NASASpaceFlight.com Forum
Robotic Spacecraft (Astronomy, Planetary, Earth, Solar/Heliophysics) => Mars Science Laboratory (MSL) and Mars 2020 Rover Section => Topic started by: AndyMc on 06/02/2007 10:55 am
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Brief weblog item from the Planetry Society, plus link to some cool videos.
http://www.planetary.org/blog/article/00000988/
http://mars.jpl.nasa.gov/msl/gallery/videos.html
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That has to be the coolest promotional video ever produced by NASA. The Battlestar Galactica style camera work. The sound of the wind whistling over the Martian plains. Just fantastic.
We were talking about how to interest people in space exploration? This is it, my friends.
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*Confused*
This video was last year: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=5418&start=1
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Ah well, it's still cool...
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Actually it seems like they've added on 20 seconds to the end.
Naraht - 2/6/2007 12:48 PM
Ah well, it's still cool...
Speaking of cool, Mars and the Bowie classic always works well:
http://www.youtube.com/watch?v=jldQ7Z-LawQ
That's a personal thing I have about videos like this. General public need something they know before they'll even bother watching videos like the MSL one.
This linked video has 33,000 views and I bet 90 percent of those views weren't people searching for Mars Rovers.
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I know its juvenile but I just love the laser at the end :D
The whole thing is very cool. MSL looks like an all round larger more capable vehicle than the MER's, but still based on the obviously proven and robust MER tech. Still, watching all those moving parts in that dusty environment makes me nervous.
There seems to be several versions of the video, the longest seems to be 7 1/2 mins with a rock core sample being taken and analysed at the end.
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Chris Bergin - 2/6/2007 1:03 PM
Naraht - 2/6/2007 12:48 PM
Ah well, it's still cool...
Speaking of cool, Mars and the Bowie classic always works well:
http://www.youtube.com/watch?v=jldQ7Z-LawQ
That's a personal thing I have about videos like this. General public need something they know before they'll even bother watching videos like the MSL one.
This linked video has 33,000 views and I bet 90 percent of those views weren't people searching for Mars Rovers.
That is definitely a neat video. Well synched to the lyrics. If I had made it, though, I would have cut off the song before the second half. It definitely becomes a lot more downbeat there and I don't think that's the message the creator wanted to send...
I take your point about needing something to entice people to watch the video. However, you also have to offer them a certain amount of information once you have the eyeballs there. Someone watching the Bowie video might not necessarily know that it was showing real probes at the beginning, what stage of development they were in, who was launching them etc. The video mixes reality and fantasy, which is great for viewers like us, but if you're hoping to do publicity for NASA then you have to offer a little more.
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It's cool to see how this gets to the surface. Any reason why they aren't bouncing this one with airbags?
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Too big. MER was near the limit of the airbag method
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STSFan10 - 2/6/2007 3:02 PM
It's cool to see how this gets to the surface. Any reason why they aren't bouncing this one with airbags?
Too heavy. Airbags don't scale up well. Pathfinder was small enough to use airbags alone, but even the MERs required some rocket braking.
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Pathfinder had rockets too
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Great piece of kit. Have NASA/JPL produced any comprehensive presentations on the MSL?
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Wow. That was a lot more detailed than the video from a few months ago. All that ChemMin sampling stuff looks very prone to failure. Good stuff. I can't wait to see this thing fly.
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Paul Howard - 2/6/2007 8:26 PM
Great piece of kit. Have NASA/JPL produced any comprehensive presentations on the MSL?
Not really - other than what's at the MSL web pages. The rover still hasn't been fully built or tested yet, and they're still fine-tuning the descent stage design (including the 'skycrane maneuver' hardware); also, JPL/MSL folks still have to finalize their landing location (because MRO is still taking full detailed images of the large # of proposed MSL landing sites).
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The period after aeroshell release with crane and rover under retros looks particularly dicey, especially with weight/COG issues due to combined vehicles. Not to mention the hover/repell maneuver. Bravo to software program designers if they pull this off.
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That is really impressive...and it looks like a much more complex landing than MER.
By the way, not to hijack the thread...are the MERs still chugging along? (I haven't heard anything that said they died)
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Yes, both are.
http://marsrovers.jpl.nasa.gov/home/index.html
Analyst
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rsp1202 - 3/6/2007 9:26 AM
aeroshell release with crane and rover .
Propery "descent stage and rover"
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I can't wait for the documentary on PBS (in HD, of course) showing the testing.
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I wonder how well the crane can hover in a strong crosswind.
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Is there any remaining controversy (amongst decision makers) on the inclusion of the RTG?
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Mogster - 3/6/2007 4:04 PM
I wonder how well the crane can hover in a strong crosswind.
Do they have crosswinds on Mars? (I have no idea).
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CriX - 4/6/2007 1:44 AM
Is there any remaining controversy (amongst decision makers) on the inclusion of the RTG?
nope, just need to finish the paperwork
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Jason Davies - 4/6/2007 11:28 AM
Mogster - 3/6/2007 4:04 PM
I wonder how well the crane can hover in a strong crosswind.
Do they have crosswinds on Mars? (I have no idea).
A cross wind is a wind from an other direction than headwind
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This is becoming a useful thread, so it's now changing call signs to MSL Q&A.
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Jason Davies - 4/6/2007 10:28 AM
Do they have crosswinds on Mars? (I have no idea).
If I rememebr correctly if one of (or both(?)) the MER rovers didn't have an option to correct for some cross winds it may have crashed on landing. I believe the gusts were strong right before landing...
I saw a vid somewhere of animation of a simulated crash due to high gusts just before landing.. neat but scary.. (forget where I saw it!!)
I read a concern of the MSL rover was having it coming down and getting dragged sideways and "breaking the wheels"..as opposed to being dragged forward and back and have the wheels move... I'm fascinated by the crane..be cool if it works (I'm giving them benefit the doubt and say it will :) )..opens up some neat possibilites!!
cheers
jb
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MER added a system to deal with winds, TIRS
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"TIRS, the Transverse Impulse Rocket System, was designed to add a last-second attitude correction to protect the landing craft's airbags from self-induced excess horizontal velocity resulting from multibody excitation due to wind shears and gusts."
MSL looks to be using a robust RCS system to handle such contingencies, rather than a retro-pack.
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How confident can the designers be that there won't be a pendulum motion that would send the rover smacking into the surface sideways? What sort of horizontal velocity do they expect to achieve?
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I would guess that they've already compensated for leveling out the descent stage prior to lowering the lander, and that they've got more than enough lateral control to minimize oscillations at the altitudes prior to touchdown/release.
This isn't hit-or-miss - these folks have done lots of work to prove this system.
IOW - if it doesn't work, it will be something well beyond what they could have planned for... a sudden support hardware or thruster failure, a total failure to one of the pyro primary/backup signal lines, etc.
Compared to the MER EDL complexity to land and deploy, MSL entry/descent/landing is overall actually simpler hardware/reliability-wise.
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MKremer - 4/6/2007 7:54 PM
Compared to the MER EDL complexity to land and deploy, MSL entry/descent/landing is overall actually simpler hardware/reliability-wise.
What do you mean? MSL EDL seems much more complex with that crane. Do you mean that all the mechanisms behind deploying the airbags and then the rovers were more complex? (not to sound antagonistic, i'm just curious)
The software (control) side of the MSL EDL does seem much more complex. I'm sure they'll debug it thoroughly.
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Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?
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Do a Google search for:
six minutes of terror
six minutes of hell
...to read about all the entry/deployment/landing parameters/pyros/configuration each of the MER landers (not to mention to rovers themselves) had to survive.
With MSL, once the parachute deploys, and the heatshield goes away, there's only 5 *major* things needed to accomplish a successful landing - descent thrusters ignited and positive thrust; suspension deployment and release of the MSL itself (from the descent stage and lowered via the cables); touchdown and release of the suspension cables; rover mast elevation and other vehicle deployments.
Then drive away.
With the MER EDL, once the main parachute deployed and location/drift was computed there were extra necessary steps - airbag pyro ignitions and inflation; lander cable cut at the correct point (retro/drift rockets fired); computation that the bouncing/rolling had stopped and it was OK to deflate the airbags; retract the airbags as much as possible; lander petal opening; rover mast elevations and other vehicle deployments (solar panel 'wings'); rover elevation for wheel/suspension deployment; pyro charge cut of lander cable connections to the rover; rover movement off the lander and to Mars' surface.
Then drive away.
Compare the two.
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Stowbridge - 4/6/2007 10:38 PM
Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?
There is no "crane" It is the descent stage.
They are current testing the repelling portion of the sequence with the "scarecrow" rover and having land on different terrain
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BTW, looking at the pic Jim posted, the top of the 'triangle' in that picture is around 6 feet high - MSL is a *BIG* rover.
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Stowbridge - 4/6/2007 5:38 PM
Is there any word on test schedules? I'm assuming the crane will require some form of testing before flying?
After watchig Armadillos LLC1 test video, i was thinking they could do the exact landing sequence tests with VTVL vehicles like these. However Pixel currently only takes a payload of 25KG which falls way short of lifting the MSL.
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Some cool photos that have been provided to us:
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Wow, they weren't kidding. That thing is huge.
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You could drive to work in that! Huge.
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I'll give em' 45K for it :bleh: The look on my coworker's faces when they see it in the parking lot will be well worth it.
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And some video (cell phone). You have to open this in a quicktime player.
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Just a note, the sample handling hardware has changed
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Less complex, hopefully?
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all of it is on the turret of the arm.
The RCS and descent thrusters have changed and the mobility system is deployed during the repel
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IMAGE_00234.jpg is great. Looks like the Rover is looking at MSL with a look of "and you are??" ;)
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Jim - 6/6/2007 7:03 PM
all of it is on the turret of the arm
So, more similar to what the Viking scoop/shaker did than the complex, multi-arm sample processing/transfers in the video?
The RCS and descent thrusters have changed and the mobility system is deployed during the repel
I already sort of figured the former would be in some flux until the final hardware construction contracts were signed.
Huh, interesting (concerning the suspension/mobility deployment timing). Wonder what made them decide to change the timing for that? (some risk of pyro signalling/activation while still mated to the descent module, maybe?)
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MKremer - 6/6/2007 8:21 PM
So, more similar to what the Viking scoop/shaker did than the complex, multi-arm sample processing/transfers in the video?
The arm turret will have the APXS, microscope imager, surface removal tool, powdering drill (instead of corer) and a handler that scoops regolith and receives samples from the drill. The only things that remain on the rover body are the instrument inlets (3) and bit box for the drill. the rock crusher has been eliminated
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Thanks for the info.
Good thing the "corer" and "rock crusher" are no more - it was a lot of extra hardware mass (and less mass is a *good thing*) - plus eliminating all the descision-making software required to monitor each surface sample target to keep the corer/crusher from being damaged/destroyed by possible soft-then-hard/soft-then-waytoohard sudden transitions during coring.
I have to admit I looked wide-eyed in amazement as the video showed all the extra rotations the video-MSL sample handling rotor had to make just to get the materials in position for both grinding and depositing, and then more contortions to deposite samples into the science instruments.
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http://www.space.com/news/ap-080228-flagship-mars-overruns.html
Erm, presumably it's a mistake when they write that MSL was supposed to use ET insulation???
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Kaputnik - 29/2/2008 4:07 PM
http://www.space.com/news/ap-080228-flagship-mars-overruns.html
Erm, presumably it's a mistake when they write that MSL was supposed to use ET insulation???
No, ET has/had SLA (super lightweight ablative) on feedline brackets.
"Foam and super lightweight ablative are being removed from the first four of the five brackets and replaced with foam only, Hale said. Less foam on the brackets is acceptable for the shuttle’s ascent, he added. Bracket foam is about one-inch thick while the underlying super lightweight ablative is about one-half-inch thick, but denser than foam. The final shape of the replacement foam is still under review." marshallstar.msfc.nasa.gov/8-30-07.pdf
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Cool video, but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving. I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.
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grakenverb - 1/3/2008 1:30 PM
Cool video, but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving. I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.
How would the "legs" fit in the aeroshell? Short legs would have plume problems. Apollo LM, Surveyor dropped that last few feet
the skycrane method is applicable to many packages.
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How deep will MSL dig for its samples? I was just wondering because so far other Mars robots haven't detected Boron, Manganese, Molybdenum, Nickel, Copper, Zinc, or other micronutrients that plants need in the soils so far sampled. I was thinking that they just need to dig deeper.
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scienceguy - 1/3/2008 2:16 PM
How deep will MSL dig for its samples? I was just wondering because so far other Mars robots haven't detected Boron, Manganese, Molybdenum, Nickel, Copper, Zinc, or other micronutrients that plants need in the soils so far sampled. I was thinking that they just need to dig deeper.
It isn't going to dig. It can make trenches with its wheels.
Phoenix will dig
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Jim - 1/3/2008 6:34 PM
grakenverb - 1/3/2008 1:30 PM
Cool video, but i have to wonder why they just don't put legs on the "sky crane" and have it land, then lower the rover to the surface once the whole thing has stopped moving. I know that much smarter people than myself have conceived of this thing, but it all looks rather Rube Goldberg to me.
How would the "legs" fit in the aeroshell? Short legs would have plume problems. Apollo LM, Surveyor dropped that last few feet
the skycrane method is applicable to many packages.
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!
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I just hope that the "Keep it Simple, Stupid" theory hasn't been abandoned for some cool-looking, complicated, engineers delight.
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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.
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grakenverb - 1/3/2008 4:18 PM
I just hope that the "Keep it Simple, Stupid" theory hasn't been abandoned for some cool-looking, complicated, engineers delight.
The landing bag system is maxed out
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Does anyone know whether the multi-mission RTG or a Stirling Radioisotope Generator (SRG) were chosen for power? Both were on the table a couple years ago, but I never heard anything more about it.
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.
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MMRTG
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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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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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Wil it go up on a 401 Atlas V or another variant?
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541
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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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3pm (EDT - not sure) presser....is not looking good it seems. Over budget and behind schedule.
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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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(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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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.
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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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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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Sidenote: Outer planets fagship decision between Saturn/Titan and Jupiter/Europa planned in January.
Analyst
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Fingers crossed for MSL!
Some pretty pictures from Mars might tide people over during 'the gap'....
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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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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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Would it be better to keep posting MSL updates in the Q&A thread, or go start a new thread in the US unmanned section?
MSL website has photos up of a coupling test between the partially completed descent stage and the very barebones rover chassis. Very excited to see flight hardware in progress! Geeze...even folded up the thing is a monster.
http://mars.jpl.nasa.gov/msl/spotlight/20081112.html
The Planetary Society Blog has two more photos of the hardware, including a really good one from above:
http://www.planetary.org/blog/article/00001737/
Other minor news tidbits that I don't think have been mentioned
Aeroshell and heatshield were delivered a couple weeks ago:
http://mars.jpl.nasa.gov/msl/spotlight/20081027.html (pictures)
"Bridle Umbilical Device" (cable spooling) tests have been progressing
http://mars.jpl.nasa.gov/msl/spotlight/20081023.html (video)
Lastly, Malin Space Science Systems has delivered both the Mars Descent Imager (MARDI) and the Mars Hand Lens Imager (MHALI), a macro camera for the robotic arm (pictures):
http://www.msss.com/press_releases/mahli_delivery/index.html
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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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Tranfers motion from one side to the other
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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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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
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Don't understand the question. Also, it is a descent stage and not a skycrane
My question was, why to develop an additional method (sky crane) of lowering something to the ground and not use a more traditional method like a normal lander with long legs as we can see in the animations for future human landings (where the payload is between the descent stage rocket motors). Or can this sky crane also be used for more heavy payloads?
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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
JPL calls the manuever Skycrane. Not the actual descent stage hardware.
This a a pretty good article on the reasons for going this route.
http://www.space.com/3163-heavy-lift-helicopter-inspires-nasas-mars-lander.html
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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
JPL calls the manuever Skycrane. Not the actual descent stage hardware.
This a a pretty good article on the reasons for going this route.
http://www.space.com/3163-heavy-lift-helicopter-inspires-nasas-mars-lander.html
thanx!
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I like the article, but I think it's a little bit wrong about some of the reasons for using a Skycrane approach.
Pointing to a hazard of traditional landings on legs, the article states "Failure of any of the thrusters to cease firing at just the right time could send the lander hopping across the surface, as happened with NASA's Surveyor robotic lunar lander in 1967." To my knowledge, one Surveyor hopped -- Surveyor 6 (http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Surveyor_06) -- but the hop was intentional. Well after landing, the engines were briefly re-ignited. After re-landing, the probe photographed its previous footprint (http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=6664).
The next paragraph reads "Getting a rover off a legged lander after touchdown poses additional challenges, Steltzner said. Ramps are customarily used, but there is no guarantee that the martian terrain and an imprecise landing will not conspire to deny the rover a safe path to the surface. On the 1996 Mars Pathfinder mission, for example, only one of the landing platform's two ramps opened onto a clear path for the tiny Sojourner rover. NASA could have just as well found both paths blocked."
In the case of Pathfinder, wasn't the ramp blocked by one of the airbags rather than by martian terrain (maybe that should be "areain"? :)), as the article suggests?
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I still don't understand the advantage of lowering the payload (rover) on a set of cables and making the descent bus hover then fly away.
What is the reason for separating the two prior to landing? It seems like a very time-critical event which could lead to all sorts of instability (i.e. the rover swinging on its cables or getting hung up) immediately prior to landing. Why not land together, then separate once you are stable on the surface.
It would mean the bus having to have landing legs or some sort of "slide off" mechanism to allow the rover to get out from underneath, but would seem to save on winches, cables and flyaway fuel.
(I understand why the rover is at the bottom of the lander - stability & the risks of driving down a ramp).
I have little doubt there is a good reason - but what?
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STS-200, I feel the same way. Time-critical "must works" make my skin crawl.
However, I'm guessing (as an armchair engineer) a factor in favor of skycrane is the 'clean sheet' landing. That is, once the rover is on the surface, a fairly standard pyro cuts the cables, and the rover is ready to go -- there's no "exit the lander" transition. From my limited reading, this exit maneuver has been a challenging part of past rover mission planning, it doesn't contribute any return science or data, and adds significant uncertainty/risk.
The skycrane sounds risky at first, but I think it actually adds little risk -- the descent rockets have to work right anyway, or you don't even get to the skycrane phase. The rover oscillating on the cable is possible, but the descent stage should be able to damp that out -- at least, oscillation is something that can be planned for, modeled, and tested. If the cable unreels partially (or not at all?), I'm guessing the descent stage will just keep descending until the rover is on the ground. The cable-cutter has to work, but NASA has a huge history with that operation.
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Good relevant points, but I think one of STS-200's observations is that you could have a clean-sheet landing without the crane: with the the rocket-and-landing-craft assembly rigidly attached to the top of the rover, touch down, sever the connection between the two, and have the top part fly away.
I'm wondering if maybe it's a control issue. Presumably, especially since the rover will be touching down on wheels designed for traversing rather than on landing gear designed for shock absorption, the touch down needs to be very gentle. Maybe it's easier to get a lander to hover at constant altitude while the rover is winched down than to get a lander to descend very slowly. Just a guess.
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Let's not forget that the rover needs to stay as clean as possible at landing - free from flying dust (+ rocks) and rocket exhaust contamination. Having the descent/landing module hovering well above the rover when it touches down is probably the best compromise solution, I think.
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Limiting the amount of surface debris kicked up by the rocket engines makes sense to me. It's not clear to me, though, that winching the rover down while the rocket engines are burning isn't going to result in a lot of plume contamination.
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Limiting the amount of surface debris kicked up by the rocket engines makes sense to me. It's not clear to me, though, that winching the rover down while the rocket engines are burning isn't going to result in a lot of plume contamination.
Better a very small amount than a whole heck of a lot if the descent module lands with the rover. And additional shields or coverings, etc. required to protect against the rocket plumes/backblast/landing debris are additional mass penalties against the rover itself.
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I hadn't thought of the dust issue. Thanks
As you all say - no doubt it is a compromise - or a series of compromises. I wondered whether it might have anything to do with the packaging of the complete spacecraft (i.e. there isn't room for some critical piece/mass distribution is wrong if you do it another way).
Does anyone know if there is any intention to control the final descent of the bus, or is it just set up to "fly away until you run out of fuel".
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Does anyone know if there is any intention to control the final descent of the bus, or is it just set up to "fly away until you run out of fuel".
Fly away. As soon as the harness is released it's going to start ascending rather quickly anyway... then within 2 seconds it's supposed to roll/pitch to 45 degrees at full thrust and maintain that attitude until the fuel is gone.
The latest landing simulation video includes that flyaway command.
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I hadn't thought of the dust issue. Thanks
As you all say - no doubt it is a compromise - or a series of compromises. I wondered whether it might have anything to do with the packaging of the complete spacecraft (i.e. there isn't room for some critical piece/mass distribution is wrong if you do it another way).
Does anyone know if there is any intention to control the final descent of the bus, or is it just set up to "fly away until you run out of fuel".
There is no real control of the descent stage after the cables are cut. The guidance system is in the rover
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As you all say - no doubt it is a compromise - or a series of compromises. I wondered whether it might have anything to do with the packaging of the complete spacecraft (i.e. there isn't room for some critical piece/mass distribution is wrong if you do it another way).
It really boils down to two things
a. Rolling off a lander has many risks
b. the rover already has "landing gear"
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It really boils down to two things
a. Rolling off a lander has many risks
b. the rover already has "landing gear"
OK - that makes sense:
Mass of landing legs needed for the complete unit > Mass of cable & winch.
Many thanks.
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Does MSL use the downward facing camera to avoid placing the rover on top of a large boulder, or will it be used solely for mapping the immediate locale after landing?
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If I'm reading the elevation data correctly, Curiosity's landing site in Gale crater is 2-3km lower in elevation than either of the MER sites.
Is the sky expected to be any bluer due to the greater atmospheric density?
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Does MSL use the downward facing camera to avoid placing the rover on top of a large boulder, or will it be used solely for mapping the immediate locale after landing?
No, there is no hazard avoidance. Per one of the rover drivers on UMSF.
Camera is for documentation and radar is for altimetry.
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Does anyone here know about what kind of twisting motion they might expect from the skycrane bridles. In other words I am dying to find any information about what kind of tolerance there is to the difference in angle between the descent stage and the rover might be expected?
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What are the degraded landing conditions, in the event of impact beyond nominal survival levels? Even if the vehicle's wheels/chassis is damaged/destroyed, even if the vehicle does not come down right-side-up, what communications [omni?] and power [nuc] capabilities might remain to allow SOME command and control? And what indications might be received that suggest such a degraded landing has occurred?
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Does anyone here know about what kind of twisting motion they might expect from the skycrane bridles. In other words I am dying to find any information about what kind of tolerance there is to the difference in angle between the descent stage and the rover might be expected?
Since the three bridles all come together at a common point where they enter the descent stage, there should be little or no effect due to twisting, but since it will nominally be stabilized in pitch and yaw and with zero horizontal velocity there isn't much that could initiate twisting or swaying. In addition because of the outward cant of the descent engines it can land on a 15deg slope with a .55m rock under the wrong end of the rover and still not have issues with plume impingement.
This document has the best info on EDL: http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/41629/1/10-1775.pdf
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Where is the TMI stage now, at the time of EDL? Is it visible from Gale Crator as well as Earth? If so, in the future couldn't it carry a communications transponder for "live" coverage of the landing?
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Where is the TMI stage now, at the time of EDL? Is it visible from Gale Crator as well as Earth? If so, in the future couldn't it carry a communications transponder for "live" coverage of the landing?
Gone and dead. It was never pointed at Mars
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These hazcam images looks... dirty. I mean, like some dirt is on camera eye. This worries me. Did rover got sandblasted more than they expected? What about rest of instruments?
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These hazcam images looks... dirty. I mean, like some dirt is on camera eye. This worries me. Did rover got sandblasted more than they expected? What about rest of instruments?
They still have their dustcover on them - they took the picture through the dustcover. They'll pop up the cover and it'll be fine ;)
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Ah, transparent dustcover. Dev team thinks of everything, indeed.
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What's NASA's protocol in the event that - let's say - fossilized bones are found? Would this be announced the day it's found, or will it be held from public knowledge, pending confirmation and internal debate or even presidential approval?
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Jason Davies - 4/6/2007 10:28 AM
Do they have crosswinds on Mars? (I have no idea).
If I rememebr correctly if one of (or both(?)) the MER rovers didn't have an option to correct for some cross winds it may have crashed on landing. I believe the gusts were strong right before landing...
I saw a vid somewhere of animation of a simulated crash due to high gusts just before landing.. neat but scary.. (forget where I saw it!!)
I read a concern of the MSL rover was having it coming down and getting dragged sideways and "breaking the wheels"..as opposed to being dragged forward and back and have the wheels move... I'm fascinated by the crane..be cool if it works (I'm giving them benefit the doubt and say it will :) )..opens up some neat possibilites!!
cheers
jb
Well the question only begs more questions regarding a Martian gravity, atmospheric density and landing. A) What would terminal velocity be for a free fall? B) What is the difference in FORCE for a 200kph wind ;Earth/Mars? C) What is the atmospheric density profile through altitude?
I suspect there are far greater influences when trying to fly in an Earth atmosphere.
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What's NASA's protocol in the event that - let's say - fossilized bones are found? Would this be announced the day it's found, or will it be held from public knowledge, pending confirmation and internal debate or even presidential approval?
not even worth acknowledging
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B) What is the difference in FORCE for a 200kph wind ;Earth/Mars? C) What is the atmospheric density profile through altitude?
general rule of thumb for me is that Mars atmosphere is about 1000 times less dense than on Earth. So a 200 km/h wind is about a 1000 times less strong, so feels like a 0.2 km/h wind. However, 200 km/h dust particles can still be very abrasive.
pressure is greater at the bottom of a crater (up to 4 times greater I believe, depending on crater depth), so winds would be 250 times less strong than on Earth, at most.
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What's NASA's protocol in the event that - let's say - fossilized bones are found?
I get first dibs... See my EBay page for more details...
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Noting the mention in the NSF article that the entry guidance software had some heritage in Apollo, are there any decent papers (either public or L2) which discuss the guidance software development?
Cheers,
Andy
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Now that it has been shown to work, i wonder what another copy of SkyCrane+basic rover platform ( minus the science package) would cost, if built right now.
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Wind force is proportional to the atmospheric density, but it scales as the Square of the wind velocity. Official observed gust velocities have been in the 120-160 km/h range, with higher altitude dust movement at 400-480 km/hr. So peak wind forces can still be substantial due to high wind velocities even though the atmospheric density is low.
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Are the upcoming MAVEN & ExoMars orbiters both designed to operate as relay satellites, just that I am concerned by the recent issues amongst the existing orbiters & redundancy in this area would seem sensible?
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Are the upcoming MAVEN & ExoMars orbiters both designed to operate as relay satellites, just that I am concerned by the recent issues amongst the existing orbiters & redundancy in this area would seem sensible?
All US orbiters must carry the relay package.
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Are the upcoming MAVEN & ExoMars orbiters both designed to operate as relay satellites, just that I am concerned by the recent issues amongst the existing orbiters & redundancy in this area would seem sensible?
All US orbiters must carry the relay package.
Thanks.
Well that covers MAVEN what about ExoMars which isn't US, will it carry this as well?
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Most likely would be on NTRS if it's available publicly.
http://ntrs.nasa.gov/search.jsp?N=0&Ntk=All&Ntt=MSL%20entry%20guidance&Ntx=mode%20matchallpartial
Thanks, I should have done more digging but was at work at the time. Hopefully at some point we'll get fulltext of http://ntrs.nasa.gov/search.jsp?Ntx=mode+matchall&Ntk=All&N=0&Ntt=20060026281
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Now that it has been shown to work, i wonder what another copy of SkyCrane+basic rover platform ( minus the science package) would cost, if built right now.
Go to the planetary science decadal survey website. Look up the mission study on the MAX-C rover mission. Details in there.
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What would it take to put 3 comm satellites in stationary equitorial orbits equally spaced around Mars? How much would that speed the investigations performed by these robot missions? By manned missions?
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What would it take to put 3 comm satellites in stationary equitorial orbits equally spaced around Mars? How much would that speed the investigations performed by these robot missions? By manned missions?
Money.
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What would it take to put 3 comm satellites in stationary equitorial orbits equally spaced around Mars? How much would that speed the investigations performed by these robot missions? By manned missions?
The better part of a billion dollars.
The Mars Telecommunications Orbiter, a single dedicated relay orbiter in a high orbit that would have provided longer comm windows and larger coverage areas, was cancelled in the design phase a few years ago due to other projects going over budget, and because NASA decided the benefit of extra available bandwidth wasn't that big.
Given the slowdown (also budget related) in mission pace compared to plans when MTO was conceived, the impact of cancellation has arguably been even smaller than originally expected.
It's possibly a question that will be re-examined if we commit to a manned mission, as much for reducing no-comms periods as due to total bandwidth availability.
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Are the upcoming MAVEN & ExoMars orbiters both designed to operate as relay satellites...?
All US orbiters must carry the relay package.
Well that covers MAVEN what about ExoMars which isn't US, will it carry this as well?
Yes, ExoMars has the Electra relay package
http://en.wikipedia.org/wiki/ExoMars_Trace_Gas_Orbiter
(I know, Wikipedia is a poor reference, but find me a counter-ref and I'll put the effort in!)
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Hi,
do we know version of OS VxWorks(latest is 6.9) which is "using" MSL ? Thanks
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Has there been any public release of the RAD data from the flight out or Sol 0? I'd be more doubtful of the latter given this morning's briefing, but I haven't found anything about the flight out either. I would have thought they had plenty of time / opportunity to send & process that data already.
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So where is MSL exactly, like lat/long coordinates. Now that we have an MRO picture of its location that information has got to be available somewhere.
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So where is MSL exactly, like lat/long coordinates. Now that we have an MRO picture of its location that information has got to be available somewhere.
(assuming I got the numbers correct) ;)
http://forum.nasaspaceflight.com/index.php?topic=29612.msg938376#msg938376
And to add (because I wrote it down, but didn't post): N114E
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So where is MSL exactly, like lat/long coordinates. Now that we have an MRO picture of its location that information has got to be available somewhere.
Nailing Down Curiosity's Landing Site
This image shows the location (green) where scientists estimate NASA's Curiosity rover landed on Mars within Gale Crater, based on images from the Mars Descent Imager (MARDI). The landing estimates derived from navigation and landing data agree to within 660 feet (200 meters) of this MARDI estimate.
http://www.nasa.gov/mission_pages/msl/multimedia/pia16008.html
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Due to communication lag and relay considerations, can you give us a time frame on when a typical event is scheduled, sent up, performed, sent down, and reviewed.
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Due to communication lag and relay considerations, can you give us a time frame on when a typical event is scheduled, sent up, performed, sent down, and reviewed.
There should be some info on MER on the web
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What's NASA's protocol in the event that - let's say - fossilized bones are found? Would this be announced the day it's found, or will it be held from public knowledge, pending confirmation and internal debate or even presidential approval?
not even worth acknowledging
I used bones as an extreme example, but - if anything - fossilized bacteria is a possibility (unlikely possibility, yes, but possible).
What is NASA's protocol, if found. I remember that the Antartica Mars rock find was kept secret for some time, while multiple teams studied it for confirmation, and the news reached the President before the public news briefing. I would imagine that, since then, NASA had codified a procedure.
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Hello
Are the High Gain Antenna now in in corect Position to Communitate
directly to earth?
Best wiches Rocke
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Hello
Are the High Gain Antenna now in in corect Position to Communitate
directly to earth?
Best wiches Rocke
Should be deployed, but probably still in work at this moment to get it pointed to Earth:
http://mars.jpl.nasa.gov/msl/news/whatsnew/index.cfm?FuseAction=ShowNews&NewsID=1295
"August 7: Curiosity Gets More Looks at its Surroundings; Health Checks Continue
"Curiosity is healthy as it continues to familiarize itself with its new home in Gale Crater and check out its systems. The team's plans for Curiosity checkout today included raising the rover's mast and continued testing of its high-gain antenna, whose pointing toward Earth will be adjusted on Sol 2. Science data were collected from Curiosity's Radiation Assessment Detector, and activities were performed with the Rover Environmental Monitoring Station instrument. Curiosity transmitted its first color image from the surface of Mars, from the Mars Hand Lens Imager, or MAHLI, showing part of the north rim of Gale Crater. Additional calibration images were received from Curiosity's Navcam and Mastcam. All systems are go for deployment of the rover's remote sensing mast on Sol 2, followed by a 360-degree pan by the rover's Navcam. The Mastcam will also be calibrated against a target image on the rover. NASA's Mars Reconnaissance Orbiter returned a spectacular image of Curiosity's landing site, depicting the rover, parachute, back shell, heat shield and descent stage. Data were received from both NASA's Mars Reconnaissance Orbiter and Mars Odyssey."
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Possibly a stupid question.
Can the rover drive during the night?
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Possibly a stupid question.
Can the rover drive during the night?
Apparently the answer is technically yes, but the power supply is already loaded with keeping the rover warm and trickle charging the battery at night.
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Possibly a stupid question.
Can the rover drive during the night?
Yes (well, in theory, but I'm not sure if in practice navigation would be functional), but they probably won't. This was covered during one of the Q&A sessions. They don't have the energy to keep the rover awake all the time, much less drive all the time, because they still have to manage their energy balance even with the RTG versus the solar cells.
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Is there a mass breakdown available of the various components of MSL? What's the heaviest component aside from the chassis?
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What's NASA's protocol in the event that - let's say - fossilized bones are found? Would this be announced the day it's found, or will it be held from public knowledge, pending confirmation and internal debate or even presidential approval?
not even worth acknowledging
I used bones as an extreme example, but - if anything - fossilized bacteria is a possibility (unlikely possibility, yes, but possible).
What is NASA's protocol, if found. I remember that the Antartica Mars rock find was kept secret for some time, while multiple teams studied it for confirmation, and the news reached the President before the public news briefing. I would imagine that, since then, NASA had codified a procedure.
For the question of if there is a protocol for keeping such findings a secret for political purposes:
There is not.
There is a protocol, however, that protects the hard work of those directly involved in a project so that they get the first chance at getting credit for findings their hardware made possible. Normal practice is that they are allowed to keep the data only available to those involved in the project for up to one year, then it has to be made available to any interested party.
It is also regular practice, when you think you have discovered something significant, to keep it to yourself until you can increase the confidence in your discovery. It's embarrassing to publicly claim (http://www.enterprisemission.com/images/LAxpo/10.jpg) there are photos of a bunny rabbit on Mars, only to have others point out it's really just a piece of fabric from your lander. (http://marsrovers.nasa.gov/spotlight/opportunity/b19_20040304.html)
Well...it would be embarrassing at least if Richard Hoagland had any sense of shame.
The president often gets briefed before major findings are published because:
1.) He's the boss. NASA reports to him. Usually the boss wants to hear about big news first.
2.) The public often looks to the president to discuss the relevance of a finding whenever anything important happens, so it is helpful to give his office time to understand what the finding and decide if they want to comment on it.
3.) Getting the president excited enough to come to your press conference makes you look really important, and that's good for your prestige. This is a double-edged sword, however, as you can be perceived as overhyping your findings, which hurts your credibility.
In the case of the Mars meteorite, Administrator Goldin briefed President Clinton a week beforehand that they were about to announce evidence that life may have existed on Mars in the past. This was a little over a week before the paper detailing the findings was to be published, and several months after it had been submitted.
http://www.nytimes.com/1996/08/07/us/clues-in-meteorite-seem-to-show-signs-of-life-on-mars-long-ago.html?pagewanted=2
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Is Curiosity going to examine its own crashed descent stage? In addition to getting us some really cool crash pictures, it would also present the opportunity to study some of that big pile of dirt the stage kicked up. Maybe the stage will have even dug some distance down into the ground, allowing subsurface sampling.
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Is Curiosity going to examine its own crashed descent stage? In addition to getting us some really cool crash pictures, it would also present the opportunity to study some of that big pile of dirt the stage kicked up. Maybe the stage will have even dug some distance down into the ground, allowing subsurface sampling.
Asked at the second press conference. Answer: no.
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Is Curiosity going to examine its own crashed descent stage? In addition to getting us some really cool crash pictures, it would also present the opportunity to study some of that big pile of dirt the stage kicked up. Maybe the stage will have even dug some distance down into the ground, allowing subsurface sampling.
Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
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Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
Thanks for the responses, especially for the reason, which would have been my next question. :)
One more question. Is this a new requirement or something unique to the descent stage? Because Opportunity investigated its own heat shield. Even if the heat shield didn't have fuel on it, it still would presumably have had chemicals from the trip through the atmosphere.
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When we look at these pictures from Mars how much are they "lightened" up from what the human eye would see? In other words, how bright would it be on the surface of Mars as compared to the surface of earth during the daytime? Is this what it would look like to an astronaut or would it be dimmer?
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The risk of contamination isn't for hydrazine it's for everything except the tungsten weights.
I don't know how many times JPL will have to answer this same question.
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When we look at these pictures from Mars how much are they "lightened" up from what the human eye would see? In other words, how bright would it be on the surface of Mars as compared to the surface of earth during the daytime? Is this what it would look like to an astronaut or would it be dimmer?
There is no fixed light level for the human eye. Our eyes adjust and adapt to light levels continuously, and also have a much wider dynamic range than almost any digital camera. But what you see is probably close to how it would appear in person.
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When we look at these pictures from Mars how much are they "lightened" up from what the human eye would see? In other words, how bright would it be on the surface of Mars as compared to the surface of earth during the daytime? Is this what it would look like to an astronaut or would it be dimmer?
I took some time to quantify that question a while back when I was asked elsewhere.
Sparing all the technical details, the brightness of sunlight at Mars is a little under half the brightness of at earth, but because the human eye can perceive a very wide brightness range, and adjusts very easily to changes in brightness, if you were there, you would not have an impression that it was more than a little bit dimmer. You'd have no trouble seeing at all.
The brightness is equivalent to a lightly overcast day on earth, and actually quite a bit brighter than a typical kitchen, which is usually the best lit room in a house.
If you could perceive two scenes side-by-side, one under earth lighting, and the other under Mars lighting, you would notice the Mars scenario being slightly, but not impressively darker.
All because the human eye is a fantastically capable instrument.
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Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
Thanks for the responses, especially for the reason, which would have been my next question. :)
One more question. Is this a new requirement or something unique to the descent stage? Because Opportunity investigated its own heat shield. Even if the heat shield didn't have fuel on it, it still would presumably have had chemicals from the trip through the atmosphere.
Spirit and Opportunity didn't have any instruments with anywhere close to the sensitivity as those in the Sample Analysis at Mars (SAM) suite. If they contaminate SAM, they'll have trouble telling which molecules are genuine discoveries, and which are from earth.
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Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
Thanks for the responses, especially for the reason, which would have been my next question. :)
One more question. Is this a new requirement or something unique to the descent stage? Because Opportunity investigated its own heat shield. Even if the heat shield didn't have fuel on it, it still would presumably have had chemicals from the trip through the atmosphere.
You do understand the orders of magnitude difference between the seriousness of hydrazine contamination versus the miniscule trace amounts that might be on the heat shield, right?
And to add, since they said there was 106.4 kg 140.6 kg of propellant remaining, and there was (perhaps) some visual evidence of a larger debris field at the descent stage's location (indicating the propellant may have dispersed from the vehicle), there is a high probability of an extreme hazard.
If they can image it from afar (looking down on it), then they may do that (IIRC from the presser they might), so we have a chance to see something (maybe).
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Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
Thanks for the responses, especially for the reason, which would have been my next question. :)
One more question. Is this a new requirement or something unique to the descent stage? Because Opportunity investigated its own heat shield. Even if the heat shield didn't have fuel on it, it still would presumably have had chemicals from the trip through the atmosphere.
1. Future passes of the MRO may show the crash site in greater detail.
2. Different instrumentation on Curiosity vs. MERs, Curiosity more sensitive to contamination issue. Others may be able to elaborate on that.
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Also, the MSL heatshield was instrumented, so less need to actually examine it.
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One more question. Is this a new requirement or something unique to the descent stage? Because Opportunity investigated its own heat shield. Even if the heat shield didn't have fuel on it, it still would presumably have had chemicals from the trip through the atmosphere.
You do understand the orders of magnitude difference between the seriousness of hydrazine contamination versus the miniscule trace amounts that might be on the heat shield, right?
I did recognize that the heat shield is likely to have no hydrazine, or only trace amounts, compared to the descent stage, which is why I said "Even if the heat shield didn't have fuel on it". But surely the heat shield does have all kinds of chemicals caused by heat shield ablation.
Now the possibility of chemicals on the heat shield didn't stop Opportunity from looking at it, which is why I asked the question. In other words, is the contamination risk from a heat shield qualitatively different from the contamination risk from hydrazine? Or is there a new requirement to avoid contamination from any source?
It is also possible that my assumption is wrong and that the heat shield carries no risk of chemical contamination whatsoever; if this is so, I should very much like to learn why.
Spirit and Opportunity didn't have any instruments with anywhere close to the sensitivity as those in the Sample Analysis at Mars (SAM) suite. If they contaminate SAM, they'll have trouble telling which molecules are genuine discoveries, and which are from earth.
Okay, thanks. It sounds like this is would qualify as a new requirement driven by increased instrument sensitivity.
And to add, since they said there was 106.4 kg of propellant remaining, and there was (perhaps) some visual evidence of a larger debris field at the descent stage's location (indicating the propellant may have dispersed from the vehicle), there is a high probability of an extreme hazard.
If they can image it from afar (looking down on it), then they may do that (IIRC from the presser they might), so we have a chance to see something (maybe).
And this is also helpful, as you say that hydrazine contributes a chemical hazard, whereas the heat shield presumably wasn't actually hazardous, even if it could be hypothetically a contamination risk.
So between iamlucky13's and robertross's answers, it sounds like the answer to my question is "both". :)
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RobertRoss- did you introduce a typo on the reported value of 140.6kg hydrazine remaining at DS sep, or is that a new figure estimating how much would have remained after ECO?
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Since use of the laser was brought up today, about how deep into the rock can the laser "dig"?
Does it just vaporize a thin layer off the surface, or can it actually make a pit into the rock?
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Since use of the laser was brought up today, about how deep into the rock can the laser "dig"?
Does it just vaporize a thin layer off the surface, or can it actually make a pit into the rock?
thin layer
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Since use of the laser was brought up today, about how deep into the rock can the laser "dig"?
Does it just vaporize a thin layer off the surface, or can it actually make a pit into the rock?
According to this site, they can etch up to half a millimeter (very much "thin layer" territory) into the surface, and compare how readings change as they do so to see if on the smallest scales there is variation in the rock that tells them a little bit about how it weathers.
http://msl-scicorner.jpl.nasa.gov/Instruments/ChemCam/
It says going that deep takes 500+ laser pulses. Each pulse lasts less than a millionth of a second, but is repeated multiple times per second. A normal analysis would use 50-75 pulses.
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RobertRoss- did you introduce a typo on the reported value of 140.6kg hydrazine remaining at DS sep, or is that a new figure estimating how much would have remained after ECO?
Yes, sorry. Corrected now. Thanks.
(I reverted back to the originally reported Sol 0 landing value of 140.6 kg)
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Here's something for those interested:
They just reported on Canadian television that Weaver industries built the heat shield for MSL (after something about the original (design?) fell through?). They had to keep it under their hats and could only announce it now after landing
I found this article on the net:
http://ephratareview.com/2012/08/weaver-industries-journey-to-mars/
Company:
http://www.weaverind.com
edit: another source/link
http://www.cw15.com/news/local/story/Mars-rover-lands-with-some-help-from-two-local/n2DbbbGJdkyzc4-n8oIcHw.cspx
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How does MSL's power supply work? i.e. how do they get an electric current from the plutonium?
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How does MSL's power supply work? i.e. how do they get an electric current from the plutonium?
Thermocouples.
In a nutshell, dissimilar metals joined together at one end, with the free ends exposed to a different temperature, will experience a small voltage across the free ends. Stack a bunch of them together with a significant heat difference and you can get useful amounts of power.
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
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cool. thx.
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Here's something for those interested:
They just reported on Canadian television that Weaver industries built the heat shield for MSL (after something about the original (design?) fell through?). They had to keep it under their hats and could only announce it now after landing
I found this article on the net:
http://ephratareview.com/2012/08/weaver-industries-journey-to-mars/
Company:
http://www.weaverind.com
edit: another source/link
http://www.cw15.com/news/local/story/Mars-rover-lands-with-some-help-from-two-local/n2DbbbGJdkyzc4-n8oIcHw.cspx
On that note, our friends at Sierra Nevada built the brakes on the skycrane tethers, as well as some gear boxes on Curiosity.
www.sncorp.com/press_more_info.php?id=509
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Just a question about the RAD hardened processors they use on vehicles such as the MSL, is it true they are based on Sapphire rather than Silicon as I saw that quoted somewhere recently?
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heavy duty radiation-hardened processors are usually built on non-conductive substrate with silicon - compare that with conventional processors that are built on a silicon substrate from where the structures are built by etching away the unneeded stuff. Don't know about sapphire, though.
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heavy duty radiation-hardened processors are usually built on non-conductive substrate with silicon - compare that with conventional processors that are built on a silicon substrate from where the structures are built by etching away the unneeded stuff. Don't know about sapphire, though.
Isn't the architecture a lot simpler & build on a larger micron size as well, from what I read it was compared to being akin to what you would see in a home PC CPU about ten years ago?
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Just a question about the RAD hardened processors they use on vehicles such as the MSL, is it true they are based on Sapphire rather than Silicon as I saw that quoted somewhere recently?
http://en.wikipedia.org/wiki/Mars_Science_Laboratory
Computers: The two identical on-board rover computers, called "Rover Compute Element" (RCE), contain radiation-hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. Each computer's memory includes 256 KB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory.[27] This compares to 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory used in the Mars Exploration Rovers.[28]
The RAD750 is a radiation-hardened single board computer manufactured by BAE Systems Electronic Solutions.[1] The successor of the RAD6000, the RAD750 is for use in high radiation environments such as experienced on board satellites and spacecraft.[2] The RAD750 was released in 2001, with the first units launched into space in 2005.[1][3]
The CPU has 10.4 million transistors, nearly an order of magnitude more than the RAD6000 (which had 1.1 million).[3] It is manufactured using either 250 or 150 nm photolithography and has a die area of 130 mm².[1] It has a core clock of 110 to 200 MHz and can process at 266 MIPS or more.[1] The CPU can include an extended L2 cache to improve performance.[3] The CPU itself can withstand 200,000 to 1,000,000 rads (2,000 to 10,000 gray), temperature ranges between –55 °C and 125 °C and requires 5 watts of power.[1][3] The standard RAD750 single-board system (CPU and motherboard) can withstand 100,000 rads (1,000 gray), temperature ranges between –55 °C and 70 °C and requires 10 watts of power.[3]
The RCE computers use the RAD750 CPU (a successor to the RAD6000 CPU used in the Mars Exploration Rovers) operating at 200MHz.[29][30][31] The RAD750 CPU is capable of up to 400 MIPS
http://en.wikipedia.org/wiki/RAD750
Searching for RAD750 and Sapphire gives NO results
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Just a question about the RAD hardened processors they use on vehicles such as the MSL, is it true they are based on Sapphire rather than Silicon as I saw that quoted somewhere recently?
http://en.wikipedia.org/wiki/Mars_Science_Laboratory
Computers: The two identical on-board rover computers, called "Rover Compute Element" (RCE), contain radiation-hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. Each computer's memory includes 256 KB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory.[27] This compares to 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory used in the Mars Exploration Rovers.[28]
The RCE computers use the RAD750 CPU (a successor to the RAD6000 CPU used in the Mars Exploration Rovers) operating at 200MHz.[29][30][31] The RAD750 CPU is capable of up to 400 MIPS
That didn't answer the question.
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About rad hardened computers i wonder if you take a regular (OK, industrial) computer and wrap it with say 5mm of lead - how much rad hardening would that add, compared with the specially built rad hardened computers?
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Robotbeat....
I'm on an iPad and have to use the edit function to add additional copied material...
and you chimed in prior to my last edit
I see no specific reference to using Sapphire in the RAD750, looking several places, (including the manufacturers spec sheet) but with this info, one could search further to confirm an answer.
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MSL came with 6 balance weights that were discarded in the early EDL phase. Why are those weights made of tungsten?
One property that comes to mind when talking about tungsten is its very high melting temperature (3422 C), but why is that useful? After they are discarded, what problems would they caused if they melted?
Is it that they want it to hit the ground as solid to make bigger impact? My understanding is that the kinetic energy delivered would be mostly the same - solid or molten.
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Because Tungsten has a very high density, much higher than lead, for a 'relatively' cheap material. Which minimizes the size of the weights. It's been used as keel weights in some America Cup sailboats for that reason.
Also it's very hard so it's not going to deform under high G loads like lead could and cause any problems when the weights are released.
The high melting point was not a consideration.
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Just a question about the RAD hardened processors they use on vehicles such as the MSL, is it true they are based on Sapphire rather than Silicon as I saw that quoted somewhere recently?
The technology is called Silicon on Sapphire. It consists of a thin layer of monocrystalline silicon that is grown on a sapphire substrate. Sapphire is used because the atomic spacing of Sapphire is very close to the atomic spacing of silicon and makes it possible to grow a monocrystalline silicon layer.
The actual transistors are all still silicon, but the sapphire substrate is an extremely good insulator and eliminates substrate currents from flowing around that occur in a regular bulk silicon wafer. This is extremely important for RAD hard devices because radiation causes these substrate currents that can flip transistor states.
SOS also reduces inter-element capacitances and results in considerably faster transistors than you would get otherwise. This is also important since RAD hard processors and memory use very large transistors to reduce the effects of radiation hits, and large transistors are slower due in large part to parasitic capacitances. Current Intel processors are built with a 22nm feature size, the RAD750 is built with 150nm minimum feature size. So transistors are at least 50 times larger than typical desktop computers.
Edit - 8/11/2012
The MSL computers apparently operate at 133 Mhz, not the often quoted 200 Mhz. The slower clock speed might indicated that these are actually fabricated with 250 nm feature size instead of the smaller 150 nm feature size. Somebody out of JPL would probably have to answer the question of what the process size actually is for the MSL cpus since all I can find is BAE RAD750 product data sheets and requotes from that and not what is actually in the MSL.
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@Randomly thanks for that information.
This new article about the computers onboard the MSL also quotes the 200MHz clock speed again for them?
http://www.spaceflightnow.com/mars/msl/120810computer/
It mentions in here that BAE are currently working on a quad-core CPU which will be order of magnitude faster & more powerful than the current ones in use.
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MSL came with 6 balance weights that were discarded in the early EDL phase. Why are those weights made of tungsten?
One property that comes to mind when talking about tungsten is its very high melting temperature (3422 C), but why is that useful? After they are discarded, what problems would they caused if they melted?
Is it that they want it to hit the ground as solid to make bigger impact? My understanding is that the kinetic energy delivered would be mostly the same - solid or molten.
Because tungsten is very dense. That means the physical dimensions of the weight are small, which means you have more latitude in where you can place it, such as out towards the edge of the vehicle, where it has the greatest moment arm, and therefore you can minimize the mass required for balance.
About rad hardened computers i wonder if you take a regular (OK, industrial) computer and wrap it with say 5mm of lead - how much rad hardening would that add, compared with the specially built rad hardened computers?
I don't remember the source right now, but I was reading a paper the other day discussing the effect of different types of shielding on the radiation exposure at Mars. One of the points mentioned is that lead is effective against solar particles, but not so much galactic cosmic rays...or perhaps I have that backwards. The result being that it can help, but not as much as you'd like.
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@randomly, @imlucky13: Thanks for your detailed answers.
Another 3 questions:
1. MMRTG is powered by Plutionium-238, which produces various types of radiation when decaying. Does it affect RAD in any way? One possibility is that characteristics of MMRTG radiation and any obstacles between MMRTG and RAD are well known, so they can be corrected/taken into account during interpretation of RAD readings. The other is that MMRTG is so well shielded that it does not leak any measurable amounts of radiation. So, how does it work?
2. MMRTG used as power source has minimum lifetime of 14 years. MSL primary mission is envisaged to last around 2 Earth years. I assume that even under most optimistic assumptions, drive system will not last 14 years, so MSL will lose mobility well before 14 years. But is it reasonable to hope that at least some useful data will still be produced in 14 years?
3. http://nuclear.gov/pdfFiles/MMRTG.pdf states that US launched 26 missions including 45 RTGs. That means that some missions had more than one RTG on-board. Which missions had more than one RTG?
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Is Curiosity going to examine its own crashed descent stage? In addition to getting us some really cool crash pictures, it would also present the opportunity to study some of that big pile of dirt the stage kicked up. Maybe the stage will have even dug some distance down into the ground, allowing subsurface sampling.
Asked at the second press conference. Answer: no.
And the main reason: risk of contamination from Hydrazine fuel
There's another reason that hasn't been mentioned yet. There seems to have been a sensible effort to ask where Curiosity intended to go for maximum scientific payoff, and try to put the discarded bits of spacecraft jettisoned on the way to the surface as far away from there as practical. So looking at the descent stage would also take Curiosity away from the most interesting local real estate.
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lead is effective against solar particles, but not so much galactic cosmic rays...or perhaps I have that backwards.
My guess (but a high-confidence one) would be 'more effective against solar'. Solar stuff is produced in less-energetic reactions, and the highest-energy cosmic rays are from extra-solar sources (http://www.sciencemag.org/content/336/6085/1096.summary). So assuming the shielding works better against lower-energy stuff, that gives the 'more effective against solar'.
Noel
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1) Pu-238 is the optimal fuel for RTG's. It requires the minimum shielding of any of the other possibilities. Usually the structure of the RTG is enough and no additional shielding is needed. Now some radiation does escape and I am sure that is taken into account as far as the RAD is concerned.
2) 14 years is a long time so who knows. I would be surprised if the electronics last that long. Actually the RTG's are likely one of the most reliable parts. It's not that they stop after 14 years. The power would have decayed enough that normal operations is no longer possible. The most important of those operations is running the heaters at night. No heaters and the electronics will die relatively quickly from temperature cycling.
3) Most deep space missions have more than 1
Pioneer 10 & 11 had 4 each
The Voyages have three each.
The viking landers had two each
Cassini has three
Galileo had 2
New horizons only has 1
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@Randomly thanks for that information.
This new article about the computers onboard the MSL also quotes the 200MHz clock speed again for them?
The BAE RAD750 product sheet says they can operate UP TO 200 mhz. It covers a number of different versions with speeds of 110 mhz to 200 mhz.
Ben Cichy of JPL says the MSL RAD750s are running at 133 mhz.
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About rad hardened computers i wonder if you take a regular (OK, industrial) computer and wrap it with say 5mm of lead - how much rad hardening would that add, compared with the specially built rad hardened computers?
It's not very effective unfortunately. Some Galactic cosmic rays can penetrate through Meters of lead. Radiation causes damage to the actual devices that is cumulative. It's essentially knocking atoms out of the crystal structure which among other things causes increases in leakage currents in the transistors.
As the radiation damage accumulates the CPU is going to fail at some point. So you want to design it so it lasts as long as possible. You want larger transistors so they can take more damage before they are compromised. You want larger threshold voltage differences and larger voltage swings so it's more tolerant of leakage currents and shifts in transistor threshold voltages from radiation damage. You want lower operating frequencies and so on.
All the technology trends that make current computers so fast, complex, and energy efficient are the same trends that make them even less radiation resistant. For space applications you really need to design computers that are radiation hardened from the ground up. Unfortunately that means you are not going to get state of the art processing power. It's an unfortunate tradeoff that has to be made. They are also very expensive since there is a lot of intensive engineering involved and so few units sold.
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@randomly, @imlucky13: Thanks for your detailed answers.
Another 3 questions:
1. MMRTG is powered by Plutionium-238, which produces various types of radiation when decaying. Does it affect RAD in any way? One possibility is that characteristics of MMRTG radiation and any obstacles between MMRTG and RAD are well known, so they can be corrected/taken into account during interpretation of RAD readings. The other is that MMRTG is so well shielded that it does not leak any measurable amounts of radiation. So, how does it work?
Pu238 decay produces almost exclusively alpha particles which are very easy to shield. A small fraction of the decays produce neutrons from spontaneous fission events, and there are some gamma rays produced further down the decay chain. Both neutrons and gamma are not so easily shielded against but the intensity is fairly low. The radiation from the MMRTG is a small fraction of the background radiation from GCR, probably less than 10%. Also the type of radiation and associated energy levels is known and can be accounted for in the detector.
2. MMRTG used as power source has minimum lifetime of 14 years. MSL primary mission is envisaged to last around 2 Earth years. I assume that even under most optimistic assumptions, drive system will not last 14 years, so MSL will lose mobility well before 14 years. But is it reasonable to hope that at least some useful data will still be produced in 14 years?
It's certainly possible. half life of PU238 is about 88 years so thermal power will drop to half in 88 years, electrical power will drop faster than that due to degradation of the thermocouples, but these things are incredibly durable. The Voyager RTGs are still operating after 35 years in deep space.
The MMRTG on the MSL charges up a battery which is used for driving and running the instruments during the day. If nothing else fails and the battery capacity doesn't degrade to much there is no reason you couldn't still be driving around collecting data 20 years from now.
3. http://nuclear.gov/pdfFiles/MMRTG.pdf states that US launched 26 missions including 45 RTGs. That means that some missions had more than one RTG on-board. Which missions had more than one RTG?
I think you can find that info here
http://solarsystem.nasa.gov/multimedia/downloads/Standard_RPS_Report_Final_011205.pdf
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Pu238 decay produces almost exclusively alpha particles ... A small fraction of the decays produce neutrons from spontaneous fission events, and there are some gamma rays produced further down the decay chain. Both neutrons and gamma are not so easily shielded against but the intensity is fairly low.
The first decay product is U-234, which has a half-life of like 250K years, so the radiation levels from its decay (via whatever path), and its descendants in turn, will be pretty low.
Noel
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The first four decays in the chain are alpha decays, U234->Th230->Ra226->Rn222, then some beta decays start showing up. However a very small percentage of decays are spontaneous fissions which throw out neutrons. Also there are other radioactive isotope impurities in the PU238 as well which contribute beta and gamma decays. All in all Pu238 is by far the best isotope for RTGs from a standpoint of half-life, decay energy, and minimum shielding requirements. I hope Congress stops giving lip service to starting up Pu238 production and actually funds it for once.
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The first four decays in the chain are alpha decays, U234->Th230->Ra226->Rn222 ... However a very small percentage of decays are spontaneous fissions which throw out neutrons.
Right, but my point (which I guess I didn't make clearly enough) was that the 250K-year half life of U-234 applies to all the decay modes, including the spontaneous fission one.
(I.e., to belabour the point to death, if x% of U-234 decays are via the fission mode instead of the alpha mode, the half-life of that x% fraction of the U-234 is also 250K-years.)
And with that long a half-life (about 3K times as long as that of the Pu-238), the radiation levels from the decay of U-234 will be 'pretty low' (1/3K that of the Pu-238, for all decay modes together, so the fission one will be much smaller than that).
I hope Congress stops giving lip service to starting up Pu238 production and actually funds it for once.
Amen to that!
Although I read somewhere that NASA still has enough for a decade or so, at the moment, though...
Noel
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I was actually referring to the spontaneous fissions of the Pu238. The fraction of decays that are spontaneous fission is very small, but with something like 2 million billion decays a second in the MMRTG it doesn't take much.
Pu238 is just wonderful stuff, 1/2 watt per gram, 88 yr half-life, incredibly easy to shield.
Now with MSL launched there is something like 16.8 kg of Pu238 left, which is only about half what the Cassini probe used. I believe under the current Pu238 supply issues no probe or spacecraft proposal launching past 2018 will be accepted if it requires Pu238. The ASRG can extend the limited supply of Pu238, but with moving parts it's going to be considered risky for very long duration missions. The Pu238 shortage is definitely crimping future missions from here on out.
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Is Pu238 the same stuff that is used in nuclear bombs? If yes, then there should be nearly unlimited supply of Pu238, by disassembling and recycling old bombs.
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Is Pu238 the same stuff that is used in nuclear bombs? If yes, then there should be nearly unlimited supply of Pu238, by disassembling and recycling old bombs.
No. That's 239 or 241.
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No. bombs use Pu239. not the same at all. Weapons grade plutonium is 93%-98% Pu239, most of the rest is Pu240, and a few tenths of a percent of Pu241. Although Pu238 has a bare critical mass of around 15kg it's essentially impossible to make a bomb with it because of the enormous amount of heat being generated. It would just melt from it's own decay heat. Pu238 is actually one of the most effective ways of denaturing Plutonium to render it unusable for weapons.
Also you want relatively pure Pu238 to keep radiation other than Alpha decays to a minimum. Pu238 is made by putting Neptunium 237 targets inside a reactor and bombarding them with neutrons. It used to be relatively 'cheap' because it could be made in all the bomb grade plutonium production reactors used for making weapons material in the US and Soviet Union. But after the end of the cold war those reactor facilities were shut down.
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Well, if it is so easy to produce and there is a good market demand i am sure someone (the Chinese) will start producing it and selling it. It's another question if the US would want to buy it from the Chinese :)
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The Chinese are pursuing nuclear power and nuclear research very aggressively while it stagnates in the west. It wouldn't surprise me if the US is buying reactors from China in 10-20 years. I expect they very much will set up Pu238 production at some point. I have no idea if they would be willing to sell it though.
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I was actually referring to the spontaneous fissions of the Pu238.
Ah, got it now. Sorry!
there is something like 16.8 kg of Pu238 left
All busily decaying with a half-life of 88 years!! Athough I guess that's long enough that not that much will have decayed before it is 'used' in RTG's.
The Pu238 shortage is definitely crimping future missions from here on out.
Yeah, wasn't thinking about the planning impact - without a guaranteed supply, one can't really rely on it when planning, I can see.
Noel
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How does the Rover Break? What keeps it from rolling away on a slope?
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All that you ever wanted to know about Pu-238 and its use in American spacecraft:
http://www.nap.edu/openbook.php?record_id=12653&page=R1
(also attached below)
I was involved in that a few years ago. The report's conclusions are still valid.
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If you ever were interested in most trades in MSL mission design, here is a 256-page, 20MB Mission Concept Review doc back from 2003 :
http://web.archive.org/web/20061007133043/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38317/1/03-2974.pdf
And here is the 2001 Science definition team report on its science goals, from which mission reqts were derived.
http://www.spaceref.com/docs/mars/10.11.01.mars.sci.def.team.pdf
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Thanks Blackstar and Savuporo. Wonderful resources :)
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Repost:
How does the Rover Break? What keeps it from rolling away on a slope?
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Not an expert, but I believe the gearing coupled with the resistance of the electric motor itself is ample friction to act as a brake. Sojourner used a 2000:1 gearing system and whilst I don't know what is used on Curiosity, it is evolved from the same basic system so is probably also a very high ratio.
Interestingly, Curiosity has a means of disengaging the drive system to allow the wheel to rotate freely. This means that if it suffers a failed wheel, like Spirit, it won't have to drag it along behind it. This bodes well for a long and productive roving mission.
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Thank you!!
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Not an expert, but I believe the gearing coupled with the resistance of the electric motor itself is ample friction to act as a brake.
Even if it weren't any regular H-bridge driving the motor allows "shorting" of the leads which puts a hard brake on the motors.
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Q1: What kind of multitasking is the rover capable of?
For example, while the SAM is analyzing a sample (for up to 3 hours), can the arm move away and let the APXS make an analysis on the ground while at the same time a new weather reading is made? Can SAM work while it's driving? Or is it strictly one thing at a time.
Can its Mastcams film (10 fps/s, 3D, I read) the arm while it is moving?
I can imagine that the electric output is a restraint, but also that they are very careful.
Q2: What is the energy consumption of different operations?
What is the rank of these operations in terms of energy consumption:
-Driving X feet.
-The complete operation of the arm to take a drilled sample.
-Radio transmissions.
-The scientific instruments performing each one full analysis.
Does any one type of operation stand out as a real energy hog?
As for the computer discussion here recently, I guess that they have no need for more computational power. And also that they need to save energy, they might for example have preferred a 133 MHz over a 200 for that reason.
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What is that concave feature on the ridge of mount Sharp (or on the mound), which I've circled?
The enclosed image cut comes from the panorama here:
http://www.planetary.org/blogs/emily-lakdawalla/2012/08171906.html
Also, I wonder if there is any panorama around with a bar at the bottom which indicates the direction in degrees in which one is viewing? I'd like to pin point where in the panorama above, for example, Glenelg is located. I would now guess that it's slightly to the left of where the shadow of the mastcam points.
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What is that concave feature on the ridge of mount Sharp (or on the mound), which I've circled?
The enclosed image cut comes from the panorama here:
http://www.planetary.org/blogs/emily-lakdawalla/2012/08171906.html
Also, I wonder if there is any panorama around with a bar at the bottom which indicates the direction in degrees in which one is viewing? I'd like to pin point where in the panorama above, for example, Glenelg is located. I would now guess that it's slightly to the left of where the shadow of the mastcam points.
It's just the effect of the blurry background. The whole top of the ridge is fuzzy, and it's only because you have a high contrast area with that dark area (likely due to a depression) that it shows up that way
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It's just the effect of the blurry background. The whole top of the ridge is fuzzy, and it's only because you have a high contrast area with that dark area (likely due to a depression) that it shows up that way
Actually, it's a piece of the rover that was photoshopped out. The mountain in that stitch was from the early hazcam shot. Description here: http://www.planetary.org/blogs/emily-lakdawalla/2012/08171906.html
Damien Bouic has stepped into the breach, doing his best with the only photo we have that reaches the mountaintop: the one taken by the rover's forward Hazard Avoidance camera on the day of the landing. It's a wide-angle, fisheye camera, so the view is pretty low-resolution, and there's a divot at the right side where a piece of Curiosity obstructed the view.
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Sorry for not reading all previous 14 pages,but I have a question:
why is rover white?? Last thing we need on Mars is COLD, so why didn't they paint the rover black, to gain some °C without needing electricity?
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You are correct that a darker colour absorbs heat more easily, but it works both ways and it will also lose heat more quickly.
A lighter colour both absorbs and emits less heat over the course of a day, which makes thermal regulation of the rover easier.
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Sorry for not reading all previous 14 pages,but I have a question:
why is rover white?? Last thing we need on Mars is COLD, so why didn't they paint the rover black, to gain some °C without needing electricity?
Overheating is as much of a danger as freezing to death - they have to design not only for the coldest temperatures the rover will encounter in the dead of winter and dark of night (when the sun is no help anyways) but also for the hottest temperatures it will encounter at high noon in the summer.
It's often technologically easier to add heat than it is to get rid of it, especially when you already have a 2 kW heater for a derriere. While parts that sit outside the body like the wheel motors, and mast and robotic arm instruments require electric heaters, the rover body itself is plumbed into the cooling loop for the RTG and can adjust the flow of heat into the body as necessary. It's practically free heat.
Bonus question - What color are the robotic arm joints and turret and wheel motor covers on MSL?
Hint:
http://photojournal.jpl.nasa.gov/catalog/PIA15277
(I can't confirm authoritatively that the different thermal control requirements are the reason, but I strongly suspect so).
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Question: Since MSL's RAD instrument has revealed that surface radiation levels at Gale crater are comparable to those on the ISS in Earth orbit, could Lichens from Earth survive (and produce oxygen) there? I know they survive freezing here on Earth but a cold winter's night on Mars would be much colder, even in the Martian tropics.
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Question: Since MSL's RAD instrument has revealed that surface radiation levels at Gale crater are comparable to those on the ISS in Earth orbit, could Lichens from Earth survive (and produce oxygen) there? I know they survive freezing here on Earth but a cold winter's night on Mars would be much colder, even in the Martian tropics.
It might be too dry. The extreme aridity and negligible atmospheric pressure would desiccate any surface organism not to mention UV and perchlorates.
But it is an intriguing question. I think a good place to start might be the Dry Valleys of Antarctica or the Atacama Desert. Lichens barely survive in the Dry Valleys and grow very slowly (on the order of .01 to .005 mm/year). However Mars is a much tougher environment.
Were thinking in terms of terraforming? Extreme patience would be required using lichen... :)
I believe that lichen can even dissolve rock (with an organic acid) and contribute to soil growth but even on Earth this is very slow.
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Question: Since MSL's RAD instrument has revealed that surface radiation levels at Gale crater are comparable to those on the ISS in Earth orbit, could Lichens from Earth survive (and produce oxygen) there? I know they survive freezing here on Earth but a cold winter's night on Mars would be much colder, even in the Martian tropics.
Researchers in Europe have studied this. The lichen Xanthoria elegans has been taken to the ISS and left outside in the vacuum of space and it still photosynthesized when it was brought back and warmed and wetted.
http://en.wikipedia.org/wiki/Xanthoria_elegans
They also had this lichen in a chamber simulating Mars conditions and found that it photosynthesized, albeit for a couple of days. It was determined that Mars is too dry for this lichen.
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Xanthoria elegans survived for 4 days in Martian conditions. Here is the reference:
De Vera, Jean-Pierre. (2012) Lichens as survivors in space and on Mars. Fungal Ecology 5:472-479
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Space Science Reviews papers describing the MSL instruments and mission are currently free to download from http://link.springer.com/journal/11214/170/1/page/1 (via Ryan Anderson's blog (http://blogs.agu.org/martianchronicles/2012/11/19/msl-instrument-papers-available/))
Putting this in Q&A since it contains a lot of A ;)
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Possibly big news from Mars:
http://m.npr.org/news/front/165513016
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What would the payload be if MSL were to land at an area that was -7km MOLA?
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I know this is an old thread but I've got a question that has been "urking" me...
So prior to parachute deployment, MSL ejected six tungsten weights (each 25kg) as a ballast. My question is why six? Why not one 150 kg ballast?
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I know this is an old thread but I've got a question that has been "urking" me...
So prior to parachute deployment, MSL ejected six tungsten weights (each 25kg) as a ballast. My question is why six? Why not one 150 kg ballast?
Bring the the cg to the center of the vehicle and easier to attach to the aeroshell
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Bring the the cg to the center of the vehicle and easier to attach to the aeroshell
Six tungsten ballasts were easier to attach to the aeroshell than one ballast?
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Bring the the cg to the center of the vehicle and easier to attach to the aeroshell
Six tungsten ballasts were easier to attach to the aeroshell than one ballast?
The aeroshell is composite.
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Bring the the cg to the center of the vehicle and easier to attach to the aeroshell
Six tungsten ballasts were easier to attach to the aeroshell than one ballast?
The aeroshell is composite.
Volume, local attachments strength or balance issues?
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Bring the the cg to the center of the vehicle and easier to attach to the aeroshell
Six tungsten ballasts were easier to attach to the aeroshell than one ballast?
Yes, if you want to be able to eject them cleanly and maintain the desired CG.
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Imagine being on a falling hexagon and throwing a 150 kg weight overboard.
Now imagine being on the same falling hexagon and throwing (6) 25 weights overboard in a hexagonal pattern.
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Imagine being on a falling hexagon and throwing a 150 kg weight overboard.
Now imagine being on the same falling hexagon and throwing (6) 25 weights overboard in a hexagonal pattern.
I'm imagining... were the ballasts ejected all at the same time?
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Imagine being on a falling hexagon and throwing a 150 kg weight overboard.
Now imagine being on the same falling hexagon and throwing (6) 25 weights overboard in a hexagonal pattern.
I'm imagining... were the ballasts ejected all at the same time?
Yes
The spacecraft was balanced for the cruise. It spun for stability.
Since the entry vehicle was going to use a lifting entry, it needed to have an offset cg and so weights were ejected before entry. However, JPL wanted to have a balanced vehicle for parachute deployment, so after entry more weights were ejected to bring the vehicle back into balance.
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Yes
The spacecraft was balanced for the cruise. It spun for stability.
Since the entry vehicle was going to use a lifting entry, it needed to have an offset cg and so weights were ejected before entry. However, JPL wanted to have a balanced vehicle for parachute deployment, so after entry more weights were ejected to bring the vehicle back into balance.
I get all that but I'm still having trouble understanding why 6 ballasts were needed...
Thanks for all the replies BTW.
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Yes
The spacecraft was balanced for the cruise. It spun for stability.
Since the entry vehicle was going to use a lifting entry, it needed to have an offset cg and so weights were ejected before entry. However, JPL wanted to have a balanced vehicle for parachute deployment, so after entry more weights were ejected to bring the vehicle back into balance.
I get all that but I'm still having trouble understanding why 6 ballasts were needed...
Thanks for all the replies BTW.
To spread out the mass distribution and the attachment loading.
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To spread out the mass distribution and the attachment loading.
Ok, thanks.
Is there an image showing the two sets of ballasts by any chance? I searched but couldn't find any... :-\