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Sunday, June 17, 2012

Low cost development and applications of the new NRO donated telescopes, Page 4.

Copyright 2012 Robert Clark 

 A key reason why these space telescopes developed under a more commercial approach can be done much more cheaply is the more expensive "space qualified" electronics have been found to be unnecessary. This is described by Dr. John Hunter in regards to G-hardening the electronics:

Propellant Delivery to Orbit in Support of Mars Exploration
 with Hydrogen Gas Guns - Dr. John Hunter.

 About 14 minutes in Hunter discusses standard off the shelf components can be used with inexpensive modifications even in regards to gas gun launch at hundreds of g's. As an example he notes cell phones have to be designed to survive such high g's just from being dropped from normal height.

 Radiation resistance can also be done with off the shelf electronics with inexpensive modifications. This is argued by Dennis Wingo whose area of expertise is developing electronics for space use:

Bootstrapping the Moon.
By Dennis Wingo Posted Wednesday, May 7, 2008
Ideas to Lower the Cost of the Effort
Avionics
The first thing to attack is the military industrial complex focus on radiation tolerance for integrated circuits. This one thing has driven the cost of space projects higher and higher as designers have to use several generations old microprocessors, and all types of integrated circuits. This is because there are specifications that individual chips have to meet for latch up and single event upsets. Since most off the shelf (COTS) chips are not particularly radiation hardened, this means that for hardware that goes through the radiation belts or is used in environments where radiation might be a problem that you have to modify existing chip designs to harden them.
This is enormously expensive and the market for these chips is very small in comparison to the commercial market so the number of advanced chips flying is actually very small and the tendency is that the current generation of space qualified chips are several generations behind their commercial brethren with the gap growing year by year. This is why the International Space Station is controlled by 80386 25 Mhz microprocessors that were obsolete in the commercial world in 1992. What it also means is that the tools for software development are ether generations behind as well or are very poorly designed as it is much more expensive for these systems with a very limited market and installed base.
This has been the case since the early 1990's as the amateur radio satellites proved when they basically completely abandoned the concept of space qualified and successfully flew advanced chips. They were able to do this via the concept of shielding the chips with tantalum or other chip and box level shielding techniques. It costs a little weight but with the advances in chip technology, software, and software systems, the total systems costs can be dramatically lowered.
An example of one government organization that understood this was the Strategic Defense Initiative Organization's Clementine mission in 1993 that flew commercial state of the art processors and dynamic RAM memory for the imaging system. It worked fine but the military spec RAD 3000 had a software glitch that opened up a thruster and ended the mission before they could go to an asteroid after successfully operating in lunar orbit for several months. More recent software errors have reportedly crippled much more expensive spacecraft. Today with software growing to as much as 1/3 of the total cost of an advanced spacecraft major savings can be accomplished and schedules compressed by using this approach. So that iPhone that you love may be your communicator on the Moon! The European Space Agency was able last year to get NASA to agree to using the advanced technology of Wi-Fi and the Internet protocol for the lunar outpost. This was a celebrated victory.

http://www.spaceref.com/news/viewnews.html?id=1287

 So off the shelf electronic components can be used with just a little extra weight for shielding.

 This has majorly important results if you already have the space qualified optical components and support structure. It means the space based scopes can then be completed for little more than for the ground versions. 

 This report shows those ground scope costs are surprisingly low compared to the prices now charged for comparable space telescopes:

The Scaling Relationship Between Telescope Cost and Aperture Size for Very Large Telescopes.
Gerard T. van Belle
Michelson Science Center, California Institute of Technology, Pasadena, CA 91125
****@ipac.caltech.edu
and
Aden Baker Meinel & Marjorie Pettit Meinel
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
****@earthlink.net


http://www.eso.org/~gvanbell/publications/van_belle_meinel2_2004.pdf 


 You see the ground scopes in the 2 to 3 meter diameter range are in the $10 to $20 million range and even less. 

This supports the claim of PRI that a commercial approach to the telescope construction can cut costs by one to two orders of magnitude.





  Bob Clark

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