Time is money, also when it comes to traveling into space. However, current aircraft propulsion mechanisms are not prepared to send us beyond the solar system. The possibility of doing so using lasers has been investigated. However, despite everything that this tool offers us, the mechanism has some limitations. Now, however, a very interesting alternative has been presented, with which a kind of tiny and super-fast bullets are used, which push the spacecraft to its destination.
It sounds like science fiction, but a group of scientists at the University of California, Los Angeles (UCLA) is already investigating the possibility of doing it. According to them, in this way they could be able to launch a one-ton spacecraft to the edge of the solar system in just 20 years. This is very little, if we take into account that with current propulsion methods it would take between 19,000 and 81,000 years. Too much for there to be someone prepared to pick up the baton from those who launched it.
The proposal is so interesting that has been one of those selected in 2023 by NASA in its Innovative Advanced Concepts program. With it, more than $175,000 in grants have been awarded, so the project, while ambitious, has a good budget to start with.
Current methods of traveling into space
Traveling into space, beyond the solar system, has a great limitation, based on something known as the rocket equation. He explained it to Universe Today one of those responsible for this project, Artur Davoyan:
“All current spacecraft and rockets fly by expanding fuel. The faster the fuel is dumped, the more efficient the rocket is. However, there is a limited amount of fuel that we can take on board. As a result, the speed to which a spacecraft can be accelerated is limited. This fundamental limit is dictated by the rocket equation.
Artur Davoyan, Assistant Professor of Mechanical and Aerospace Engineering at the University of California, Los Angeles (UCLA).
By limiting the speed of the rocket so much, traveling into space becomes a challenge when the distances are too great. Also, if the load on the spacecraft is very large, that speed must be further reduced. For all this, space exploration is focused above all on the solar system.
Currently, the spacecraft that have gone furthest are Voyager 1 and 2. However, these are only 159 and 132 AU from the Sun. This is a lot, but not as far as the heliopause, which is located at 500 AU and marks the border between the solar system and interstellar space.
Nuclear propulsion to push a spacecraft
In recent years, attempts have been made to solve this problem through nuclear propulsion. Is can be of two types.
On the one hand, nuclear thermal propulsion is based on the use of a fission reactor to drive the spacecraft. In this, heat from the decay reactions of uranium and deuterium is used to heat liquid hydrogen. Thus, it passes into its gaseous state and is channeled through a nozzle to generate thrust.
On the other hand, with electric nuclear propulsion the same reactor is used, but the heat is used to obtain electrical energy with which an engine that is responsible for thrust is fed.
Several space agencies have begun to carry out the first experiments in this direction. However, it remains a poor option for space travel beyond the solar system.
Artur Davoyan/University of California
Ultra-fast bullets to travel to space
To solve all the above problems, scientists have begun to study the option of traveling into space with the help of laser beams. These could push the spacecraft by radiation pressure, so that fuel would not be needed. In this way, speeds close to that of light could be reached. However, there is a problem, as the lasers diverge over long distances.
So even if you could get a faster spaceship, you still couldn’t use that speed to go further.
To solve this problem, Davoyan’s team proposes to continue using laser beams, but add a path of small bullets, which would be responsible for pushing the spacecraft. Those bullets would be very small pellets, which would be accelerated to very high speeds by laser ablation. That is, a laser would be used to heat them so that they absorbed so much energy that the material would end up turning directly into a gas. This would generate momentum that would push the spacecraft forward.
These bullets are heavier than the photons in a normal laser beam, so a higher boost would be obtained. In addition, they do not diverge when the distance is increased, so one could travel in space beyond the solar system. And another big advantage is that a bigger load could be driven. Other concept designs were on the order of grams or a few kilos, while they talk about powering a one-ton spacecraft.
Logically, there is still a lot to investigate, but this could be a revolutionary tool in the space race. We have already seen how to travel faster, now it remains to travel further. Much, much further.