There seems to have been increasing interest in the last decade or more in microsatellites (small satellites with masses in the 10 to 100 kg range), nanosatellites (1 to 10 kg range) and even smaller satellites. Low costs, the ready availability of commercially available systems and expanding capabilities resulting from ever improving technology make these classes of satellites attractive for groups, like students, trying to minimize cost to perform meaningful work in space. But nanosats and especially microsats are nothing new nor is the desire for students to get involved in such projects. Miniaturized satellites have existed since the dawn of the Space Age over half a century ago and there is much that can be learned from these earlier projects.
I was reminded of that fact this past year. Having been through two moves in the space of less than two years, I have been forced to sort through box after box of old things in order to consolidate and minimize my storage needs. Among those things were boxes of old textbooks, notebooks, assorted memorabilia and just plain junk from my college years so long ago. A lot of it was just tossed into the recycle bin while a few of the more cherished (and thinner) items ended up being placed into new photo albums/scrapbooks that I started putting together between the first and second moves to replace my old albums that were literally disintegrating from age.
Among the many long-forgotten items I found was a pamphlet from the Independent Space Research Group (ISRG) in Troy, NY about their big project, the Amateur Space Telescope (AST). I first became aware of the AST from an article in Astronomy published in October 1980 right at the very beginning of my freshman year at the University of Lowell (now the University of Massachusetts – Lowell). The AST project did not get my attention again until just as I was about to begin my junior year when Sky & Telescope published an excellent, detailed article about the AST and its progress in their August 1982 issue. By this point I was the vice president (and within a few months, president) of the local chapter of the Society of Physics Students and was considering various projects for my fellow physics students and me to get involved in. And the fact that it had been a dream of mine since childhood to launch my own satellite only served to increase my interest in AST further still (see “The Space Shuttle and the dreams of a ten year old”). So, this being the days before the internet, I sent a request by mail to ISRG for more information and they sent me a pamphlet – the one I discovered in a box of old college things over thirty years later.
The Amateur Space Telescope project got its start in early 1979 when a handful of enthusiastic students at Rensselaer Polytechnic Institute (RPI) in Troy, NY realized that they could build their own space telescope using off-the-shelf hardware and launch it as a payload on the soon-to-be-introduced Space Shuttle. The AST would be the amateur (and much less expensive) equivalent of NASA’s Hubble Space telescope (HST) then under development. At this time NASA was advertising various applications for their new Space Shuttle and, among other things, they were encouraging universities and student groups to get involved as part of their educational and public outreach efforts. Among those programs was the Get Away Specials (GAS) which used small standardized canisters that could hold experiments or even small satellites for deployment while the Space Shuttle was in orbit. AST would be designed specifically to take advantage of NASA’s GAS program if not for deployment (an option that fell into disfavor as the project matured) but for in-flight testing of critical satellite systems.
AST was to be a 80-kilogram satellite (towards the upper end of today’s microsat mass range) built around a 45-cm Ritchey-Chrétien telescope. The telescope would be mated with an equipment bay shaped like an octagonal prism 50 cm across and 50 cm long giving the AST a total length of 185 cm. A deployable solar array 1.5 meters across would provide 60 watts of power. The attitude control system consisted of a set of star sensors and four flywheels – three primaries and a spare. The entire system was controlled by an RCA 1802 microprocessor whose silicon-on-sapphire design made it resistant to radiation and static charge. The RCA 1802 was widely used on satellites of the day and several were used in various systems in NASA’s Galileo spacecraft to Jupiter.
Ideally the satellite, which would have a nominal lifetime of two years, would be launched into a 500-km Sun-synchronous orbit so that its solar panels would always be in sunlight. But since AST would need to take advantage of any opportunity to get into orbit on the Space Shuttle or as a piggyback payload on a commercial launcher, there was considerable flexibility on this matter.
AST would have carried a set of instruments that were very impressive for the day. The main instrument was a pair of 256 X 256 pixel CID imaging arrays supplied by General Electric that would use a set of filters to acquire narrow- or wide-angle images which would cover the spectrum from 190 nm in the ultraviolet (UV) to about 1.0 μm in the near infrared (NIR). The resolution of the images would be comparable to the diffraction limit of the optics ranging from 0.35 arc seconds in the NIR to 0.02 in the UV. This performance far exceeded what amateurs (or even most professionals!) were capable of doing in this age where imaging with specially prepared photographic film was still the norm. With integration times as long as ten hours, objects down to the 23rd magnitude could be detected. Based on the accounts of the time, it seems that the AST participants were quite interested in using these high resolution imaging capabilities for monitoring the planets especially weather on Mars and Jupiter where features as small as 70 km and 700 km, respectively, could be imaged. It was envisioned that AST could perform regular planetary patrols alerting the HST to take a closer look at anything interesting.
In addition to the CID imaging arrays, AST would also carry a trio of photometers to measure star brightnesses at various wavelengths from the UV possibly as far as into the IR. Rounding out the AST’s complement of instruments was a UV spectrograph. Images as well as other data would be transmitted to the ground via a pair of 0.5-watt transmitters so that amateurs with about $400 worth of equipment could receive the broadcasts and reproduce the pictures. Amateur ham radio operators in organizations like AMSAT had been relaying messages via amateur-built satellites like the OSCAR (Orbiting Satellite Carrying Amateur Radio) series since 1961 so the technology as well as the knowledge and infrastructure for communicating with and controlling an amateur satellite in orbit were already available.
AST had a total estimated cost of just $100,000 (or about $285,000 in today’s money). Costs were kept low by using off-the-self equipment where possible, from donations of time and expertise from university students, faculty and other volunteers as well as donations of equipment from various companies. Expenses were covered from memberships and corporate donations to ISRG. As little as $15 per year was enough to make one a “supporting member” where you would get a bi-monthly newsletter, a vote in ISRG affairs and the chance to participate in ISRG projects.
Now almost a third of a century later, I can not help but wonder about the fate of AST. Neither myself nor my classmates decided to get involved with the project. Our various research interests at the time took us in different directions. By early 1984, construction of AST was well underway and it was hoped that it could be launched in 1985. Unfortunately there was no procedure or hardware in place (aside from GAS) to launch what would today be classified as a “microsat” from the Space Shuttle. But while negotiations with NASA and other potential launch providers continued, ISRG intended to use a GAS canister donated by the Inter-Space Society to provide a test flight for many of AST’s electronic and mechanical components. In early 1984 they anticipated that they would fly on Shuttle mission number 14.
After this, my information on AST and ISRG quickly fades away. No GAS payloads flew on the 14th Shuttle mission, STS-51L, and my review of various Shuttle mission payload manifests before and after this flight has yet to find an AST-related GAS flight taking place between early 1983 and the beginning of 1986. The Space Shuttle Challenger accident in January 1986 and the subsequent 32-month stand down of the Shuttle program would have severely affected the prospects of getting AST launched not to mention quash hopes of using GAS for an early test flight. Changes in NASA’s launch and safety policies involving the Space Shuttle would have complicated matters even further.
The last I heard of ISRG was in early 1987 when their president at the time, Jesse Eichenlaub, became involved with leaders from other amateur astronomical groups in the formation of the Hubble Space Telescope Amateur Astronomers Working Group. An insert in the September 1987 issue of Sky & Telescope titled “Popular Astronomy Handbook” included ISRG in its list of astronomy clubs and societies but that is the last mention I can find of them.
I know that AST was never launched but ISRG did seem to pioneer the technology and techniques that are used by student groups today in small nanosat projects taking place around the world. I assume that the AST and ISRG faded away when the promised prospects of easy access into space using the Space Shuttle quickly evaporated in the wake of the Challenger disaster. But all these years later, I am still left wonder exactly what happened to the Amateur Space Telescope?
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“Amateur Space Telescope”, Astronomy, Vol. 8, No. 10, pp. 59-60, October 1980
The Amateur Space Telescope Project, ISRG pamphlet, Undated (c1982) [PDF]
Robert J. Sawyer, “An Amateur Space Telescope”, Sky & Telescope, Vol. 64, No. 2, pp. 127-129, August 1982
“Amateur Space Scope”, Astronomy, Vol. 10, No 9, p. 64, September 1982
“Amateur Space Telescope Nears Completion”, Astronomy, Vol. 12, No. 3, p. 60, March 1984