NASA’s ‘mission impossible’ program supports interstellar flight study – 01/21/2024 – Messenger Sideral

One of the most interesting readings on the NASA website for those who like science fiction is the selection of projects to be supported by the Niac program, an acronym in English for NASA’s Advanced Innovative Concepts. He funds small studies (at US$175,000 per year) with ideas for the future. In the 2024 edition, there’s a little bit of everything, from flying into the rarefied atmosphere of Mars to collecting samples from the scorching hell of Venus. But the boldest proposal has to do with the (almost) impossible challenge of an interstellar flight.

The problem is simple to understand – and difficult to solve. A spacecraft sent into interstellar space with conventional chemical propulsion (good old rockets) could not reach the closest star to the Sun, Proxima Centauri, before tens of thousands of years had passed. To accomplish the task of overcoming 4.2 light-years of distance in a reasonable time, it is necessary to reach relativistic speeds, that is, speeds that represent a significant fraction of c, the speed of light.

Thomas Eubanks, from the Florida-based company Space Initiatives, was one of those awarded by the program this year with the proposal to send a swarm of laser-driven mini space sailboats. The idea is to launch thousands of these small ships into orbit, weighing a few grams each, and then use a laser cannon to accelerate them to up to 0.2c, 20% of the speed of light. In the proposal, he imagines that such a mission will be carried out in the second half of the 21st century.

Why not now? Because he would need a laser with a power of 100 gigawatts, which doesn’t exist yet, thousands of mini solar sailboats capable of resisting the launch, something that doesn’t exist yet, and what he calls “terrestrial light buckets” (essentially telescope mirrors ) with an area of ​​1 km2, which also do not exist.

And why a swarm of thousands of ships, instead of just one? First, to maintain redundancy – even if some are destroyed by collisions or defects along the way, many will survive the crossing. Secondly, because such a small ship alone would not be able to maintain contact with Earth at interstellar distances. The solution would be to put them all in synchronism, each one firing its tiny laser in our direction, so that the collective shot becomes detectable (with the “buckets of light”), transmitting the data to Earth.

A third reason: with a swarm of mini-ships spread out, even with the uncertainties about the exact position of the planet Proxima b, which orbits that star, some will have to pass close to it to take good images.

This whole complication shows how challenging it is to make interstellar flights with technologies close to current ones (even if extrapolated to a higher level). But it’s also charming that, even with all the limitations, we can now dream of missions like this. It is very likely that this proposal will never go beyond the conceptual study phase. But it also doesn’t hurt to remember that Niac has financed other bold ideas in the past that ended up becoming reality, such as a Martian helicopter and nanosatellites in interplanetary missions.

This column is published on Mondays in print, in Folha Corrida.

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