Spirit Mission 2009 and onward

[dragon04]

What do you mean by a crawler?

I would imagine the poster is talking about a tracked vehicle. One problem with tracked vehicles is that dust and dirt get up into the tracks themselves and the wheels and gears associated with the track. On a tracked vehicle here on Earth, that's easy to fix. A guy jumps out of the tank or whatever and cleans the tracks out.

Cant do that from a hundred million miles away. Tracked vehicles would be a bad idea for Mars if for no other reason than that. There's also no guarantee that a tracked rover wouldn't get stuck, either.

Secondly, tracked vehicles have more moving/working parts. More parts mean more potential failures. More potential failures mean more risk. Risk is bad when designing space missions. I would imagine that engineers try to keep vehicles as simple as possible to reduce risk as much as possible.

 

[MeteorWayne]

Possibly, but I just want to be sure before I try and answer the question

 

[centsworth_II]

Even with my primative Adobe Photoshop CS3...

There's no chance that your "primitive" program is misleading you with low fidelity?

Texture aside, that "pile" has what may be impossibly steep sides and pointy peak for a pile of dust or sand.

edit: Then there's the possibility of a dust-covered rock.

 

[cello]

What do you mean by a crawler?

I would imagine the poster is talking about a tracked vehicle.

That's exactly what I meant. Tracked vehicle, vehicle that runs on tracks, not wheels. Like some tracked tractors or tank or typical snowmobile does. (Don’t know, why crawler was first term in my mind. English is not my first and even not a second language. Sorry )

So, first, tracked design is more complex and not as reliable. Isn’t it? Then we have potential dust problem with tracked design. Then, like we saw in some demos, design of independent wheels has ability to move over some obstacles (not big rocks). Tracks would not.

All the vehicles ever driven on the Moon or Mars has more or less similar wheel design. What alternatives has been considered and why the one is the best?

 

[MeteorWayne]

No apologies needed for the choice of word, I just wanted to be sure what you were talking about.

My guess is the main answer is the one most common in spacecraft to other worlds....weight. (or mass)

What is a tracked vehicle but a wheeled vehicle with heavy duty tracks covering the wheels? So you bring up the track, but you then have to eliminate that same amount of weight in scientific instruments from the vehicle to get it there.

After a while, you don't have enough instruments left to make the trip worthwhile.

 

[wtrix]

Why not tracks?

1. Tracks add weight. Although some weight is saved from eliminating the wheel steering mechanisms and motors, the net is still more
2. Tracks add friction requiring more energy to move less
3. Tracks lead dirt between themselves and the wheels which is not an issue if you have 1500 hp engine like in M1a2 Abrams tank, but which is a big issue in low powered electric robot rovers
4. Every tracked vehicle can throw the trakcs and ultimately will
5. All tracks break ultimately. Linked ones from non-lubricated friction and elastic ones from friction against surface+wheels and bending

And last, but not least - by design those rovers shall be dead for more than four years now. Every day this far has been a gift.

 

[3488]

Why not tracks?

1. Tracks add weight. Although some weight is saved from eliminating the wheel steering mechanisms and motors, the net is still more
2. Tracks add friction requiring more energy to move less
3. Tracks lead dirt between themselves and the wheels which is not an issue if you have 1500 hp engine like in M1a2 Abrams tank, but which is a big issue in low powered electric robot rovers
4. Every tracked vehicle can throw the trakcs and ultimately will
5. All tracks break ultimately. Linked ones from non-lubricated friction and elastic ones from friction against surface+wheels and bending

And last, but not least - by design those rovers shall be dead for more than four years now. Every day this far has been a gift.

Hi wtrix, I agree, tracks would only add mass & as Wayne said earlier, which piece of scientific payload are you going to sacrifice to keep the mass down?

Spiked wheels are better, like those employed by the MERs & the Pathfinder Sojourner Rover in 1997 & really lets face it have worked extremely well. The trick in future will be to try & understand the forward terrain through the images, though that is difficult. Dust dunes are easy enough to see & understand, but this dust trap was not immediately obvious as to me it looked like fairly sturdy ground, until it started to churn up, by which time it was too late.

A few nice recent mugshots.

MER A Spirit spies high altitude clouds during dusk. Sol 1,951.

Sol 1,955 looking towards Von Braun, hopefully Spirit will make it there.

Sol 1,957 Sun setting. There appears to be a hint of a martian sun pillar (not meaning the blooming effect on the CCDs of the Sun).

Sol 1,957 shortly after the above image just after sun set.

Sol 1,957 possibly considerably after the previous one, much deeper into twilight, signal to noise ratio has deteriorated, due to the much lower light levels, showing hot pixels & cosmic ray strikes, but is still a nice image, clearly showing how the light has diminished, how the glow in the sky has shrunk & lifted due to the sun being lower below the horizon.

Andrew Brown.

 

[Par72]

Andrew, are those meteorites in the last picture?

 

[3488]

Andrew, are those meteorites in the last picture?

Hi Par 72,

My gut feeling is that they are cosmic ray strikes on the CCD, though of course evening shooting stars cannot be ruled out & when that image was taken, it was getting quite dark (shame they no longer put LMST Local Mars Standard Time, on the image info).

Perhaps this is a good one for Wayne??

Almost certainly at least one shooting star has been seen from the martian surface, that was with Spirit way back on Sol 63. Dawn twilight.

This could have been part of a meteor shower whose parent body is Comet 114P/Wiseman-Skiff.

Because the radiant is in the constellation Cepheus, this meteor shower could be called the
Martian "Cepheids", as the radiant for this suspected Martian Meteor Shower is in Cepheus. The timing is perfect, as this was at the peak of that suspected meteor shower & the direction of the streak, also points towards Cepheus, although of course the image does not reveal the direction of travel of the streak.

There is much more about this on the Astronomy from Mars thread in SS&A.

IIRC, the same rules apply, that on Mars as on Earth, more shooting stars are expected before dawn, as the AM side of the planet faces in the direction of travel. The PM side is looking backwards, so any bolides on the PM side would have to be travelling faster than the planet.

Wayne will know much more for sure.

Andrew Brown.

 

[Par72]

Thank you for the good answer Andrew. Your work and knowledge have been an integral part of this board for many years. Thanks again.

 

[3488]

Thank you Par72 for your considerate response. It is very much appreciated.

Hi all,
MER A Spirit on Sol 1,994 carried out an interesting illumination experiment with the NavCam, taking mugshots under differing illumination. The information will be very useful in deducing textures, assistinbg in future driving strategies & scientific research into the processes that have helped shaped this area, etc.

MER A Spirit has also imaged here underside again.

Sol 1,990. Microscopic Imager views underside of Spirit.

Andrew Brown.

 

[3488]

MER A Spirit reaches 2,000 Sols on Mars today.

MER A Spirit has survived so far nearly 22.25 times the expected mission duration.

A nice Sol 2,000 dusk.

Alo MER A Spirit has continued the differing illumination experiment with the NavCam.

Von Braun & Goddard under a low morning sun. Sol 2,000.

Von Braun & Goddard under a high sun, near Midsol. Sol 2,000.

Von Braun & Goddard under a low sun just before sunset. Sol 2,000.

Von Braun & Goddard in dusk after sunset. The low light levels allow for a higher noise to signal ratio, hense the spots. Sol 2,000.

Andrew Brown.

 

[MeteorWayne]

Truly amazing Andrew. A 90 day mission that has lasted 2000 sols.

In future space history, people we be amazed that the little critters lasted that long.

In the here and now, all we can do is say thankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyouthankyou

 

[3488]

It is an amazing point to reach & surpass for sure. Lets see if she makes it to Sol 2,500????

As of Sol 2,001 the power output has dropped to 744 Watt Hours (which is still very healthy) as a regional dust storm passed by, but the arrays are still quite dust free, so when the TAU (Atmospheric Opacity) improves it should rise again. TAU has increased to 0.718.

Sol 2,003 view of a small patch of ground nearby. Shadows are indistinct due to the localised dust storm.

Sol 2,003 look across the plains of Gusev Crater, searching for dust devils & also note how the contrast is reduced due to the localised dust storm.

Sol 2,002 view of Von Braun & Goddard. The scene is a little subdued due to the regional dust storm.

Andrew Brown.

 

[bearack]

Andrew, the one stone in the above image really intrigues me. It looks like it is layered, maybe several basalt layers. Could this stone also be an indication what the surface was once wet or am I getting excited over nothing?

 

[3488]

Andrew, the one stone in the above image really intrigues me. It looks like it is layered, maybe several basalt layers. Could this stone also be an indication what the surface was once wet or am I getting excited over nothing?

Hi Tim,

Not at all my freind. Thank you very much for highlighting that rock. I was going to ask myself, but IMO it is one of three things.

1). It is exactly as you suggest, layered basalts. The lighter layers being possibly Andesitic types (silica rich but mineral poor) with more normal basalts being the darker layers.

or

2). It is layered basalt, dark layers with compressed hardened ash light layers.

or

3). It is ash layers that may have been deposited in water.

I hope Jon Clarke could give an opinion & see if I'm barking up the right tree at all. :lol: :lol: :lol:

Andrew Brown.

 

[centsworth_II]

Andrew, the one stone in the above image really intrigues me. It looks like it is layered...

Almost every stone in that image is layered. The whole of Home Plate is a stack of layered rock. Although the overall look of the stone is intriguing, I don't know if there is any reason to think that it is different from all the other remains of broken up Home Plate layered rock.

 

[3488]

Hi Centsworth,

I had not thought of it like that, though that seems plausible. I was looking at the rock in it's own context. True that Home Plate is also made of many shallow layers & Spirit has shown them in places to be alternate compressed ash, lava, compressed ash, lava etc.

So my option 2 could be the correct one. What grabbed my attenetion was that rock shows a coherent shape, i.e it's not ragged due to the layering, which made me think of my first option.

Perhaps Spirit when freed can go & take a quick closer look before pushing onto to Goddard & Von Braun?

Hi everyone,

MER A Spirit on Sol 2,006 has seen a large drop in power to 392 Watt hours from 744 Watt Hours as the southern portion of a localised dust storm passed over Gusev Crater. The arrays are still clean so power is expected to rise quickly once the storm passes.

Article Here & new Calypso Panorama

Below. Sol 2,006 RAT imprint during test of regolith rigidity.

Sol 2,006 Front HazCam image of RAT. Note how subdued the lighting is as the dust storm passes over.

Andrew Brown.

 

[MeteorWayne]

More Bad Week in Space:

Dust Storm Adds Urgency to Mars Rover Predicament
By Andrea Thompson
Senior Writer
posted: 26 August 2009
04:44 pm ET


Dust storms are currently stirring up the Martian skies in the region where NASA's Spirit rover is stuck in the sand. The swirling sands don't pose an immediate threat to Spirit, but they could create more urgency for the effort to free the mired rover if dust obscures her access to solar energy.


Spirit has been stuck in Martian dirt up to its hubcaps since May 6, when it became mired in a dirt patch (now called "Troy") while driving backward.


Engineers back on Earth have been using working replicas of the rover to test out ways to maneuver Spirit out of the sand trap.


So far, time has been on the team's time, as Spirit has plenty of energy ever since her solar arrays got cleaned off by winds a few months ago.


There's no immediate threat to Spirit's power levels from a darkened, dust-filled sky, as the rover has plenty of reserves and rover handlers are being conservative with their energy use, said project manager John Callas. But when the winds abate, they may have a problem, as the dust will then start falling back to the Martian surface.


"If the dust is raining out of the skies, it will build back up on the solar arrays," Callas said. This could become a problem during the next Martian winter, when the sun is low in the sky and generally making it difficult to keep power supplies up.

http://www.space.com/missionlaunches/09 ... storm.html

 

[3488]

Hi Wayne, I really hope the descending dust will not cause a huge problem. I just checked the Sol 2,009 panCam images of the Sun, & yes it is a little hazy still.

Also the Sol 2,009 NavCam imagery looking for dust devils out on the the plains of Gusev Crater, & yes, they too look a little subdued, though better than on Sols 2,007 & 2,008.

The new full colour pan is available here in hi res.

Please be warned it is 28 MB.

I will have a go at chopping it up into bite sized sections (still remember a_lost_packet doing likewise for me with the monster 64 MB Phoenix Mars Lander pan, I have still not forgotten that act of kindness & have those images safely backed up) & link them to this thread.

Large MER A Spirit Calypso PAN 28 MB

Andrew Brown.

 

[3488]

Four Crops from the large recent Calypso Pan.

Von Braun & Goddard.

Sulphate Rich regolith that trapped Spirit.

Layering on the side of Home Plate.

Looking across to Thera Crater peering over a small mound with volcanic rocks.

I will be back with some more.

Andrew Brown.

 

[MeteorWayne]

Great stuff as usual Andrew. We are getting to know the neighborhoods of our little buddies quite well!

 

[abq_farside]

Truly amazing Andrew. A 90 day mission that has lasted 2000 sols.

In future space history, people we be amazed that the little critters lasted that long.
...

What goes into deciding a mission (like the rovers) length? Is that the time they can "guarantee" the hardware/software will continue to work before it breaking down? I am sure the budget plays into the too.

I wonder if when conceived and designed they thought the rovers may in fact work much longer than the 90 sols originally planned and if they had any outside guess of how long they may actually last.

 

[3488]

Great stuff as usual Andrew. We are getting to know the neighborhoods of our little buddies quite well!

You are very welcome Wayne. I just live for this sort of thing. You may like the LRO update too. Right up your street, but it interests me also. :mrgreen:

Here are four more of my crops from the Calypso Pan.

More layering in Homeplate.

Yet more layering in Homeplate.

Hills in the distance to the right of Von Braun.

Husband Hill with El Dorado sand dunes in the distance.

Truly amazing Andrew. A 90 day mission that has lasted 2000 sols.

In future space history, people we be amazed that the little critters lasted that long.
...

What goes into deciding a mission (like the rovers) length? Is that the time they can "guarantee" the hardware/software will continue to work before it breaking down? I am sure the budget plays into the too.

I wonder if when conceived and designed they thought the rovers may in fact work much longer than the 90 sols originally planned and if they had any outside guess of how long they may actually last.

Hi abq_farside.

Fascinating story about that & well told in Steve Squyres book Roving Mars. Also something that cropped up last year when I met Jim Bell, MER imaging manager in London.

The MERs were GUARANTEED assuming successful EDLs 90 Sols & 600 metres. They were 'slightly' overengineered after the failure of the Mars Polar Lander & NASA had caught a cold with that (also showed with the hugely successful Phoenix Mars Lander).

The engineers actually expected both MERs assuming successful EDLs 150 Sols & perhaps 1.0 KM. Maybe if Mars was really kind to them maybe 200 Sols & approx 2.0 KM.

This immense period of longevity was certainly not anticipated. I still think at least one MER will reach Sol 2,500 at least (assuming dust storms permitting) to be honest. Opportunity certainly, Spirit maybe just with clever engineering decisions from mission control at JPL.

So the answer is, 90 Sols Primary publically expected. Engineers thought 150 Sols maybe 200 sols. Certainly not much more than 200 Sols expected.

Andrew Brown.

 

[abq_farside]

What goes into deciding a mission (like the rovers) length? Is that the time they can "guarantee" the hardware/software will continue to work before it breaking down? I am sure the budget plays into the too.

I wonder if when conceived and designed they thought the rovers may in fact work much longer than the 90 sols originally planned and if they had any outside guess of how long they may actually last.

Hi abq_farside.

Fascinating story about that & well told in Steve Squyres book Roving Mars. Also something that cropped up last year when I met Jim Bell, MER imaging manager in London.

The MERs were GUARANTEED assuming successful EDLs 90 Sols & 600 metres. They were 'slightly' overengineered after the failure of the Mars Polar Lander & NASA had caught a cold with that (also showed with the hugely successful Phoenix Mars Lander).

The engineers actually expected both MERs assuming successful EDLs 150 Sols & perhaps 1.0 KM. Maybe if Mars was really kind to them maybe 200 Sols & approx 2.0 KM.
.....
Andrew Brown.

Thanks for the info Andrew, also for the pics. I may have to pick up Roving Mars.

The color in those images are looking a bit orangish - is that a accurate color? What is causing this coloration - dust storm? Maybe I am just more used to the B&W images that I have forgotten what the "true color" from Mars looks like.