🚀 go-pugleaf

In article <!RJ$MS|@ads.com>, pkenny@ADS.COM (Patrick Kenny) writes:
> In article <72@tucson.sie.arizona.edu> bill@tucson.sie.arizona.edu (Bill Ganoe) writes:
> >         .
> >   Certainly there are tasks that little machines can't handle, but they
> >still might prove very valuable for reconnoitering the area around
> >a landing site.  Each mini-rover could carry one, or a few, sensor(s),
> >and a swarm of "insects" can certainly provide mission robustness that
> >we just couldn't afford with a big "stomper" that tried to be all
> >things to all people.  Conceivably, they could even be used to collect
> >material for sample return missions, although individual samples would
> >be smaller than a stomper might be able to handle. 
> 
> 	What would you consider to be a small machine? 
> 	Something 6 feet long and 3 feet high is not very small.
> 	If it was any smaller I don't think it would be very useful,
> 	it would have a hard time climbing over rocks and sand.
> 	Most of the room would be taken up with drive mechanics and
> 	computer hardware. This is if you consider it to be a stand alone
> 	machine.
> 	 A good idea would be to use robots that act as long range 
> 	sensors for the large robot. They would attach to the underside
> 	of the large robot, it would pick them up and store them.
> 	They would only have to be about 2 feet long and would be in
> 	constant contact, by radio, with the large machine. So they don't
> 	just wander away. If the large robot saw an object with it's
> 	camera, which would be about 12 feet in the air I presume.
> 	It could dispatch a small droid to investigate and relay pictures
> 	or get a sample of the object. This way the large robot could
> 	stay on it's course without running here and there and getting into
> 	possible danger.
> 	 I think every machine has it's place.

Size is not well defined here, and I suspect that it may stay
sort of flexible for a while yet.  I would consider "6 feet long and 3 feet
high" to be "not very small" either.  Brooks has mentioned things like
"3-kilogram Mars rovers", but I don't remember exact linear dimensions
for the rovers that his group at MIT is currently working with.  (It's
definitely less than 6' x 3' though.) 

While something smaller might have trouble climbing over large rocks,
I don't see that it should have much trouble with sand (at least relatively
normal sand).  The approach that Brooks is taking is to have the
mini-rovers back off (or pick themselves up) and try again if they
run into trouble getting over some obstacle. 

There might be a problem with sufficiently large solar cell arrays on
very small rovers, but mini-rovers will certainly have lower power
requirements than their much larger cousins.

Your proposal for mini-rovers to support the mission of a larger "stomper"
seems quite useful, and, perhaps, more realistic in the near term, but
dependence on one (maybe a few) large rovers (and probably one launch
vehicle) makes the overall mission less robust.

But that is still pretty superficial.  I generally agree with you
that every machine has it's place.  The summary to my posting said
"small is beautiful -- maybe", and I noted that the issue wasn't so
much big vs. little, but the perception that NASA has always seemed
to go for the big "stomper" approach to space missions.  

-- 
What?  Me speak for my  | William H. Ganoe      bill@tucson.sie.arizona.edu
employer?               |  Systems & Industrial Engr. Dept, Univ. of Arizona
                        |  Tucson, AZ 85721; USA