Re: [amsat-bb] RE: PCSAT Cost and Satellites

[Jim White <jim@xxxxxxxxxxxxxxxxxxxxx>]

Bob,

Nice list, but you left out an item or two.  In no particular order:

- Design or buy a separation system that your ride is comfortable with, 
then prove it works with testing
- Design your transmitter system so it can't come on while you are on the 
rocket, then prove it can't possibly come on under any condition (but 
assure yourself it will come on when you tell it to, but not before a few 
hours in space to assure no corona problems).  If the Shuttle, make and 
prove three ways that prevent the TX from coming on (and none can be "it 
needs a command from the ground").
- Keep everything extraordinarily clean so you don't contaminate the rocket 
or other payloads.
- Assure you don't use anything anywhere that will outgas in vacuum, then 
prove it with a thermal vacuum test.
- Assure you don't use anything that will contaminate the TV test chamber, 
like cadmium plated connectors
- Track the origin of all materials used so you can prove the last two
- Design your power system so you can recover from a totally dead battery
- Design your power system so it doesn't - through some error or bad 
situation - pull the battery all the way down and kill it, or overcharge it 
and kill it
- Prove parts won't fall off when you vibrate it to the levels expected for 
launch, +6 dB
- Prove parts won't come loose inside under those conditions
- Assure the parts are arranged so the center of gravity is where the 
launcher want's it, then prove it with a CG/MOI test
- Design it stiff enough so it's natural vibration frequency is > 100 hz so 
it won't amplify the acoustic or mechanical vib from the launcher, yet no 
so stiff as to 'ring'
- Tell the launcher exactly what you mass will be two to three years in 
advance then hit it right on.
- Assure you fit in the envelope specified, including antennas
- If you have a deployable, expect to be able to prove it won't deploy when 
it shouldn't under any combination of up to three failures
- If you have pyros, expect to use only 'approved' devices, expect 
extraordinary safety measures, expect to prove they can't possibly fire 
when they shouldn't under any combination of up to a zillion failures
- If either of the above add 1 year to the prep time and paper work 10 
times the weight of the devices
- If your are going to charge batteries on the vehicle while awaiting 
launch expect paper work in excess of the weight of the power supply
- Make darn sure you have a ground station that can in fact talk to your 
satellite after launch
- Meet the magnetic cleanliness spec of the launcher and other payloads
- Prepare and test, then have approved, a set of written procedures for 
every single evolution and contingency you need to do at the integration 
and/or launch site.  Then darn well don't deviate from them.
- Expect 3 to 7 people looking over your shoulder constantly when doing 
those procedures to assure you are safe and aren't deviating
- Provide all your vib, CG, MOI data to the launcher folks so they can do a 
coupled loads analysis and assure the combined affect of all the payloads 
meets the launcher spec
- Design the power system so shorts in it won't cause the batteries to 
explode or outgas bad stuff -or cause the wires to burn up and contaminate 
other stuff or start a fire, then prove it with testing,
- Provide your bird, or an accurate model, for a fit check with the 
launcher a year or three in advance, then don't deviate from that
- If on the shuttle assure all external fasteners are staked so nothing can 
possibly come off and foul the separation mechanism.
- Also assure there are no sharp things sticking out that could puncture a 
space suit.
- Design a way to absorb anything that does leak from your batteries so it 
doesn't contaminate other payloads, the rocket, the sep mechanism
- When you go to the launch site be prepared to wait around (or leave your 
bird and come back) for weeks or months
- Build a mass dummy so if your precious satellite craps out at the last 
minute you can hand the launcher something that has the same mass, CG/MOI 
for them to launch.  Grit your teeth, pay the money, but keep your 
satellite to fix and fly a few years later.

Jim



- At 01:08 PM 03/29/2004 -0500, Robert Bruninga wrote:
>Someone asked:
> >
> >What resources did you use to learn how to build a satellite???
> >I'm sure there is more involved than just putting together some
>parts.
>
>Well, the easy answer is get a degree in Aerospace, EE and Systems
>engineering.  But assuming that you are talking about a bunch of
>HAMS that already know how to build radios and modulators
>and demodulators, then all they need to do is this:
>1) Make it gosh-awful reliable
>2) Make it work in a Vacuum
>3) Make it work under tremendous vibration
>4) Make it work HOT (60C) and cold (-40C)
>5) Thermal design is absolutely cricical.  The wrong
>     color paint can change your temperature 100 degrees
>6) Every possible bad state it can get in, IT WILL.
>7) Make it ALWAYS recoverable from  ANY state
>8) Design a power system based on the orbit and sun angles.
>9) FInd someone to launch it for you and who will
>     feel commfortable putting your bucket of bolts on
>     their $100,000,000 launcher
>10) IE, it must be SAFE, SAFE, SAFE, SAFE
>11) It must not outgass or do anything that would
>       harm other payloads and not have ANY parts
>       that will separate even for the next 100 years..
>etc...
>12) Have several bureaucrats working for you that
>have years of free time to handle and produce all
>the paperwork needed.
>
>Thats about all there is to it..
>Bob
>
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