Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

RGClark · 2013-04-24 12:11:18

RGClark wrote:

I missed this story when it came out last month:
Weather On Mars Surprisingly Warm, Curiosity Rover Finds.
by SPACE.com Staff
Date: 01 October 2012 Time: 07:00 AM ET
"If this warm trend carries on into summer, we might even be able to foresee temperatures in the 20s [Celsius], and that would be really exciting from a habitability point of view," Gómez said. "In the daytimes, we could see temperatures high enough for liquid water on a regular basis. But it’s too soon to tell whether that will happen or whether these warm temperatures are just a blip.”
http://www.space.com/17828-mars-weather … overy.html

Bob Clark

The Winds Still Blow in Thin but Active Martian Atmosphere.

http://www.americaspace.com/?p=33999&cpage=1

It is notable that daytime ground temperatures are above the air temperatures. Eyeballing the ground temperature plot, I estimate the highest ground temperature reached as about 15 C, about 60 F. Depending on the amount of water vapor in the air near the surface this could allow small amounts of water to condense to liquid for short periods.
It would be interesting to find out if the relative humidity would allow water to condense on the surface in the thin Martian atmosphere.

Bob Clark

RGClark · 2013-04-24 12:13:37

SwRI study finds liquid water flowing above and below frozen Alaskan sand dunes, hints of a wetter Mars.
San Antonio TX (SPX) Apr 01, 2013

Recent measurements of air temperature and pressure recorded by the Mars Science Laboratory on the Curiosity Rover, which landed in Gale Crater last August, suggest that liquid water potentially would be stable there during the warmest portion of each day.
http://www.marsdaily.com/reports/SwRI_s … s_999.html

Bob Clark

Midoshi · 2013-05-03 18:18:44

Yesterday I attended a seminar given by Don Hassler, the PI for the RAD instrument on MSL. The topic was the radiation flux observed during cruise from Earth to Mars, and what conditions have been like on the Martian surface.

The fairly constant background of Galactic Cosmic Radiation (GCR) dominated the cruise dose, though he pointed out that if you had a big enough solar flare it could have delivered a comparable dose (they did in fact see 5 moderate flares during cruise, but they contributed only ~5% of the total amount of radiation).

Being inside the MSL capsule in cruise provided a significant amount of shielding, comparable to that on the ISS (something on the order of 20g/cm2). About 500 mSv was accumulated during cruise, which would be roughly half an astronaut's typical career allowance. Don mentioned that a manned cruise would be designed to be shorter for than a robotic mission, and pointed out that shielding around sleeping quarters using drinking water/propellant tanks could significantly reduce the amount of radiation received.

On the Martian surface RAD has seen radiation fluxes values ~1/2 of what it did in cruise. This is basically because half the sky is blocked by the planet. The thin Martian atmosphere itself offers a level of protection comparable to the MSL capsule structure.

louis · 2013-05-04 14:59:42

Midoshi wrote:

Yesterday I attended a seminar given by Don Hassler, the PI for the RAD instrument on MSL. The topic was the radiation flux observed during cruise from Earth to Mars, and what conditions have been like on the Martian surface.
The fairly constant background of Galactic Cosmic Radiation (GCR) dominated the cruise dose, though he pointed out that if you had a big enough solar flare it could have delivered a comparable dose (they did in fact see 5 moderate flares during cruise, but they contributed only ~5% of the total amount of radiation).
Being inside the MSL capsule in cruise provided a significant amount of shielding, comparable to that on the ISS (something on the order of 20g/cm2). About 500 mSv was accumulated during cruise, which would be roughly half an astronaut's typical career allowance. Don mentioned that a manned cruise would be designed to be shorter for than a robotic mission, and pointed out that shielding around sleeping quarters using drinking water/propellant tanks could significantly reduce the amount of radiation received.
On the Martian surface RAD has seen radiation fluxes values ~1/2 of what it did in cruise. This is basically because half the sky is blocked by the planet. The thin Martian atmosphere itself offers a level of protection comparable to the MSL capsule structure.

Thanks for that summary of the info gathered. V. interesting. Confirms my general impression. Would you agree there is really more of a problem on the Mars surface, in terms of explorers being exposed on a daily basis. But that too can be taken care of through shielding of habitats and vehicles.

I think the real health threat is much more the effects of gravity. It's a bit of a roll of the dice to assume that being in third gravity will protect the first settlers.

Midoshi · 2013-05-04 16:12:03

louis wrote:

Thanks for that summary of the info gathered. V. interesting. Confirms my general impression. Would you agree there is really more of a problem on the Mars surface, in terms of explorers being exposed on a daily basis. But that too can be taken care of through shielding of habitats and vehicles.
I think the real health threat is much more the effects of gravity. It's a bit of a roll of the dice to assume that being in third gravity will protect the first settlers.

It depends on how long the mission is. The mission design for a "long" trip would have about 200 days of cruise to and from Mars, and 600 days on the surface in between (so ~1000 days total). All else equal between spacecraft and surface habitat conditions, the explorers are exposed to less radiation while on Mars, and wind up accumulating about as much radiation damage in cruise as during their time on Mars. On the other hand, if you're doing a longer tour on Mars (in the extreme case, a one-way trip), then the radiation received while on the planet will easily dominate the total dose. As you point out, a significant amount of that could be attenuated by intelligent shielding of living and working areas

louis · 2013-05-04 17:37:42

Midoshi wrote:

louis wrote:
Thanks for that summary of the info gathered. V. interesting. Confirms my general impression. Would you agree there is really more of a problem on the Mars surface, in terms of explorers being exposed on a daily basis. But that too can be taken care of through shielding of habitats and vehicles.
I think the real health threat is much more the effects of gravity. It's a bit of a roll of the dice to assume that being in third gravity will protect the first settlers.
It depends on how long the mission is. The mission design for a "long" trip would have about 200 days of cruise to and from Mars, and 600 days on the surface in between (so ~1000 days total). All else equal between spacecraft and surface habitat conditions, the explorers are exposed to less radiation while on Mars, and wind up accumulating about as much radiation damage in cruise as during their time on Mars. On the other hand, if you're doing a longer tour on Mars (in the extreme case, a one-way trip), then the radiation received while on the planet will easily dominate the total dose. As you point out, a significant amount of that could be attenuated by intelligent shielding of living and working areas

I think over the last few years I have come round to the view that a lot of outside activities can be carried out by robots. We have some incredibly sophisticated robots on Earth now - the only prob. is that they are very expensive, but that isn't really an issue with a multi billion dollar Mars mission. I think we should restrict to outside activity in space suits for humans to a few days in high summer on Mars when they might be able to wear light mittens with their finger pads exposed...That would be nice, if they could tell us how Mars feels when the temperatures are up to double figures celsius.

StarDreamer · 2013-05-04 18:11:58

louis wrote:

I think over the last few years I have come round to the view that a lot of outside activities can be carried out by robots. We have some incredibly sophisticated robots on Earth now - the only prob. is that they are very expensive, but that isn't really an issue with a multi billion dollar Mars mission. I think we should restrict to outside activity in space suits for humans to a few days in high summer on Mars when they might be able to wear light mittens with their finger pads exposed...That would be nice, if they could tell us how Mars feels when the temperatures are up to double figures celsius.

Um, wouldnt their blood boil in their capillaries? I think human body temperature is incompatible with such an environment.

louis · 2013-05-05 05:36:15

e

StarDreamer wrote:

louis wrote:
I think over the last few years I have come round to the view that a lot of outside activities can be carried out by robots. We have some incredibly sophisticated robots on Earth now - the only prob. is that they are very expensive, but that isn't really an issue with a multi billion dollar Mars mission. I think we should restrict to outside activity in space suits for humans to a few days in high summer on Mars when they might be able to wear light mittens with their finger pads exposed...That would be nice, if they could tell us how Mars feels when the temperatures are up to double figures celsius.
Um, wouldnt their blood boil in their capillaries? I think human body temperature is incompatible with such an environment.

I did read into that a while back. It's a lot less straighforward than appears at first sight. If you put a drop of blood, that might boil off (though we've seen water droplets on Mars). However, we don't have blood exposed in the human body like that.

I am afraid I don't have citations, but my recollection was that in warm weather (and it often gets well above 0 degrees celsius) there would be no problem with removing your gloves from a mechanical pressure suit for a few minutes. However, I am imagining some sort of specialist glove where you can open up the finger pads at will, so the Mars explorer can actually touch the planet - that would be a great moment!

The dangers of the low atmospheric pressure have also been exaggerated.

GW Johnson · 2013-05-05 13:24:08

Louis:

We've known since about 1960 that a vacuum-exposed hand takes about 20-30 minutes before tissue edema/swelling/incapacitation sets in. You could do this safely (in terms of vacuum injury) for maybe 10-20 minutes, even in deep space. That would be the unpressurized-glove incident in Capt. Kittinger's first extreme-altitude balloon jump (of two, both near 100,000 feet).

The only other sources of injury to an exposed hand on Mars (or in deep space) would be thermal injury (too hot or cold a surface to touch), and exposure to some chemically- or mechanically-dangerous material (same as here at home).

Thermally, too hot is about 105-110 F (near 40-42 C), and too cold depends upon a lot of circumstances. The maximum is said to be 115 F (about 45 C) for humans. There seems to be little or no danger associated with frozen products from ice cream trucks. Those freezers are usually in the range of -10 to -20 F (near -22 to -27 C).

I personally have handled dry ice barehanded for up to 7-10 seconds at a time, but only if it was wet with alcohol, at -110 F (-79C), but you cannot do that dry!!!! The moisture in your hands will immediately freeze to the dry ice if it is not wet with some liquid. Frostbite in a fraction of a second that way.

GW

JoshNH4H · 2013-05-06 12:42:08

It's probably worth noting that dry ice would be more effective at cooling your hand down to subzero temperatures because it sublimes and absorbs energy, whereas mars rocks would simply be very cold. However, I gather that there is sulfur trioxide in the martian soil in significant quantities, as well as perchlorates. Both of these are strong oxidizers. I can't speak to how much damage they would do, whether it be a lot or a little. In any case, I don't think that the usefulness of open gloves is very high relative to the risks/dangers and inconvenience, as well as the limits on activity of our Areonauts and colonists.

louis · 2013-05-06 16:47:05

GW Johnson wrote:

Louis:
We've known since about 1960 that a vacuum-exposed hand takes about 20-30 minutes before tissue edema/swelling/incapacitation sets in. You could do this safely (in terms of vacuum injury) for maybe 10-20 minutes, even in deep space. That would be the unpressurized-glove incident in Capt. Kittinger's first extreme-altitude balloon jump (of two, both near 100,000 feet).
The only other sources of injury to an exposed hand on Mars (or in deep space) would be thermal injury (too hot or cold a surface to touch), and exposure to some chemically- or mechanically-dangerous material (same as here at home).
Thermally, too hot is about 105-110 F (near 40-42 C), and too cold depends upon a lot of circumstances. The maximum is said to be 115 F (about 45 C) for humans. There seems to be little or no danger associated with frozen products from ice cream trucks. Those freezers are usually in the range of -10 to -20 F (near -22 to -27 C).
I personally have handled dry ice barehanded for up to 7-10 seconds at a time, but only if it was wet with alcohol, at -110 F (-79C), but you cannot do that dry!!!! The moisture in your hands will immediately freeze to the dry ice if it is not wet with some liquid. Frostbite in a fraction of a second that way.
GW

Hi GW - Thanks for confirming my rather vague recollections of the science.

I do remember reading that humans can endure incredibly high temperatures as long as they are not being subject to direct rays on their skin.

There was horrible incident here recently where a young girl lost here stomach as a result of imbibing dry ice (it's been used as a drinks novelty in some bars - ludicrously).

GW Johnson · 2013-05-07 09:01:56

Some time in the mid-to-late 1950's, there was a series of high-temperature experiments done at one of the New Mexico air force bases. I don't remember which base. These experiments exposed volunteers to oven temperatures, but at extreme low humidity (the New Mexico desert). The final experiment was somewhere around 1/2 or 3/4 of an hour at 350 F. The men were fine, but a tray of raw cookies that went in with them burned.

I myself have worked for up to an hour in-and-out of jet blast from various things, in much higher humidity. Temperatures were quite variable, but peaking around 300 F. Not a whole-body immersion, either, just blast on one side or the other. Sniffing for unburned fuel traces to diagnose combustion problems. In the case of a turboprop running on biodiesel blend, I could identify the source of the biodiesel by its burnt smell. It was actually quite funny and a lot of fun to do.

Biodiesel from waste cooking grease smells like french fries cooking. Biodiesel from animal tallow smells like barbecue cooking.

GW

RGClark · 2013-05-27 22:42:36

Midoshi wrote:

Yesterday I attended a seminar given by Don Hassler, the PI for the RAD instrument on MSL. The topic was the radiation flux observed during cruise from Earth to Mars, and what conditions have been like on the Martian surface.
The fairly constant background of Galactic Cosmic Radiation (GCR) dominated the cruise dose, though he pointed out that if you had a big enough solar flare it could have delivered a comparable dose (they did in fact see 5 moderate flares during cruise, but they contributed only ~5% of the total amount of radiation).
Being inside the MSL capsule in cruise provided a significant amount of shielding, comparable to that on the ISS (something on the order of 20g/cm2). About 500 mSv was accumulated during cruise, which would be roughly half an astronaut's typical career allowance. Don mentioned that a manned cruise would be designed to be shorter for than a robotic mission, and pointed out that shielding around sleeping quarters using drinking water/propellant tanks could significantly reduce the amount of radiation received.
On the Martian surface RAD has seen radiation fluxes values ~1/2 of what it did in cruise. This is basically because half the sky is blocked by the planet. The thin Martian atmosphere itself offers a level of protection comparable to the MSL capsule structure.

Robert Zubrin has maintained the radiation problem has been overblown. Does this MSL evidence support that view?

Bob Clark

Midoshi · 2013-05-28 00:27:18

RGClark wrote:

Robert Zubrin has maintained the radiation problem has been overblown. Does this MSL evidence support that view?
Bob Clark

The main problem with radiation is the uncertainty in what constitutes an acceptable dosage, with a subsidiary question of how to provide shielding adequate to achieve that while maintaining all other engineering constraints (mass economy, structural strength, etc.). Given this uncertainty, many people either underestimate or overestimate it, brushing it aside or claiming it is a showstopper. The impression I got from Don's presentation and the following Q&A session was that we can probably deal with the radiation. However, we are still at the stage where we need to better characterize it and it's effect on humans before we actually start designing a flight-worthy system for dealing with it during interplanetary cruise.

GW Johnson · 2013-05-28 13:55:11

I would think that, once on Mars, you simply put a lot of regolith (multiple meters) on the roof over your head, thus providing excellent shielding. This would take care of both the slow drizzle of cosmic rays, and the brief flashes of solar flares. That lets you maximize time outside doing good things, without overdosing on radiation so soon.

For the cruises to and from, it appears that the capsule or habitat structures might provide a bit of shielding. However, whether you do a closed or open life support system, water and wastewater will be involved. The "killer" in cruise is the brief flash of a solar flare. 20 cm of water will shield those solar flare events just fine, and cut the cosmic rays by about half.

So, pick a space to be the shelter, and wrap those water and waste water tanks (that you must have, anyway) about it. If you were a smart ship designer, the radiation shelter would be the flight control deck or space. That way, critical maneuvers could be flown regardless of the solar weather.

Midoshi is right: the biggest factor in this is the allowable dosage. Not everybody agrees. We have a standard that NASA uses for astronauts that is at least twice what is recommended for civilian adults. For children, the recommendations are even less. But there is little agreement among the various countries and groups-within-countries.

I think we could use the NASA astronaut standards with reasonable confidence for explorers sent to Mars and then returning. The doses are gender and age dependent. For a colony or one-way mission, we'd have to come up with dose standards for children. Don't have any now.

GW

Vincent · 2013-07-05 08:02:09

Test

http://www.flickr.com/photos/11627092@N06/9216615860/

Vincent · 2013-07-05 08:06:05

Test

http://www.flickr.com/photos/11627092@N06/9216615860/

Vincent · 2013-07-05 08:26:15

We always love to see the image. A link that works will do. First the new name for "true color" is "raw color." Who would have thunk it. Just load a camera on board and take the picture. It's not magic and not complicated and it aint red. I said that 30 years ago. I post a link below for those who were not born yet when the fight began.

Also we should talk about the apparent lack of visible fossils. More were seen along the track of Opportunity than here with Curiosity.

My theory goes like this. The window for development was small. I believe and propose that this area was hit by a large impact that destroyed any possibility of surface observation. Extreme heat and impact process compacted and or destroyed any fossils of complex development. This occurred near the end of Martian development. Any residual development was microscopic and can only be observed in this way.

A link to the way we were told Mars looked like in 1976....

http://www.flickr.com/photos/11627092@N06/9213934767/

Vincent · 2013-07-05 09:34:02

I think we should produce at least one fossil from Miridiani. This is a berry on a stem. If you notice at the Curiosity site, that the concretions are irregular, as they should be. The berries are perfect sphericals on stems.
Keep in mind this is a nonimpact zone...

A cross eyed 3D of the stemmed berries.

berry stem two honkers by dfrank39, on Flickr

Fossilized stemmed Berries.

mama and papa by dfrank39, on Flickr

If you want a fossil hunters guide go here...

http://www.shultslaboratories.com/AFHG2MPR.htm

Last edited by Vincent (2013-07-22 10:01:40)

Vincent · 2013-07-26 08:49:48

This image was posted in the weather thread in "Mars Water."

Here: http://newmars.com/forums/viewtopic.php … 48#p116748

You can go there for theory. Otherwise it is one of the best images from Curiosity. It is witness to the fact, " we are on the road again"

0343MR1388000000E1_DXXX by dfrank39, on Flickr

http://www.youtube.com/watch?v=Gdlyi5mckg0

Vincent

Last edited by Vincent (2013-07-26 08:59:40)

Vincent · 2013-08-01 10:09:47

A great image from Curiosity!!!

If nothing is there that would create a biological conversation, they will expand. Fist, it was grayscale jpeg haze, now this....

0346MR1408004000I1_DXXX by dfrank39, on Flickr

Vincent · 2013-11-29 12:32:10

Curtiosity has an elsectrical feedback loop. Static electrisity and the Hendenburg...

http://www.youtube.com/watch?v=CgWHbpMVQ1U

GW Johnson · 2013-11-30 10:20:38

It's been found that the Hindenburg would have crashed and burned even if she had been filled with helium. The hydrogen just made the fire brighter. The real fire was her doped skins which were actually a pyrotechnic material. The dope was nitrate base (well known, even infamous, for being extremely flammable) with a pigment that amounted to a weak thermite explosive (aluminum and iron oxide, but at the wrong ratio to be fully explosive). These skins were not electrically grounded to the aluminum frame, allowing ignition by static electrical discharge. That information was in insurance records from 1937 kept secret by the zeppelin company. These were finally opened in the late 1990's, and more than one investigator has now seen them. They (the owners) knew then what caused the crash.

Static discharge (any friction source, not necessarily anything to do with the thunderstorm in the vicinity) started a skin fire on the upper aft fuselage near the base of the upper vertical fin. The heat from that fire burst the hydrogen envelopes inside, one-by-one, as the fire propagated forward around 20-to-30 m per second. The slow tail-first crash confirms the one-by-one envelope burst pattern moving forward. The two-digit burn rate in m/s confirms the fire was the skins, not the hydrogen. Pre-mixed hydrogen in air only burns about 1.3 m/s laminar flame speed at 1 atm pressures, and this wasn't pre-mixed, much less turbulent.

As for Curiosity, static discharges really derange electronics, often fatally. This has been known for a long time now. These discharges are quite common on structures immersed in dusty winds, sometimes at lightning strength. If these discharges cause surges that reach the electronics, then the rover is at risk. But, I'd have a hard time believing they didn't provide protection in their design. This isn't the first rover those guys have built. It's just the first nuclear-powered one.

GW

RGClark · 2013-11-30 15:54:21

Vincent wrote:

This image was posted in the weather thread in "Mars Water."
Here: http://newmars.com/forums/viewtopic.php … 48#p116748
You can go there for theory. Otherwise it is one of the best images from Curiosity. It is witness to the fact, " we are on the road again"
http://farm8.staticflickr.com/7288/9368745519_7a0b31fcd1.jpg
0343MR1388000000E1_DXXX by dfrank39, on Flickr

http://www.youtube.com/watch?v=Gdlyi5mckg0

Vincent

Are these the mountains Curiosity is headed to? I would like to see some measurements made when Curiosity is in the midst of this fog or haze.

Bob Clark

GW Johnson · 2013-12-21 10:39:21

Oops. Aluminum wheels may not have been the best choice for a long-life nuke rover. News stories today indicate unanticipated rates of wear attributed to rough ground.

Everybody who has ever hiked around in the mountains knows how rough that kind of ground can be. Not sure whether weight or cost drove them to aluminum wheels, but I'd bet that team is regretting that choice now.

GW

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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

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#208 2013-05-05 05:36:15

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