What typically ends a satellite's life?

Question

It has been my opinion that running out of station keeping propellent is what usually ends a satellite's useful life. Is this true?

How much do different factors play in a satellite's lifespan? Some of the factors that occur to me: battery life, solar panel life, station keeping propellent supply, damage from radiation, damage from impact with debris.

I've been a supporter of NASA's or DARPA's efforts to robotically refuel and maintain satellites. However my enthusiasm may be based on erroneous assumptions.

Answer 1

Your question is

What typically ends a satellite's life?

and the answer is, as often, "it depends".

In the nominal case, lifetime is limited by fuel. All satellites need to perform orbit and attitude maneuvres using small rocket engines and are required to keep an end-of-life fuel reserve for de-orbiting, GEO stationary satellites are required to be moved at least 500 km above the GEO ring, and LEO satellites, as has been pointed out in another answer, are reequired to alter their orbit at end of life such that within 10 years the satellite is removed from orbit, which means slowing down the satellite which in turn decreases orbital height and therefore increasing airdrag, slowing down even more etc etc. Orbiting Infrared telescopes and similar satellites are limited by the amount of liquid Helium used to cool the optics and detectors.

Of course if a problem happens, it can be anything. Still, in case of a problem the satellite operator will do everything possible to keep the satellite functioning as good as possible, famous examples being Apollo 13 and the Space Telescope. From my own experience I know of a satellite which showed a problem very early on, after extensive experimenting on ground with the engineering model we managed to circumvent the problem and keep the satellite going for 4 times its nominal life. I also know of a satellite that failed because the orbit control system sprung a leak on initialisation, the satellite was stuck in its transfer orbit and burned up a few months later. Murphy always looks over your shoulder!

Answer 2

I have not heard of satellites that run out of station keeping fuel. This could be because they budget their fuel wisely and launch the necessary fuel for their mission lifetime so fuel is not a concern AFTER they launch.

As for satellites in orbit, there are regulations for designing your mission in regards to End of Life (EOL).
One EOL regulation is that GEO satellites are required to keep a certain amount of fuel on-board so that they can migrate their satellite out of the GEO belt before its EOL. For LEO, they must make sure their satellites de-orbits within 10 years after its mission life is over.

The end of life for some satellites that I have worked with or worked for include or have heard about:

1. Main Payload became non-operational (LEO satellite for remote sensing).
2. Improper Radiation shielding (LEO cube sat)
3. Improper orbit insertion from Launch Provider, it was fully operational but in the wrong orbit so primary mission is over, end of life. (GEO Communications satellite)
4. Satellite Collision Link to Collision Simulation video
5. Satellite stop communicating (Unknown reasons)
6. Battery stop holding charge

Answer 3

This depends on the type of satellite:

• Commercial satellites have a planned lifetime and a scheduled replacement. The owner generally has contracts to provide a service, and it's up to him to make sure the satellite is replaced before it reaches EOL.
• Scientific satellites are used until EOL or the money runs out, so you'll occasionally see a mission ending through catastrophic failure.

Satellites in geostationary orbit are generally limited by propellant. A refueling mission would increase the lifetime of the satellite.

Answer 4

Amateur Oscar 40 launched some years ago, was to provide a long period footprint for relay of Ham radio. Shortly after achieving orbit the ground controllers reported that there were anomalies in the telemetry data, then soon after ground control was lost. In discussion with the design team, and the other parties, it was determined that there had either been inadequate shielding, or damage to the shielding which allowed radiation to rapidly deteriorate the on board computers. The Radio links operated for some time after that, until the satellite moved too far out of orbit. It was an achievement which AMSAT, and the Amateur Radio world were proud to have taken part in.