Space Forum / Shuttle / August 2008

On Jul 3, 10:35 am, charliexmur...@yahoo.com wrote:

I wasnt really referring to the obvious things like rubber tires and
oils, i'm more suggesting the framework aspect. I not sure we need a 8
wheeled vehicle that can creep down a crater side. many off road
designs do similiar activies on sand dunes. I'm just suggesting that
we look at what type of off-the-shelf atv-type equipment could be
retrofited. I wonder what type of designs could be done by any of
those customer motorcycle shops you see on discovery channel. That
type of innovative thinking might generate good ideas. And they did
test a lunar cycle during Apollo development so thought was there at
one point.  Many of the off road vehicles, such as dune buggies, are
already minimized for weight by their space frame roll bar
construction. we already developed the wheels and electric motors for
the Lunar rovers before. use them on a existing vehicle. NASA already
spent the money once, why not use it again.

You can't leave out the obvious things though.  They're a huge part of the
design.

Who says we NEED one that has 8 wheels?  But if we do, we want one that will
work in 1/6 G.  Things do change, COG, traction, etc.

Because they spent the money once for a limited lifetime design.  If you
want something that is going to last weeks, you need to design for that.

And keep in mind that you also have to worry about issues like metal
embrittlement, thermal cycling that aren't issues on Earth.

And you need to design for things like, "what if it breaks?"  Even with the
rover on the J missions, their range was limited by possible transit times
if they had to walk back to the LM.

None of these things are simple once you start to look more deeply at it.

On Jul 3, 11:52 am, "dabol...@gmail.com" <dabol...@gmail.com> wrote:

That may be dune buggie 'light" but it isn't aerospace or lunar
light.  Why spend the propellant to send a vehicle designed to support
a 300 lbs person when it only needs to be for a 50 lbs person in lunar
gravity.   Also those motors are over 40 years old, there are better
and lighter one now.  Same goes for the batteries.

"I not sure we need a 8 wheeled vehicle that can creep down a crater
side."

how can you make that call?

I wish it were that simple but it's not.  As everyone else has stated,
given the payload mass restrictions of the launch vehicles and the sheer
cost of getting each pound of payload to the lunar surface, it really
behooves you to build the thing out of lightweight aluminum alloy.  And
as others have stated, the weight carrying capacity and suspension
should be designed for 1/6th G rather than 1G.  Also, the materials and
finishes much be able to withstand the extreme temperature deltas and
high solar flux (especially the high UV flux).

That said, it really shouldn't cost tens of millions to build a lunar
rover.  This stuff really ain't rocket science.  You need to mind the
P&Qs regarding weight and reliability but this vehicle does not operate
at the bleeding edge of technology or extremes of temperature and
pressure like a launch vehicle.  The largest concern would be that if
you drive the rover to a significant distance and it breaks down you
could potentially strand your astronauts farther than their O2 supply
would allow them to walk back.  There are fairly straight forward ways
of mitigating this risk to a reasonable level.

I dare say that if you gave the task to the right private company you
probably should be able to get a design and 1st prototype done for a
million or three and then be able to turn out copies for under $50k
each.  Of course, it is unlikely in the extreme that NASA would ever
select such a company for this development.

Greg D. Moore (Strider) said:

Best laugh I have had reading USENET in days.