NASA should send many SMALL Mars rovers to survey

It seems it would be more logical to make a broad survey of Mars
*first* before sending single billion-dollar mega-lab-rovers. That way
you explore the best candidates later with expensive rovers rather than
hope for a lucky spot.

I am thinking NASA could send a dozen small rovers about the size of
Sojourner (without Pathfinder) to simply look around at a wide variety
of spots, including difficult terrain. Such rovers would have mostly or
only remote sensing tools like the mini-TES, multi-spectral imaging,
soil magnifier, and maybe a scaled-down Mossbauer Spectrometer.

If these survey rovers are kept simple and cheap, then they could be
sent to high-risk areas like Valles Marineris. Planners are currently
too timid to try such areas because of the risks. But big risk tends to
mean bigger science. The orbiting mini-rover holder would simply have a
spare if one mini-rover flubs up in a given landing area.

For example, maybe 12 spots are ranked in priority. If #7 meets
disaster, then #8 goes in its place and spot #12 is simply skipped.
Just assume up front that 2 or 3 will be lost so that planners have the
freedom to target high-risk areas.

Something like this is going to have to be done anyhow before landing
humans.

A variation of this approach is even smaller rovers with only cameras
and TES such that 30 or so can be sent all over. The drawback to this
size is that they may not be able to reach nearby mountains or craters
due to their size. Perhaps more pin-point landing technology can
compensate for this lack of mobility.

-T-

"topmind" wrote in message
ups.com...
It seems it would be more logical to make a broad survey of Mars
*first* before sending single billion-dollar mega-lab-rovers. That way
you explore the best candidates later with expensive rovers rather than
hope for a lucky spot.

My concept is to have a big rover travel at 5 mph and 20 little rovers
travel at 20 mph. Little rovers would bring stuff back to the big rover.
The big rover would have a satellite dish capable of communicating with
Earth. If the big rover traveled in a straight line and the little rovers
traveled up to 10 miles away from the big rover, then you would end up with
a 20 mile wide swath of land being surveyed. You might want two big rovers
so you don't have a single failure point for the mission.

It is possible to circle Mars 3 times a year at 5 mph. If the big rover
took time out for drilling and rest, you'd get a single circuit in a year.
A 2 year mission could circle the equator and then circle over the poles.
That would give you a good general idea of what Mars is like.

The cost-benefit math doesn't work. Try it.


"topmind" wrote in message
ups.com...
It seems it would be more logical to make a broad survey of Mars
*first* before sending single billion-dollar mega-lab-rovers. That way
you explore the best candidates later with expensive rovers rather than
hope for a lucky spot.

I am thinking NASA could send a dozen small rovers about the size of
Sojourner (without Pathfinder) to simply look around at a wide variety
of spots, including difficult terrain. Such rovers would have mostly or
only remote sensing tools like the mini-TES, multi-spectral imaging,
soil magnifier, and maybe a scaled-down Mossbauer Spectrometer.

If these survey rovers are kept simple and cheap, then they could be
sent to high-risk areas like Valles Marineris. Planners are currently
too timid to try such areas because of the risks. But big risk tends to
mean bigger science. The orbiting mini-rover holder would simply have a
spare if one mini-rover flubs up in a given landing area.

For example, maybe 12 spots are ranked in priority. If #7 meets
disaster, then #8 goes in its place and spot #12 is simply skipped.
Just assume up front that 2 or 3 will be lost so that planners have the
freedom to target high-risk areas.

Something like this is going to have to be done anyhow before landing
humans.

A variation of this approach is even smaller rovers with only cameras
and TES such that 30 or so can be sent all over. The drawback to this
size is that they may not be able to reach nearby mountains or craters
due to their size. Perhaps more pin-point landing technology can
compensate for this lack of mobility.

-T-

Michael Rhino wrote:
My concept is to have a big rover travel at 5 mph and 20 little rovers
travel at 20 mph. Little rovers would bring stuff back to the big rover.
...
It is possible to circle Mars 3 times a year at 5 mph. If the big rover
took time out for drilling and rest, you'd get a single circuit in a year.

That would of course be nice, but quite unrealistic plan. A rover, which
would be able to travel 20 mph, is quite similar to the DARPA Grand
Challenge cars:
http://www.darpa.mil/grandchallenge/
Except that this would happen on Mars, and there are now combustion motors,
no GPS, no real-time telemetry etc. It would be possible to make a rover
that could travel 20 mph in Mars, but could it then avoid obstacles, plan
its route, and maintain that speed for longer time than few tens of seconds
(taking into account the energy question also)?

The drilling is also very energy-consuming, and it "anchors" the rover in
its place for the duration of the operation. Which could take hours or even
sols. See drilling energy/time estimates:
http://masa.net/space/phd_thesis/ - Doctoral Thesis (pdf), Chapter 7.7.
The sample analysis has to be performed also mostly while in still/rest.

To get wide-range measurements of Martian surface conditions, I would
propose a network of static landers, such as - for example - the MetNet:
https://netlander.fmi.fi/MET-NET/
http://www.ava.fmi.fi/metnet/landing_concept.php

Regarding the rover issue, I think that it would be too expensive to send
a swarm of small rovers. Although the MSL (NASA 2011) and ExoMars (ESA 2011)
rovers are big and expensive, and "carrying all eggs in one basket", I
believe that they are more cost-results-effective than a bunch of small
rovers without such a soffisticate capabilities that the big ones have.

Matti Anttila
Finland

Michael Rhino ) wrote:
: "topmind" wrote in message
: ups.com...
: It seems it would be more logical to make a broad survey of Mars
: *first* before sending single billion-dollar mega-lab-rovers. That way
: you explore the best candidates later with expensive rovers rather than
: hope for a lucky spot.

: My concept is to have a big rover travel at 5 mph and 20 little rovers
: travel at 20 mph. Little rovers would bring stuff back to the big rover.
: The big rover would have a satellite dish capable of communicating with
: Earth. If the big rover traveled in a straight line and the little rovers
: traveled up to 10 miles away from the big rover, then you would end up with
: a 20 mile wide swath of land being surveyed. You might want two big rovers
: so you don't have a single failure point for the mission.

: It is possible to circle Mars 3 times a year at 5 mph. If the big rover
: took time out for drilling and rest, you'd get a single circuit in a year.
: A 2 year mission could circle the equator and then circle over the poles.
: That would give you a good general idea of what Mars is like.

The problem is that Mars, though without oceans, isn't like a cue ball.
Olympus Mons and Valles Marineris are cases in point.

Check out: http://ltpwww.gsfc.nasa.gov/tharsis/...phy_from_MOLA/
and: http://starryskies.com/solar_system/...s_surface.html

Eric

Matti Anttila ) wrote:
: Michael Rhino wrote:
: My concept is to have a big rover travel at 5 mph and 20 little rovers
: travel at 20 mph. Little rovers would bring stuff back to the big rover.
: ...
: It is possible to circle Mars 3 times a year at 5 mph. If the big rover
: took time out for drilling and rest, you'd get a single circuit in a year.

: That would of course be nice, but quite unrealistic plan. A rover, which
: would be able to travel 20 mph, is quite similar to the DARPA Grand
: Challenge cars:
: http://www.darpa.mil/grandchallenge/
: Except that this would happen on Mars, and there are now combustion motors,
: no GPS, no real-time telemetry etc. It would be possible to make a rover
: that could travel 20 mph in Mars, but could it then avoid obstacles, plan
: its route, and maintain that speed for longer time than few tens of seconds
: (taking into account the energy question also)?

: The drilling is also very energy-consuming, and it "anchors" the rover in
: its place for the duration of the operation. Which could take hours or even
: sols. See drilling energy/time estimates:
: http://masa.net/space/phd_thesis/ - Doctoral Thesis (pdf), Chapter 7.7.
: The sample analysis has to be performed also mostly while in still/rest.

: To get wide-range measurements of Martian surface conditions, I would
: propose a network of static landers, such as - for example - the MetNet:
: https://netlander.fmi.fi/MET-NET/
: http://www.ava.fmi.fi/metnet/landing_concept.php

: Regarding the rover issue, I think that it would be too expensive to send
: a swarm of small rovers. Although the MSL (NASA 2011) and ExoMars (ESA 2011)
: rovers are big and expensive, and "carrying all eggs in one basket", I
: believe that they are more cost-results-effective than a bunch of small
: rovers without such a soffisticate capabilities that the big ones have.

I dunno, I think balloons would be the best way to explore Mars,
especially if you plan on using several of them.

See: http://www.spacedaily.com/news/mars-balloon-04a.html

Eric

: Matti Anttila
: Finland

In article . com,
topmind wrote:
I am thinking NASA could send a dozen small rovers about the size of
Sojourner (without Pathfinder) to simply look around at a wide variety
of spots, including difficult terrain...

Bear in mind that Sojourner relied on Pathfinder for communications, and
had a relatively short working life because of a lightweight short-lived
battery.

Such rovers would have mostly or
only remote sensing tools like the mini-TES, multi-spectral imaging,
soil magnifier, and maybe a scaled-down Mossbauer Spectrometer.

Um, you realize that you're asking for something fairly close to an MER
there? Deleting the grinding/brushing tool and the APXS, and trimming
down the size of the Moessbauer spectrometer, won't save a whole lot.
This definitely isn't a Sojourner-sized rover, and it definitely isn't
simple and cheap.

I'm inclined to agree that dropping a bunch of modest-sized rovers would
be a good idea. But it won't be a cheap project. If you want respectable
remote-sensing capabilities, they can probably be smaller than the MERs,
but not dramatically so -- you'll still get only one per Delta II launch.
Scale back the objectives some and you can probably get two on a Delta II,
or several on an Atlas V. The desire to go into rough terrain means,
alas, that you have to keep the airbag landing system, which is complex
and heavy.

...The orbiting mini-rover holder would simply have a
spare if one mini-rover flubs up in a given landing area.

What did you plan to launch this on? A Saturn V? The only reason that
Mars Pathfinder or a single MER could fit on a Delta II at all was that it
*didn't* stop off in Mars orbit before landing. Going straight to the
surface means that the braking can all be done aerodynamically, while
entering orbit requires that quite a bit of it be done with rocket fuel.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Henry Spencer wrote:


Bear in mind that Sojourner relied on Pathfinder for communications, and
had a relatively short working life because of a lightweight short-lived
battery.


The short lived battery was on Pathfinder, not on the Sojourner rover.
If I recall correctly, Pathfinder had both a rechargeable and a
non-rechargeable battery. It was when the non-rechargeable battery died
when the extended mission ended, because the rechargeable battery alone
was not enough to power the communications gear. The non-rechargeable
battery was designed to last for a month and actually lasted almost
three months.

Anyone can confirm this?

In article . com,
Alejandro Zuzek wrote:
Bear in mind that Sojourner relied on Pathfinder for communications, and
had a relatively short working life because of a lightweight short-lived
battery.

The short lived battery was on Pathfinder, not on the Sojourner rover.

Both.

Sojourner had a non-rechargeable battery, meant primarily to permit doing
APXS measurement runs at night (when instrument noise was much lower due
to it being colder), but also useful to keep the computer up and permit a
quick start in the mornings. It died at the beginning of September, about
two months after landing. A non-rechargeable battery was deemed perfectly
adequate, given that the length of the rover's primary mission was one
week! As it was, it died a little earlier than expected; possibly the
APXS was using more power than expected, there being little data on that
because most of the other rover electronics were shut down at night to
conserve battery power. Losing the battery messed up the APXS data and
generally hampered rover operations, but didn't quite kill it.

Mars Pathfinder had a rechargeable, but short-lived, silver-zinc battery
system. Again, with a short mission -- primary mission one month -- long
battery life was not a requirement, and a silver-zinc battery was lighter
than a longer-lived type. The battery died at the end of September, and
that shut things down for good, because while Sojourner had isotope
heaters, MP relied on battery power to keep its electronics warm at night.
Without the battery, the huge temperature swings quickly killed the
electronics. (The transmitter was heard faintly a couple of times in the
ensuing week or so, but full contact was never restored. In early
November JPL gave up.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

Ten Quidado wrote:
The cost-benefit math doesn't work. Try it.

Let's say the budget is 2 billion dollars.

Expensive rovers with biology labs: 2 (a billion each)

Spirit-type rovers: 8 (250 million each using existing design)

Mini-rovers: 25 (80 million each)

If you make them have only remote-sensing (and a mangifier), the price
might even go down more. The idea is to do a *wide* survey first so
that more expensive follow-on bots pick the better areas instead of
rely on luck.

And, much of the driving work can be farmed out to universities with
interns because the risk acceptance per rover is relaxed.



"topmind" wrote in message
ups.com...
It seems it would be more logical to make a broad survey of Mars
*first* before sending single billion-dollar mega-lab-rovers. That way
you explore the best candidates later with expensive rovers rather than
hope for a lucky spot.

I am thinking NASA could send a dozen small rovers about the size of
Sojourner (without Pathfinder) to simply look around at a wide variety
of spots, including difficult terrain. Such rovers would have mostly or
only remote sensing tools like the mini-TES, multi-spectral imaging,
soil magnifier, and maybe a scaled-down Mossbauer Spectrometer.

If these survey rovers are kept simple and cheap, then they could be
sent to high-risk areas like Valles Marineris. Planners are currently
too timid to try such areas because of the risks. But big risk tends to
mean bigger science. The orbiting mini-rover holder would simply have a
spare if one mini-rover flubs up in a given landing area.

For example, maybe 12 spots are ranked in priority. If #7 meets
disaster, then #8 goes in its place and spot #12 is simply skipped.
Just assume up front that 2 or 3 will be lost so that planners have the
freedom to target high-risk areas.

Something like this is going to have to be done anyhow before landing
humans.

A variation of this approach is even smaller rovers with only cameras
and TES such that 30 or so can be sent all over. The drawback to this
size is that they may not be able to reach nearby mountains or craters
due to their size. Perhaps more pin-point landing technology can
compensate for this lack of mobility.

-T-