Re: [amsat-bb] Re: Useless CubeSats

["Robert Bruninga" <bruninga@xxxxxxxx>]

Well, as a mentor for two cubesats, the idea (below) that 
CUBESAT designs are not real satellllites and do not
have to address all of the pillars of Aerospace design,
is just plain missinformed.

Not only does everyone of these aspects of spacecraft
design have to be addressed, it also has to pass the
FULL NASA Design reviews and every aspect of the design
is held to the SAME exact specifications and standards
as any other spacecraft.   THe only difference is that
we used to say that the paperwork for a satellite design
weighted 10 times  the mass of the satellite.  SInce all
the PAPER work is the same even for a cubesat, but it
is 10 times smaller, now the ratio of paper and detail
design and specifications and testing is approaching
100 to one!

Any thought that a cubest is just a toy in space is simply an
uninformed opinion.   de Wb4APR, Bob

SOlar, Thermal, Mechanical, ELectrical, Processors,
telemetry, structural, materialsall aspects of spacecraft design are
not involved in
CUBSsat design is just wrong.

t is clear this person
has never bu

>>> "William Leijenaar" <pe1rah@hotmail.com> 2/8/05 1:59:28 AM >>>
Hi AMSATs,

I like to give some comment on your reply:

>Now, come on...the big sat and the little sat have all the same things
- 
>solar
>cells, batteries, control circuits, comm circuits, mission specific 
>circuits,
>attitude parts...and they work the same. Bill, the ICs are just the
same, 
>the
>solar cells too. Same Teflon wire, Kapton tape, potting compound,
machined
>aluminum...just less of it. And less is cheaper, easier to manage,
test and
>design for some who have never done so.

Maybe I didn't explain to well why a CUBESAT can not be compaired with
a 
real satellite.
Yes, they are both made of the same materials, but that doesn't mean
they 
have the same problems. A cubesat has no high powers, not that much
high 
temperature problems, no difficult propulsion systems. They have mostly

simple tranceivers, only omni-antenna's etc etc...

With a bigger satellite you have real physical problems to solve, that
can 
not only be fixed with a program. There you even have to think where to

place components to get ride of the heat (e.g PA) or find ways to
shield 
sensitive parts (like uProcessors), think out how to place antennas in
a way 
they "light" the earth without interfering other radios on board.
Then you need to deal with high current/voltages that must be converted
in 
other voltage levels, in an efficient way (not with simple
regulators).
When the satellite is spin-stabalized, all the payloads have to be
weight 
balanced.
>
> > Its like giving a truck-mechanic-student a small truck model to
learn 
>how to
> > repair a truck engine.

>A good analogy - but to make it complete - the truck model runs, just
like 
>a big
>truck. It doesn't haul as much, but it runs.

When you think that an electrical motor work equal to a diesel
motor...
They are both made of metal, but never work the same...