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Lee Hutchinson-July 10, 2014 3:45 PM UTC

Not every space story can have a Hollywood ending. Unfortunately, the situation with the newly resurrected ISEE-3 space probe seems to have a bittersweet ending. The International Sun-Earth Explorer 3 satellite has been dormant since 1998, but NASA allowed a crowd of “citizen scientists” to take over the spacecraft and consider sending it into a closer orbit. The organization called the ISEE-3 Restart Project has been posting regular updates on its blog, but the latest news is not optimistic at all-ISEE-3's thrusters are not operating as expected.

The detector uses small single-element rockets for attitude and translation (that is, turning and moving); the working principle of these thrusters is to inject some toxic hydrazine fuel into a propulsion chamber coated with a catalyst. The hydrazine reacts very violently with the catalyst, and the resulting gas is discharged from the thrust nozzle, turning or moving the aircraft. The problem-this is the problem of any engine-is that you need a way to transfer fuel from the tank to the engine. For most rocket engines intended to operate in microgravity and vacuum, the simplest method is not to use a complicated pump, but to pressurize the fuel tank with a certain amount of non-reactive gas (nitrogen is the most common). When you need to start the engine, you can push in more nitrogen to squeeze the fuel out of the tank.

It seems that the nitrogen reserves of ISEE-3 have either been exhausted or have leaked into the void. Although the spacecraft was able to act in accordance with some of the commands sent to it during its rotation on July 3 and the trajectory correction maneuver on July 8, the scientists of the ISEE-3 restart project suspected that the initial motion of the spacecraft was the result of residual motion . The pressurized fuel in the propulsion system. The team has been troubleshooting the spacecraft remotely, and they believe that they have eliminated valve failures and other hardware issues that were the source of the failure (you think it is difficult to repair your parents’ email over the phone!).

According to a short blog post yesterday afternoon, the team will continue troubleshooting and expect to be able to collect some additional data on Friday. However, the prospects are definitely not good-if the spacecraft's trajectory cannot be changed, ISEE-3 will be far away from the earth in its slightly elliptical heliocentric orbit (the probe also has a small chance of hitting the moon).

The plan to restart the project is to try to continue to communicate with the probe and extract data from its still-operating scientific instruments if feasible, but NASAWatch editor Genesis pointed out that about three months later, the spacecraft is too far away from the earth. Effective communication. The orbit of ISEE-3 is close to that of the earth, but it is different enough to separate the two celestial bodies. Then, it will take decades before the probe is close enough to the earth to communicate again.

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