Computers and memory, radios, cameras, light sensors, temperature sensors, accelerometers & gyros1, power supplies, power conditioners and converters and battery interfaces can all be put together with Commercial Off-The-Shelf or COTS components.

That doesn't necessarily meant they will work well together or individually in space.

Question: What was the first satellite built with mostly COTS electronics? How well did it work?

1MEMS accelerometers & gyros can be bought now but may not have been available when a potential answering-spacecraft was launched, so I've specified "most COTS electronics" above.

  • $\begingroup$ I've added the cubesat tag but I don't want to require a cubesat as an answer. Do we need a smallsat tag, or might we just include small satellites within the cubesat tag's usage guidance? $\endgroup$
    – uhoh
    Jan 26, 2021 at 15:46
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    $\begingroup$ It depends on what you mean by COTS. Does the RAD6000 count as COTS? If one was designing a satellite in the early 2000s that would have been the go-to computer. Or by COTS do you mean a computer one can buy at a local computer store? $\endgroup$ Jan 26, 2021 at 19:05
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    $\begingroup$ @DavidHammen references to COTS electronics in space are all over the internet, it's not my construct and I don't think I should dare to redefine it. I would assume that post 1996 RAD600s might be a stretch at $200k. Answers to How much more expensive are scientific instruments for space use? use the term COTS at length, so it seems to have some generally understood meaning already. $\endgroup$
    – uhoh
    Jan 27, 2021 at 0:28
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    $\begingroup$ I can't imagine anybody launching a spacecraft without having extensively tested whether or not its components will work well together. Of course, whether or not they will work well in space is a different question. $\endgroup$ Jan 27, 2021 at 2:34
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    $\begingroup$ this is probably your starting point en.wikipedia.org/wiki/AMSAT $\endgroup$
    – Puffin
    Mar 25, 2021 at 23:26

3 Answers 3


I think the satellite is the Telstar 1 satellite

It was launched in July 1962

Telstar 1 was a communications satellite launched by NASA. It was the satellite that allowed the first live broadcast of television images between the United States and Europe.

It remained active for only 7 months, much shorter service life than today's artificial satellites. Although it no longer works, it is still in Earth orbit.

A 53-meter terrestrial antenna manufactured by AT&T Corporation, located in Andover, Maine, was used for the transmissions between the U.S. and Europe. Built-in 1961, and used by Telstar 1, it was later used by Relay 1. Telstar 1 operated normally from launch until November 1962 when the radiation from the Starfish Prime detonation affected the command channel, which began to behave erratically. The satellite was continuously switched on to work around this problem. On November 23, 1962, the command channel stopped responding. On December 20, the satellite was successfully reactivated, and intermittent data were obtained until February 21, 1963, when the transmitter failed. The energy used by it was produced by 3,600 solar cells. The satellite relied on an active repeater and magnified signal strength by a factor of a hundred using a traveling wave tube amplifier (TWTA). Thirteen days after the launch, the first live broadcast of a television show between the United States and Europe took place

I found more about COTS and its history etc. on this website


TLDR Sputnik 1 / Explorer 1

Rationale: I believe the terms COTS and hi-rel have taken a while to take hold. If we take the assertions of the article linked to by RUNTIQ as correct then the significance is unstated but can be deduced from this sentence (end of 3rd para)

Telstar had become the first “victim” of radiation-induced electronic failure. Six other satellites were lost within the next seven months, and the earnest study of radiation effects in electronics became a top priority for engineers and scientists the world over.

The apparent implication is that the concept of having specially selected parts of space missions, specifically with respect to radiation tolerance, did not exist at the time of the Telstar 1 launch.

So if that is the inference then why choose Telstar 1? Surely all satellites prior to that time used commercially available parts because no other concept existed at that time. You may note I've generalised away from any special modern definition of COTS to just "commercially available". It might be better to say Explorer 1 rather than Sputnik 1 out of recognition that electronic parts in the Soviet Union may not have been considered "commercial" at all.

Obviously the concept of COTS has many dimensions, not limited just to radiation tolerance. However the twenty years prior to the Telstar 1 launch saw a great deal of evolution of transistor types and the idea of mass production hadn't been around for long. That all said, I'd be surprised if there wasn't already in existence a notion of procuring transistors of different quality, e.g. with respect to repeatable parameters and tolerance to high current and temperature.

Another aspect of this, which would help put an answer together, is when parts stress analysis began as a discipline, as this would very much inform the choice of component sources. My suspicion is this also began in the early '60s and I recall once seeing a paper on the topic dating from 1964 or so, though I can't find a link to it any more.


From the information on these websites 1, 2 & 3 (sorry but 3 is in Dutch - the electronic schematic diagrams in 2 & 3 match), the radio transmitter for Sputnik 1 used electronic tubes/valves, capacitors, variable capacitors and resistors. All "readily" available electronic components in 1957.

It appears the tubes used in the radio transmitter where unusual,

being a wire-ended design with all electrodes mounted on rods the length of the glass envelope. This design feature gave them a resistance to acceleration and vibration, making them suitable for use in aircraft, missiles, and rockets.

This gives the impression the tubes may have been military grade and not available for civilian purposes, unless they were available for use in civilian air craft.

  • 1
    $\begingroup$ This reminds me of my high school calculus teacher's warning about answering max/min questions; "Don't forget to check the endpoints!" Yes, I think that "...the first satellite built with mostly COTS electronics" is going to turn out to be "...the first satellite built..." :-) $\endgroup$
    – uhoh
    Jan 17, 2022 at 0:34
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    $\begingroup$ @uhoh: My understanding Sputnik 1 was very basic & it was a hurried design after Object D was rejected by Korolev apparently for being too heavy. With basic & hurried you get "what can we make out of what's available". $\endgroup$
    – Fred
    Jan 17, 2022 at 0:43

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