Astronomers have found more than 6.000 planets orbiting other stars in recent years, but few of these are considered potentially habitable. Now that new telescopes on the ground and in space are able to detect them, scientists are scanning their atmospheres for signs of life: current technology, however, does not allow to observe objects around stars similar to the Sun.
That's why the next big scientific goal is to send a spacecraft with a “robot geologist” on an epic mission to explore the surface of an exoplanet. It's not a movie, gentlemen: welcome to the RIGEL project.
A thousand years on the road
Even if we chose the closest star to the Sun, Tau Ceti, a spacecraft with current technology would take about 1000 years to reach it. This doesn't seem like an obstacle for the project RIGEL (Robotic Interstellar GEological Probe). Philip Horzempa, planetary scientist, has recently published a white paper, I link it here, which details this ambitious long-term mission.
Designed to land on an exoplanet and explore its surface, the RIGEL project will not be easy, but the document highlights that the enormous engineering challenge it presents is one reason why the mission should be launched as soon as possible. “For the first time in history, an Earth explorer will be able to walk on the surface of an alien planet,” we read in the paper, even if it will be a machine, a “geologist avatar” representing humanity. Did I really say “Avatar”? Well, well. But tell me it doesn't remind you of the plot at all, come on.
Give that geologist robot a ship!
The plan is to visit a planet in the Tau Ceti system, about 10 light years away. It is believed to be the closest system to include a temperate rocky planet similar to Earth or Mars, although more research is needed to confirm this. The engineering challenge is to increase the speed of the spacecraft beyond what is currently possible. It would need to reach 2.000 miles/3.200 km per second, just over 1% of the speed of light.
Quite complicated if you consider that the spaceship New Horizons nuclear-powered, the fastest ever launched from Earth, reached speeds of 10 miles/16 km per second. It flew by Pluto in 2015 and is now in the distant Kuiper belt.
“Achieving the right speed will require a focused engineering effort,” admits Horzempa. “It would certainly have to be a superlight spacecraft, and probably use shock waves from the thermonuclear explosion to reach the incredible speeds needed.” And slow down, I add, when it comes to getting there.
It's not the only challenge to face
Maintaining contact with the spacecraft for many centuries after it leaves the solar system will also be a huge challenge. It takes seven minutes to send a signal to Mars. Tau Ceti is a million times further away. Horzempa suggests considering high-bandwidth laser communications, which will soon be tested on NASA's Psyche mission, scheduled for 2026. However, because to keep the systems intact the spacecraft would have to "hibernate" for much of the journey , it would be convenient to communicate with Earth only every 20 years.
And here we come to the other challenges: first of all that of "hibernating" the robot geologist's house for many years, as mentioned. Or build power systems capable of functioning for 1.000 years, or shields capable of withstanding the impacts that would occur in the transition phase between and the system hosting the star Tau Ceti.
Can we cope with current knowledge?
Ongoing NASA missions could contribute to the RIGEL project, according to the paper, for a sort of “dress rehearsal.” The Mars Exploration Program it could develop new rovers also with a view to a thousand-year journey. And a preparatory mission could test the geologist robot on Mars: for NASA it would "only" be a matter of creating something that enters Martian orbit, identifies a landing site, arrives and explores the surface completely autonomously for at least a couple of years .
All this, Horzempa says, with an initial plan to be developed by 2029.
Robot geologist on an alien planet: a new, gigantic Apollo program.
I admit that I frowned several times when I read Horzempa's plan: an epic space race, but on a multi-century basis. But it's the only way to explore exoplanets. There is no “magic” solution to this problem: interstellar travel requires this time.
One generation is not enough, many are needed. For this reason, whether it is RIGEL or another project, if we want to leave a spatial legacy for future generations we must do this too.
Can't wait to see you go, geologist in my boots.
