'In orbit' inspection craft..

"Andrew Thompson" wrote:

After reading some of the recent discussions re the shuttle
loss I began to wonder at the practicality of small
'inspection craft' permanently in orbit to rendesvous with
shuttles and and other high risk / high value craft to gain
a closer inspection for damage.

If the orbits were known far enough in advance, perhaps
low thrust ion engines may be sufficient to maneuver the
craft into position for each successive encounter?

But, would ion engines be practical for maneuvering
close to the shuttle (the inspection craft would
obviously need to 'traverse' the shuttle)?

Is this completely impractical? Thoughts?

Practical, I can't say. But it makes a lot of sense to me to have some
sort of simple waldo-type robotic platform up there. It doesn't have to be
fancy, fast or smart. But something with eyes, mobility, and a basic set
of tools could probably be really useful.

Such a device could sit idle until needed, just like any other tool. It
could manoeuver on solar-powered ion thrusters most of the time, thus
requiring little fuel. I envision something with little or no on-board
intelligence, being almost entirely ground-controlled. It could visit
virtually any orbiting object object given sufficient time, performing
visual inspections, freeing stuck panels, and other such things that seem
to come up occasionally.

Certainly, anything complex would be impractical for such a platform. But
there are a lot of simple jobs that can't be done now, that might keep
expensive space hardware off the junk list.

/kenw
Ken Wallewein CDP,CNE,MCSE,CCA,CCNA
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net

"Andrew Thompson" wrote in message ...

But, would ion engines be practical for maneuvering
close to the shuttle (the inspection craft would
obviously need to 'traverse' the shuttle)?

Rather than have it in a separate orbit, why not carry it?

http://www.astronautix.com/craft/aercam.htm
http://spaceflight.nasa.gov/station/assembly/sprint/
http://aercam.nasa.gov/

Maybe 50kg if you go wild on a cargo bay dock for the full-
sized AERCam.

Mike Miller, Materials Engineer

I wonder if it'll be possible for such a micro-sat to enter an orbit around
the orbiter? Will the air drag (and solar wind drag) be larger than the
attraction of the microsat to the shuttle? Assuming 100t shuttle and microsat
at 100m from it, the gravitationsl acceleration is about 6.6E-10 m/Sec^2
(unless I miscalculated something).

So v^2/r = 6.6e-10, r=100, and v = .26 mm/s, orbital period about a month.
Stick with the cold gas thrusters.

(Arie Kazachin) wrote in message ...

It really strange how NASA so far haven't invested in such a safety
equipment as remotely operated "eyes" - it should weight only a fraction
of MMU.

You mean equipment like the AERCam NASA developed 6 years ago?

Mike Miller, Materials Engineer

JRS: In article , seen in
news:sci.space.tech, Arie Kazachin
6.net posted at Thu, 10 Jul 2003 23:46:35 :-

I wonder if it'll be possible for such a micro-sat to enter an orbit around
the orbiter? Will the air drag (and solar wind drag) be larger than the
attraction of the microsat to the shuttle? Assuming 100t shuttle and microsat
at 100m from it, the gravitationsl acceleration is about 6.6E-10 m/Sec^2
(unless I miscalculated something).


Since the Orbiter is always well within the Roche Limit, which would be
at an altitude of 1.45 Earth radii if the Orbiter had the same density
as the Earth, which it does not, we know that tide alone will prevent
orbiting.

URL:http://www.merlyn.demon.co.uk/gravity3.htm

Ignoring that : Moreover, the period of an orbit is two hours if the
average density spherically within it is that of the Moon, being about 4
gm/cc. The density in question, 100t in 100m radius, is 100E6 / 1.33 pi
(1E4)^3 which is about 2E-5 gm/cc, less by a factor of about 200000; so
the period would be of the order of 900 hours (proportional to inverse
square root of density; gravity2.htm). The Orbiter stays up for of the
order of 350 hours.

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

Henry Spencer wrote:
snip "should you take it with you"
Almost certainly, if such inspection is desirable, it is better for each
such craft to carry its own little expendable inspector. Electronics
miniaturize well, battery life need be only a few hours, and if the only
maneuvering needed is local, a small cold-gas thruster set need not weigh
very much.

You might even get away with only an attitude stabilised camera with a
zoom lens that you can manoever round.
Throw it out the cargo bay, move off a hundred meters, and do a slow roll.
This would probably not be suitable for a routine inspection tool.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
"The device every conquerer, yes, every altruistic liberator should be required
to wear on his shield... is a little girl and her kitten, at ground zero"
- Sir Dominic Flandry in Poul Andersons 'A Knight of Ghosts and Shadows'