No more than a week ago, it was announced that Voyager 1 had left the heliosphere and was in the interstellar space. Unfortunately, on this occasion, we were reminded of a rather unpleasant fact – Voyager’s success, or indeed any success in space exploration, may prove impossible to replicate, because the problem is the fuel supplying space probes, or rather its … lack.
The original goal of the Voyager spacecraft was to investigate Jupiter and Saturn, but after success, it was decided to extend the mission to study the remaining planets of the solar system and then interstellar space. The place where the heliosphere ends, and the interstellar space begins, is quite contractual and therefore some researchers claim that the probe crossed the border a year ago.
Voyager 1 is currently about 19 billion kilometers from the sun, the fastest moving object we have ever built, and the radio signal takes up to 17 hours to reach the Earth. Sending the probe would not have been possible without the fuel the probe was powered on. And it’s plutonium-238, whose reserves are at the finish.
Voyager and other space exploration probes, such as Galileo or Cassini, and even the Martian Curiosity Mars rover, are powered by radioisotope thermoelectric generators in which fuel is plutonium-238. At present, this is the only known type of space vehicle power for such long missions. Solar panels are too inefficient, and they lose value as they get away from the sun, chemical batteries do not last long enough, and nuclear reactors are too heavy to be able to reach their orbit.
Plutonium-238 is a radioactive isotope (one of fifteen isotopes of plutonium), which releases large amounts of heat during its disintegration. It is heat that is converted into electricity, powered by spaceships.
The biggest problem is that after the end of the Cold War, this element ceased to be produced and uses only stockpiles. Its manufacturing process is closely linked to nuclear weapons technology.
Since 1993, the entire platoon used by the US was purchased from Russia, but in 2009 Americans were denied the sale of another portion of fuel. According to unofficial information, the US in 2005 had 87 pounds of element (about 40 kg), only 1/3 of which was dedicated to NASA. The rest was held as a reserve for underwater spy devices.
Researchers estimate that NASA currently has no more than 36 pounds of plutonium in its hands – so much does not give the Agency too much room to maneuver. Researchers estimate that it would only be enough for one major mission. And yes it is planned. In the near future, a probe will be sent into the cosmos to examine one of the moons of Jupiter – Europe. It is predicted that under liquid ice cover liquid water may be present, but to search for signs of life the probe would need even 47 pounds of plutonium. Another mission, which is already in its advanced stage, is the planned launch of the Curiosity twin on the Red Planet. He will also need fuel for exploration of Mars.
Researchers are naturally aware of the shortage of fuel and have repeatedly addressed Congress asking them to resume production of the plutonium-238. Last year the US government approved such a program. $ 10 million will be spent annually on the production of plutonium-238 in the Tennessee nuclear reactor. But scientists say it’s just a drop in the sea of need, and with such funding it will produce only a few pounds of isotope a year to keep the space exploration program at a fairly low level. All the more serious and more ambitious programs have already been stopped and will not be restored very soon.