Has anyone any idea what kind of imaging system is being proposed for the MSL? Would it be the same or simiilar to the MER's, or as improved as the MER pancams are to those that were used on Pathfinder?

With a nuclear power source for the rover, and hopefully the mars telecoms orbiter in place the data rate and data volume could be phenomenal

Going on the recent news ( i LOVE looking at really old forum posts ) the answer involves any and all of the following words

Order of Magnitude

Can of Whoop Ass

Mike Malin

VIDEOS

Where did all my bandwidth go



Doug

The new bandwith that the MRO will transmit is between 1 to 30 MBits/sec depending upon to the Mars' atmosphere transparency between MRO and Earth. The improved transmission bandwith is based on new technology of utilizing the bandwith closer to the light.

Rodolfo

There was a lot on this at the recent LPSC:

http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1214.pdf
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1170.pdf
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1580.pdf

Forgive me for opening up an old post, but I am a little confused on how Mastcam can aquire both multi-spectral, aswell as natural color imaging all in the same package. How would this all work out when there is bayer filter limited to the visible spectrum and IR filters that move into the infrared part of the spectrum?. How could any narrowband information passing through the filter wheel be salvaged when the light also passes through a broadband bayer filter?. I emailed the MSSS guys about this but have not got a response back .

Thanks

http://www.unmannedspaceflight.com/index.p...amp;#entry91486

Thanks Doug .

remarkable ChemCam: http://www.youtube.com/watch?v=fEZ5dEi4oPo...feature=related

It's also reassuring that this rover will be able to defend itself if attacked.

One issue that just popped into my head (not sure if it's been mentioned before): MSL will survive for a long time, so there will probably be significant dust buildup on MastCam (and on the other cameras), just like with MER. Phoenix showed that a magnetic ring around a surface will prevent that surface from being covered with dust. Has any effort been put into such a system on MSL's camera lenses? Would it even be possible?

I'm unaware of any quantitative analysis of how much dust buildup there has been on Pancam; maybe others know more. I had thought the dust buildup was mostly on the hazcams, which are much closer to the ground.

As for Mastcam, the current fixed-focal-length systems have the lenses set quite far back inside the sunshades (if you look at http://www.msss.com/msl/mastcam/index.html the front element is at about the front of the lens barrel, color-coded red), so the path for dust is quite long. MAHLI, of course, has a movable cover.

The MER Navcam lenses (esp. Oppy's) have dust accumulations ranging from light to very heavy -- Oppy's are quite occluded on the right sides of the images. However, this isn't a result of general dust accumulation, it happened almost entirely during the global dust storm (which also deposited dust onto the "protected" optics of the mini-TES instruments on both MERs, enough that it might possibly render the devices useless).

I think there's a difference between designing optics to remain "as clean as possible" during normal accumulation cycles and designing dust-storm-proof optics. I'm positive that MSL's cameras are good for the former, but doubt they're designed to handle the latter.

-the other Doug

Quite right. Aren't they concerned enough to make a mechanism for removing dust from the lenses?
If I recall well, the Beagle 2 lander had a 'wiper' for each eye of its stereo imaging payload. Why on earth won't anyone consider such a thing?

Because the cameras aren't on Earth. Designing a mechanism that can survive for many years under martian conditions and not fail in some way that degrades imaging is not worth it, given the low chance of dust contamination as I have already described.

The cameras are normally stowed pointing down. Was there some period on MER when they were left pointing up?

What makes you assume no one has considered it. I would bet the farm that it's not only been considered, but looked at carefully, the risks studied, and a call made.

Doug

Spirit's cameras all remain in great health

Opportunity got a smattering in both Navcams and Pancam's. If you notice a lot of Pancam imaging with Opportunity is done with only one half, or 3/4s of the CCD, as one side got quite a smattering.

http://marsrovers.jpl.nasa.gov/gallery/all...nity_p1671.html is an example of the technique.

http://marsrovers.jpl.nasa.gov/gallery/all...CSP2629L4M1.JPG is a typical example of the obstruction


Doug

The contamination happened during the dust storm, didn't it? So it's not exactly 'buildup' so much as a 'smattering' as you put it.

Regardless, the contamination of Opportunity's optics remains distressing - I'm sure to the science team as well as the sightseers.

http://www.planetary.org/news/2007/0930_Ma...ate_Spirit.html

It looks like the effects of this contamination could easily be taken out with a proper flat field, and I'm a little surprised that they haven't done this.

That said, owing to the configuration of the Mastcam I think it will be far more resilient to this sort of problem.

There was never any serious consideration given to adding a cover mechanism to the Mastcam, and nothing I see in the Pancam data would justify the added cost, complexity, and risk. I wouldn't even know how to begin to implement a "wiper" that would work reliably under martian conditions, and some kind of roll of clear material that could be driven past the lens would be problematic for all kinds of reasons.

If you look closely at the comparison mosaic on that page, notice that while the corner darkening was removed with a new flatfield, the frames suffer from lowered contrast there. The dust particles are no longer just a nuisance in the way, they diffuse/diffract the light. The effect can be likened to Titan's haze but on a much different scale. A flatfield simply cannot remove that. Had the dust been deposited on the actual CCD the situation would probably have been different.

This is a question I've been wondering about too. Were the cameras left unstowed at some point, or did Oppy just happen to get smacked in the face with an unusually large pile of dust during the brief period when it was trying to do imaging one day?

--Emily

If by "flat field" you mean something that merely multiplies each pixel by a single number, I agree. But these sorts of stray/scattered light problems can be addressed with more sophisticated techniques, for example the way the NEAR images were recovered after the front elements were covered with monoprop burn products. See "Inflight Calibration of the NEAR Multispectral Imager II. Results from Eros Approach and Orbit" by Murchie et al in Icarus 155, 1. I'm not sure the MER images are bad enough to require that level of processing though.

First, a 'stowed' camera is still at risk on MER. There are no in-flight dust shields for Navcam, Pancam. Looking down avoids sedimentation of dust, but not turbulence. I think turbulence maybe was involved. Second, I don't think the camera bar has been left stowed at nadir in quite some time. Stowing the cameras now places them looking sorta down, sorta out, I think. The actuators were not designed for a 5 year mission, let alone one with Opportunity's current ambition. If they fail, they should fail where Navcam is still useful rather than contemplating the rover's navel, umm, deck.

I wouldn't even know how to begin to implement a "wiper" that would work reliably under martian conditions...

I recall reading that Viking had two methods to avoid dusty optics, a physical barrier which covered the 'slit' when the camera was in its 'rest' position as well as compressed air which could be used to blow off the optics. I would think the latter could be adapted to a wide variety of camera designs.

Don

"I would think the latter could be adapted to a wide variety of camera designs."

I think we need it for Spirit's solar panels now...

Phil

I'd be willing to bet that the tank to contain the gas would weigh more than an entire Mastcam camera head. Not really practical given the mass constraints.

the tank to contain the gas would weigh more than...

Perhaps, but I wonder what the Viking unit weighed? How much more compact cound a similar modern system be built? I imagine something like a soda charger cylinder filled with very clean compressed gas, perhaps giving puff(s) of gas upon demand. A magnetic 'ring' around the lens could also help. However this is dealt with, cameras for long term Mars surface missions will require more attention to the dust hazard as part of the design.


Don

Now that's a solution I've not seen mentioned before, and it might make a lot of sense.

What about holding the air in the bodywork itself?

Making the entire electronics box a pressurised body? Given that it has to travel thru a vaccum? How do you engineer in the insruments and their openings to the sample collection mechanisms. That's an epic engineering challenge right there.

For Mars the body wouldn't have to be at insane levels of pressure - just "enough" over the external ~1 kPa to provide a squirt of gas where and when you need it. I don't think the high pressure 20 MPa sort of structure you see on air tanks is at all necessary here.

Just to put this into perspective: the r/c model sub community regularly work with pressures up to ~50kPa and manage with commercial linkages/prop shafts, etc., penetrating the core electronics box without too many problems.

That said, this Giotto air puffer would seem to be a more practical solution. And it's even rocket-shaped!

Andy

You still have to render the entire box air tight. That means seals of every access panel, seals for every cable in, every cable out. That pressure is going to go up and down with thermal cycles. It might change the thermal properties of the box itself. Then you've got to have valves, flexible pipe work out the box, up the past and to the front of the lenses. Pipework that's going to bend with every camera movement. With all due respect, a $1.X billion dollar rover is just a tiny bit more complex than an R/C sub.

AND - at the end of all that - if you've got a CRT monitor or an old TV - go and blow on it. The dust doesn't move very much, if at all. I know - wind has cleared arrays etc before, but we don't know the mechanism by which that occurs, nor do we know the mechanism by which it sticks.

If we really really want to have dust-removal - the best way is with the thin-film technique I blogged about at Valencia '06. Tiny power, low mass, low complexity. Turn them on for a few seconds - dust gone. Gas tanks, wipers, rolls of film - they're all very heavy, complicated, and have their own failure modes.

DOug

Unfair! Any CRT being bombarded by electrons (and thereby charged) in a dry, dusty atmosphere is not quite in the same league as a glass lens sat in front of a passive CCD.

Personally I like the thin film concept (much better than abrasive wipers - though even one of those would be helping Spirit's solar panels right now), but I also like the home-engineering "what if...?" kind of discussions here. Hmmm...Blame it on a childhood filled with Meccano.

Andy

I wonder about maybe some kind of electrostatic "wiper" - maybe something to move across the lens while holding a charge. Might the dust adhere to something like that, or perhaps be repelled by it? Either way, it could get rid of dust. Possibly maybe. I'm afraid I've not got much experience with electrostatics.

There is also the issue of having to make sure that whatever pressurized gas you used didn't cause a residue to build up on the lens. The cure could be worse than the disease.

I don't recall this reference, could you point me at it again?

This is all getting pretty off-topic for MSL; the hardware is built and doesn't include any kind of active dust removal.

The thin-film technique is described here:

http://science.nasa.gov/headlines/y2006/19apr_dustbuster.htm

Bingo. That's it. The wires are so fine, I bet for a future design, one could put something like that over the front of a Mastcam like Hood. The wires would be totally out of focus and not noticeable ( like the heating element in a heated front windscreen).

It certainly beats wipers, rollers, blowers etc.

Doug

Cool, thanks! But I don't think this would work for a camera without a good bit of technology development, because it'd be very difficult to make the transparent material optically flat.

Just noticed

http://mars.jpl.nasa.gov/msl/spotlight/ima.../20081119_1.gif

It has four rear hazcams - two each side of the RTG. I wonder if it's the same at the front.

Perhaps, but isn't the reason because the RTG would block the view of 1 set of hazcams if mounted in the middle? Or maybe because the rover is just so big; hazards increase with size?

I think it's just that you can't put them where you would want to - because the RTG is there. Can't

What about a stationary brush placed somewhere reachable by the mastcam? The brush could be wiped by the back (or whatever) of the camera housing to brush off dust, and then the brush itself could be used to clean the lenses. We might be on Mars for 10 years (oh joy!), so some sort of cleaning mechanism would seem necessary...

On another subject, I was thinking to myself whether there is some sort of mastcam lens protection during landing. Caps or just turning the lenses towards an enclosed space? A lot of dust will swirl up.

Also, wouldn't it be great if the navcams were turned on during landing, taking a movie? Not just great, but helpful for analysing EDL. If they have caps on them during landing, maybe the caps could be made of transparent material, so some filming would still be possible despite the dust.

No hardware changes from the current design before launch.

We have MARDI doing a movie during descent, we don't need Navcams doing it - and they'll be pointing into the rover deck at that time anyway - along with MastCam I presume.

Doug

As I said earlier in this thread, the Mastcam lens is many inches inside its sunshade and could not be reached by any plausible brush.

As to the navcams imaging during EDL: of course Doug is right, the navcams and Mastcam are pointed down towards the deck when the RSM is stowed. I guess the hazcams are looking at the ground during descent but the hazcam frame rate is quite slow (remember DIMES from MER) so only a few images could be taken, whereas MARDI will be running at about 4 FPS.

Does this MARDI have a microphone, Mike?

Nope, no microphone on the MSL MARDI. You should note that while it shares a name with the instrument on PHX, it's a completely different electronic design and doesn't use the cellphone processor that made adding a microphone to the PHX design fairly straightforward.

You can't simply plug one in through the spare USB port?

Interesting comment about the Mastcams from Mike Ravine of MSSS over at http://nasawatch.com/archives/2009/11/avat...i.html#comments

Not entirely accurate is it? If the fixed focus stays - then one eye will be about 3.75x the res of Pancam, the other one, about 1.25x Pancam. But the more I think about it - the more the zoom descope hurts.

Doug, you're right about the resolution. What we are really losing with the zoom is the ability to capture the entire surroundings in color with a small number of frames. As is, we will have only hazcam/navcam monochrome images to do that. And of course there's the 10 fps capability, which is really not that interesting with a narrow FOV.