Another update on the reactivation of ISEE-3
The private effort to reactivate this 1970s science probe continues.
They attempted today to fire the thrusters to spin up the spacecraft as required, but were forced to abort. The information gained however tells them that they should be able to do what is necessary, including two major engine burns on June 30 and July 2, to put the spacecraft into its new orbit.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
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The private effort to reactivate this 1970s science probe continues.
They attempted today to fire the thrusters to spin up the spacecraft as required, but were forced to abort. The information gained however tells them that they should be able to do what is necessary, including two major engine burns on June 30 and July 2, to put the spacecraft into its new orbit.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
With the vacuum of space and the temperatures associated with space, I wonder what ageing affects these relics are prone to?
Ask the engineers who run the Voyager spacecraft.
By the 1970s engineers understood enough about interplanetary space to design spacecraft that could last a looooooong time in that environment. Thus, ISEE-3 has been successfully reactivated and apparently is responding predictably to commands. I am not surprised (though I am thrilled) and fully expect these non-NASA geeks to get the spacecraft back into operation.
Back when I was designing space instruments, we had to consider a lot of problems such as you mentioned, Joe. Materials were chosen that did not outgas in vacuum, instruments had to be tested at “survival” temperatures, and operating one instrument could not interfere with the operation of the other instruments — no electromagnetic radiation could escape, no “noise” could go back through power cables, etc.
Solar arrays (photo-voltaics) tend to degrade with exposure to ultraviolet light, and for commercial communications satellites, they are generally sized to have a 15-year “lifetime” before power delivered becomes too low for best operation of the spacecraft they are on (ISEE-3 is now more than twice that, but maybe it was designed to last longer). Different coefficients of expansion make for interesting designs to survive those “survival” temperatures (e.g. what material would you use to hold a glass lens at cryogenic temperatures?).
The industry learned, and still learns, a lot of lessons during testing (and, unfortunately, flight operation) of instruments and spacecraft, and the designs and missions are better for it. For example, modern Mars missions do far more and last much longer than the early missions of the 1960s and 1970s. With their Yutu lunar rover, the Chinese recently learned a few lessons the hard way, but they should do better next time.
I, too, am happy that ISEE-3 has lasted long enough to be “re-hijacked” by the “space pirate” team for a third mission.
Thank you for the reply, I tend too look at almost everything through the lens of a mechanic, however the temp ranges that I deal with are much smaller in range, I do have to deal with a vacuum on the low side to positive pressures of 400 psi with refrigerants, not quite the same as space. With regards to the mars rovers, I am astounded by their longevity, they are in my estimation a national treasure, however the reaction wheels that give ridgidity in space on space telescopes don’t seem to fare as well, is that a failure of lubrication or metallurgy? With regards to the voyager probes, the engineering must have been flawless as they are both still sending back information from intersteller space, the radios must have a good power supply.
Reaction wheels (sometimes called momentum wheels) depend upon bearings, and these wear out. Bearings are one of the main failure modes of hard drives (something else in the news lately). A spacecraft can experience small but constant torques from gravity gradients, especially in a planetary orbit, so the reaction wheels slowly spin up to high speed as they counteract those torques. Occasionally, the spacecraft operators will perform a reaction wheel spin-down maneuver by firing attitude control thrusters, and the wheels slow down as they counteract the torque created by the thrusters.
To answer the question, I haven’t analyzed reaction wheel or bearing failures, but the literature does not mention metallurgy as a cause of failure. Bearings tend to be well designed and should last long lives. Lubricants used for spaceflight or vacuum have very low outgassing/evaporation properties. I don’t know the degradation rates or modes of these lubricants; temperature could be one factor. Being in space, they don’t get gummed up by dust or other contaminants, and they are treated gently before launch, but poor handling seems to be one cause of failure. Bearings can develop flats on the balls, so they must be treated kindly. Bearing life is related to the inverse cube of running speed, so wear occurs much faster when the bearing is run faster. For every doubling of the bearing’s speed, the lifetime decreases by a factor of eight.
The final straw for Kepler was not so much a catastrophic failure of the bearing, but there was too much friction in the reaction wheel, from whatever cause, for the spacecraft to maintain the steady attitude it needed; it is hard to know whether that was a lubrication problem, a motor problem, or what.
The voyager power supply is a radioisotope thermoelectric generator. As the isotope decays, there is less power available, but it has been reliable. I suspect that, being unsure of radiation and other effects, they overdesigned the radio.