Voyager 1 & 2 have been operating for nearly forty years so we can obviously operate a space probe for at least that long.

Could we build and power one that could operate for a century or longer.

Would it be of any benefit to land a probe on a long period comet and use it as a base of operations.

I don’t think Voyager 1 & 2 are manoeuvrable anymore??

Peak Warming Man said:

I don’t think Voyager 1 & 2 are manoeuvrable anymore??

I couldn’t find anything about manoeuvrability but apparently they will have enough power to operate until 2025

It seems that they use plutonium-238 as a major component in deep space power supplies, radioactive decay providing heat. So it would just be a matter of having more onboard to last longer, keeping in mind the half life is <90 years. I also saw some suggestion that Pu 238 supplies are currently running low so there may not be much available for an extended mission…

Americium-241 is a potential candidate isotope with a longer half-life than 238Pu: 241Am has a half-life of 432 years and could hypothetically power a device for centuries. However, the power density of 241Am is only 1/4 that of 238Pu, and 241Am produces more penetrating radiation through decay chain products than 238Pu and needs more shielding. Even so, its shielding requirements in an RTG are the second lowest of all possible isotopes: only 238Pu requires less. With a current global shortage of 238Pu, 241Am is being studied as RTG fuel by ESA. An advantage over 238Pu is that it is produced as nuclear waste and is nearly isotopically pure. Prototype designs of 241Am RTGs expect 2-2.2 We/kg for 5-50 We RTGs design, putting 241Am RTGs at parity with 238Pu RTGs within that power range.

furious said:

Americium-241 is a potential candidate isotope with a longer half-life than 238Pu: 241Am has a half-life of 432 years and could hypothetically power a device for centuries. However, the power density of 241Am is only 1/4 that of 238Pu, and 241Am produces more penetrating radiation through decay chain products than 238Pu and needs more shielding. Even so, its shielding requirements in an RTG are the second lowest of all possible isotopes: only 238Pu requires less. With a current global shortage of 238Pu, 241Am is being studied as RTG fuel by ESA. An advantage over 238Pu is that it is produced as nuclear waste and is nearly isotopically pure. Prototype designs of 241Am RTGs expect 2-2.2 We/kg for 5-50 We RTGs design, putting 241Am RTGs at parity with 238Pu RTGs within that power range.

Interesting concept for a long term probe

Cymek said:

Voyager 1 & 2 have been operating for nearly forty years so we can obviously operate a space probe for at least that long.

Could we build and power one that could operate for a century or longer.

Would it be of any benefit to land a probe on a long period comet and use it as a base of operations.

As furious says, Americium-241 is a good option with a half live of 432 years.

For a very long mission, Carbon-14 with a half life of 5,730 years and Plutonium-240 with a half life of 6,563 years are always options. Both are readily available.

> Would it be of any benefit to land a probe on a long period comet and use it as a base of operations.

People keep trying to tell me “no”, but the real answer is “yes”. All you need to do is harpoon the comet like a whale, then slowly reel it in. In that way you don’t have to match velocities at the meeting point, and that saves you at least 50% in fuel cost. I’d prefer to harpoon a non-periodic comet, but getting to the rendezvous fast enough would be a challenge.

Developing a long term power source is probably not the big stopper. You could build an RTG to cook away for tens of thousands of years.

Can you build electronic components to last that long? Can you build RAM that can be written and read tens of thousands of years from now despite cosmic radiation?

dv said:

Developing a long term power source is probably not the big stopper. You could build an RTG to cook away for tens of thousands of years.

Can you build electronic components to last that long? Can you build RAM that can be written and read tens of thousands of years from now despite cosmic radiation?

Hmm. Cosmic radiation can be bad. Cumulative damage.

On the other hand, often computer chips are exposed to the interior of a nuclear reactor in order to make them better.

> Can you build RAM that can be written and read tens of thousands of years from now despite cosmic radiation?

I think so. The bigger the element, the more resistant it is to cosmic ray damage. There are also other techniques.

https://en.m.wikipedia.org/wiki/Radiation_hardening

Physical hardening​ Vs logical hardening.

Hardened chips are often manufactured on insulating substrates instead of the usual semiconductor wafers. Silicon on insulator (SOI) and sapphire (SOS) are commonly used. While normal commercial-grade chips can withstand between 50 and 100 gray (5 and 10 krad), space-grade SOI and SOS chips can survive doses many orders of magnitude greater. At one time many 4000 series chips were available in radiation-hardened versions (RadHard).

Bipolar integrated circuits generally have higher radiation tolerance than CMOS circuits. The low-power Schottky (LS) 5400 series can withstand 1000 krad, and many ECL devices can withstand 10 000 krad.

Magnetoresistive RAM, or MRAM, is considered a likely candidate to provide radiation hardened, rewritable, non-volatile conductor memory. Physical principles and early tests suggest that MRAM is not susceptible to ionization-induced data loss.

Shielding the package against radioactivity, to reduce exposure of the bare device.

Capacitor-based DRAM is often replaced by more rugged (but larger, and more expensive) SRAM.

Choice of substrate with wide band gap, which gives it higher tolerance to deep-level defects; e.g. silicon carbide or gallium nitride.

Shielding the chips themselves by use of depleted boron (consisting only of isotope boron-11) in the borophosphosilicate glass passivation layer protecting the chips, as boron-10 readily captures neutrons and undergoes alpha decay (see soft error).

Logical

Error correcting memory uses additional parity bits to check for and possibly correct corrupted data. Since radiation effects damage the memory content even when the system is not accessing the RAM, a “scrubber” circuit must continuously sweep the RAM.

Redundant elements can be used at the system level. Three separate microprocessor boards may independently compute an answer to a calculation and compare their answers.

Redundant elements may be used at the circuit level. A single bit may be replaced with three bits and separate “voting logic” for each bit to continuously determine its result. This increases area of a chip design by a factor of 5.