? right now (3pm on the east coast) it is ISS coverage replay
No. It's an audio teleconference:
http://www.nasa.gov/news/media/newsaudio/index.htmlBookmark the page for future reference.
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#69
by
Ronsmytheiii
on 10 Oct, 2008 19:04
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3pm (EDT - not sure) presser....is not looking good it seems. Over budget and behind schedule.
Will it be on NASA TV? right now (3pm on the east coast) it is ISS coverage replay
No. It's an audio teleconference: http://www.nasa.gov/news/media/newsaudio/index.html
Bookmark the page for future reference.
Audio link comes up with a RAM file which doesn't work.
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#70
by
Analyst
on 10 Oct, 2008 19:23
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Link works for me.
They are - for now - still planning for 2009. No discussion of costs - these issues have not been resolved. They are "looking" for money within the MEP, then SMD, then ... No definitive answers. They are confident they can technically launch in 2009 - but need more money to keep the schedule.
Analyst
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#71
by
Analyst
on 10 Oct, 2008 19:26
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Sidenote: Outer planets fagship decision between Saturn/Titan and Jupiter/Europa planned in January.
Analyst
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#72
by
Kaputnik
on 11 Oct, 2008 18:13
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Fingers crossed for MSL!
Some pretty pictures from Mars might tide people over during 'the gap'....
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#73
by
iamlucky13
on 14 Oct, 2008 18:10
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I have to wonder how much the late decision to add a sample cache contributed to the continuing budget and time issues.
It would be nice to hear a more detailed status report, what work is currently in progress, what the pacing elements are, etc.
Analyst, thanks for the note about the next flagship (check your spelling
) mission. Either target should be outstanding. I vote for Saturn.
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#74
by
rdale
on 14 Oct, 2008 18:14
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The Planetary Science Subcommittee produced many reports from a meeting last week - they recommend not launching in 2009 because of the cost overruns and explain why...
http://www.lpi.usra.edu/pss/
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#75
by
iamlucky13
on 14 Nov, 2008 02:00
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#76
by
Pheogh
on 13 Nov, 2010 00:25
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Does anyone know the purpose of the large crossbar running between the sets of wheels over the top of the main chassis?
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#77
by
Jim
on 13 Nov, 2010 02:48
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Tranfers motion from one side to the other
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#78
by
apace
on 28 Jun, 2011 12:19
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I found no answer on the MSL web page, so my question here to the MSL Sky Crane and I hope someone knows it.
Why using a Sky Crane, where a lot can go wrong instead of a normal landing. If I watch the animations, there should be no problem to land the rover attached to the Sky Crane part and after landing releasing it. Of course, there need extended legs, but such a landing would be easier in my opinion and the way to go for future landings.
Greetings,
Daniel
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#79
by
Jim
on 28 Jun, 2011 12:35
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I found no answer on the MSL web page, so my question here to the MSL Sky Crane and I hope someone knows it.
Why using a Sky Crane, where a lot can go wrong instead of a normal landing. If I watch the animations, there should be no problem to land the rover attached to the Sky Crane part and after landing releasing it. Of course, there need extended legs, but such a landing would be easier in my opinion and the way to go for future landings.
Greetings,
Daniel
Don't understand the question. Also, it is a descent stage and not a skycrane
) mission. Either target should be outstanding. I vote for Saturn.