beowulf in space

Tomasz Rola rtomek at cis.com.pl
Mon Apr 14 19:29:17 EDT 2003


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On Mon, 14 Apr 2003, Joel Jaeggli wrote:

> On Mon, 14 Apr 2003 chettri at gst.com wrote:
> 
> > Has anybody considered the theoretical aspects of placing beowulfs on a 
> > cluster of satellites? I understand that communication will be slower AND 
> > unreliable,
> 
> Communication to satellites needs to be neither slow nor unreliable, it is 
> generally fairly high latency... It can be quite expensive.
> 
> There are clusters of computers in space. they generally aren't what you 
> would consider heavy computation platforms...

Correct. However, I think that since this question really belongs to s-f
(at least today) one can put some s-f behind the answer...

> The biggest issues with with computer resources in space are:
> 
> mass - 	a large sattellite such as the hughes galaxy 4r bird is around 
[...]

I think mass is an issue when you have to export everything up from the
Earth. It won't be if you start to get materials from celestial sources.
The cost of launch from the Moon should be ca. 6 times less than from the
Earth. Even less when you start to explore asteroids. Kuiper belt should
have plenty of materials. Of course, the cost of building facilities there
is so high that it will take a long time to become feasible and next to
pay off.

> power - solar power and long life cadmium batteries mean your whole 

I think there is plenty of solar power in space. At least within some
specified orbit. It's only that you can't get enough of solar grids there
to use it in a practical way. BTW, some people are reconsidering the use
of atomic power up there.

http://www.spacedaily.com/news/oped-03i.html

(There are some links at the bottom of the page too).

> radiation hardening - without 50 miles of atmosphere overhead we're kinda 

Yes it is an issue. Perhaps it could help if you buried a cluster under
the surface of the Moon or put it on the dark side of Mercury (you would
need to move slowly your cluster there to avoid being rotated into the
very hot sunlight - not very practical, I think).

It seems that magnetic field helps but this page:

http://isaac.exploratorium.edu/~pauld/activities/magnetism/magnetismofplanets.html

shows that Earth-like field is scarce in Solar System. Placing such
systems, especially built from off the shelf components, on orbit is
probably not very bright idea unless you can protect them.

> thermal management - air cooling doesn't work given no atomosphere... even 

I'm not a specialist but I think you can force the (air | water) flow in
space. Otherwise, astronauts would have very dangerous time sleeping in
one place for few hours, with no ventilation at all (CO2 bubble growing
around their heads).

> expected service life - if you plan on go to the expense of putting it in 

Today, the longer you can use orbital device the better but nobody applies
this kind of measures to clusters. So you are right it would not be worth
to expedition units from Earth. On the other hand, the use of automated
production facilities, maybe on the Moon, would make the project possible.
When connected with some inexpensive transport system (who knows,
electromagnetic cargo ejectors or orbital lift) it could provide upgrades
and replacements (provided that you solve the radiation problem).

It is also quite possible that some time from now the Moore's law will no
longer hold. If so, the computing unit longevity would be measured in tens
of years. So even without cheap transportation it may be ok to hold it on
orbit for 20 years and still have fun (but not if you use today's cpus).

technology vs automation issues - 

- From what I know the technology for all this is right now very primitive
and/or requires human attention to work properly. Maybe you should ask the
question again about 10-20 years from now. Frankly, I don't see much sense
in putting cluster on orbit and than paying lots of money for sending
human operators there too. So automatic operation is probably a must for
this kind of projects.

mental sanity and business issues - (sorry, I just couldn't stop myself
:-) )

BTW I can't understand WHY anybody would like to place a cluster on orbit?
For the control of some weapon system with sofisticated AI? For autonomic 
management of exploration mission? Do you have any concept of
computational device that would work better on the orbit, by chance?

Environmental issues? Nah. I doubt if we could build such big clusters
anytime soon. Milions of units in one place? What for...

You know, the idea is nice but if what I know is correct, one can do the
same job on the surface, under the surface and even under the sea for a
fraction of cost and without waiting for better tech.

> > and it would restrict the set of problems that could be solved. I'm looking 
> > for papers/tech reps etc on the subject.
> > 
> > Regards,
> > 
> > Samir Chettro

Probably you would suffer from signal propagation times. The longest path
you have to deal on the Earth's surface is some 20 000 km. In case of a
geostationary cluster the diameter is about 70 000 km and even longer if
you want to send via the neighbours. Ok, I expect that you want to have
more than one cluster up there. So I think you are restricted to the tasks
with high processing / communication ratio.

[...]
> -- 
> -------------------------------------------------------------------------- 
> Joel Jaeggli	      Academic User Services   joelja at darkwing.uoregon.edu    
> --    PGP Key Fingerprint: 1DE9 8FCA 51FB 4195 B42A 9C32 A30D 121E      --

bye
T.

- --
** A C programmer asked whether computer had Buddha's nature.      **
** As the answer, master did "rm -rif" on the programmer's home    **
** directory. And then the C programmer became enlightened...      **
**                                                                 **
** Tomasz Rola          mailto:tomasz_rola at bigfoot.com             **

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