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Pioneer 10 Still Running After 30 years
evilempireinc writes "According to this article in Scientific American, Pioneer 10 is still functioning 30 years after it was launched in 1972, and is still sending back scientific data. The article mentions that two other old space craft, Voyager, and IMP-8 are still functioning after over 20 years as well due to overbuilt construction and redundant systems. Can't help but wonder if the present generation of "faster, better, cheaper" probes will ever live this long though."
Anyone who went to elementary school in the 70's ought to remember the cafeteria milk cartons with little factoids about Pioneer, Voyager, and a bunch of other spacecraft. I wonder if anyone has pictures of those old things?
[2002-07-23]
Pioneer 10
Distance from Sun (AU) 80.858
Speed relative to Sun (km/s) 12.255
Speed relative to Sun (AU/year) 2.585
Ecliptic Latitude 3.0
Declination (J2000) 25.78
Right Ascension (J2000) 5.012 hrs
One-way light time (hours) 11.31
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. Or that it is real stable because the OS crashes only once a day.
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This graphic from The Telegraph article shows where Pioneer 10 is (outside of our Solar System). It also shows pictures it took of Jupiter (1973), Saturn (1979) and Pluto (1983). It has been almost 20 years since it left our Solar System. Apparently it is heading towards the "Eye" of the Taurus Bull constellation, and will take 2 million years to reach it. however it is slowing down by some "mysterious" force.
I seriously question the long-term of any semiconductor electronics built today. No, there are no moving parts - except the electrons and any atoms they may knock about as they scurry on their way from source to drain and through the wires.
Shipping reliable semiconductors has always been a lifetime issue. There is a "bathtub curve" of failures, with a higher number of early fallout, then a very reliable main lifetime, then failures rise again at wearout. Wearout happens through mechanisms like electromigration, where the electrons physically knock the metalization atoms out of place. In addition, all of the hot process steps like diffusion continue to happen, just at much slower rates. High reliability semiconductors are "burned in", run at higher temperatures and voltages than normal, to force them past that early fallout and throw those parts away.
So what does this mean to space electronics? First, radiation just doesn't help. You can design rad-hard, but the crystal lattice is still taking damage, and it's cumulative. The low temperature helps to slow down wearout mechanisms.
But the big problem is modern technology. The smaller geometries will simply wear out faster. Finer wires are more subject to electromigration, though using copper is an improvement because the atoms are heavier than aluminum. But gates are thinner, as are diffusions and spacings, non of which helps long life. When designing a burn-in regimen, it's getting tougher to get past early failures without approaching wearout. While frequency can be reduced to increase lifetime, scaling voltage down is getting tougher, because we're running darned close to minimums, already.
One of my pet thoughts is the idea of electronics for a multi-generation starship. Other than slowing it down, stopping as much as possible, reducing voltages, etc, it's a tough problem. Maybe the best way is to scrape the bargain bins for old technology.
The living have better things to do than to continue hating the dead.
Actually, Pioneer 10 and 11 and Voyager 1 and 2 have both cleared the solar system... well, depending on what you define as the solar system.
p ioneer/PNhome.html).
Pioneer 10 crossed the orbit of Neptune and passed beyond the (at the time) furthest orbiting planet on June 13, 1983 (see this page). It hasn't passed the heliopause yet (distance where the solar wind ceases), at least not that anyone can determine.
Pioneer 10 is not the probe furthest from the sun, however. Apparantly that honor goes to Voyager 1, which is moving faster and exceeded Pioneer 10's heliocentric distance on Feb 17, 1998, but it's still well over 7 billion miles away. (see http://spaceprojects.arc.nasa.gov/Space_Projects/
One interesting thing I found while looking for this is that only Pioneer 10 is moving in the opposite direction from our solar system (relative to the galactic core). Voyager 1 & 2, as well as Pioneer 11 are moving "in front of" us, while Pioneer 10 is moving the opposite direction. This could result in some really useful information about the edges of the solar system -- except that apparantly Pioneer 10's power system is going to run out of juice in a few years (solar powered I guess - the W/m^2 will probably be too low to power the probe at that point).
And no, we're not getting pictures of Neptune or Pluto. You determine these things at time of launch -- we've been doing astronomical calculations for a few hundred years and know where the planets are going to be far ahead of time. Pioneer 10 wasn't scheduled to make a flyby of anything but Jupiter because the orbits were wrong.
And yes, it is still sending back data. As is Pioneer 6, which is still orbiting the sun at about 74 million miles (inside the Earth's orbit). But, like I said, apparantly that's not going to be much longer for Pioneer 10. Shame... but one heck of a legacy to its designers. And just think - in a couple million years we'll be able to pick it up in the vicinity of Aldebaran.
Actually, that was Voyager VI. Except we were told of only two: Voyager I and Voyager II (actually launched first, if I recall correctly, due to a faster trajectory.) Hmmm... Wonder if the Men in Black were involved in that cover-up. ;)
i am a soviet space shuttle
(solar powered I guess - the W/m^2 will probably be too low to power the probe at that point).
Nope. Actually, solar panels are not a practical means of powering a spacecraft beyond the asteroid belt, and these probes go far, far beyond that.
Pioneer 10 and 11, Voyagers 1 and 2, Ulysses, Galileo, and Cassini (to name many of the "big" and famous probes that are out there right now) are all nuclear powered. They carry radioisotope thermoelectric generators (RTGs) that carry plutonium as a fuel source. Surprisingly (?), the Viking I and II landers that touched down on Mars in 1976 are also nuclear-powered.
The probes are gradually dying because their plutonium fuel is running out, not because the sun is fading away. At the distances at which many of these probes travel, the Sun appears (from their location) simply as a bright start among many other stars.
i am a soviet space shuttle
This could result in some really useful information about the edges of the solar system -- except that apparantly Pioneer 10's power system is going to run out of juice in a few years (solar powered I guess - the W/m^2 will probably be too low to power the probe at that point).
The Pioneer 10 & 11 probes are not solar powered. They use RTG (radiothermal generation) power sources, which are hot lumps of radioactive material and the heat is converted into electricity. Solar power would be far too weak even at Jupiter or Saturn, much less at the distances that Pioneer 10 & 11 are at.
The radioactive source is continually decaying, so it will lose power over time.
NASA still publishes semi-regular status reports on both Voyagers here.
--
THE GOOD HUMOR MAN CAN ONLY BE PUSHED SO FAR
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Anyway, Voyager 1 appears to be just short of 8 billion miles from the sun rather than "well over 7" as mentioned below.
My post needs to be slightly corrected: the cause of the power loss is mostly due to aging of the thermal couple, not the decay of the radioactivity.
More information from Pioneer home page:
Electrical power is provided by four radioisotope thermoelectric generators (RTG), each providing 40 watts of power at launch. Two three-rod trusses, 120 degrees apart, project from the equipment compartment to deploy the RTG power sources about 10 feet from the center of the spacecraft. A third boom, 120 degrees from the others, projects from the experiments compartment and positions the helium vector magnetometer sensor 20 feet from the spacecraft center.
and from the FAQ
Question:Why does the RTG power decrease?
Answer: Power for the Pioneer 10 is generated by the Radioisotope Thermoelectric Generators (RTG's). Heat from the decay of the plutonium 238 isotope is converted by thermoelectric couples into electrical current. The electrical output depends on the hot junction temperature, the thermal path to the radiator fins, and the cold junction temperature. It is the degradation of the thermoelectric junction that has the major effect in decreasing the power output of the RTG. In the 30-year time scale operation of Pioneer 10, the 92 year half-life of the isotope does not appreciably affect the RTG operation. The nuclear decay heat will keep the hot junction temperature hot for many years but unfortunately will not be able to be converted into enough electricity to power the transmitter for much longer.
As an aside, this type of power source is behind the plutonium scare-mongering that surrounded Cassini.