Three cheers for our space robots
Nasa’s New Horizons spacecraft, now exploring the vast region of our solar system beyond Neptune known as the Kuiper Belt, completed yet another trip full of superlatives: Recently, it celebrated its closest approach to Ultima Thule, the farthest object ever visited by spacecraft.
Ultima Thule is 1.6 billion kilometres past Pluto, more than 6.4b km from Earth, and radio signals take more than six hours to travel from the spacecraft back to Nasa’s receivers. At this distance, the sun is just the brightest star in sight, and the temperature is minus-234 degrees Celsius.
New Horizons, for which I serve as a member of the science team, is a prime example of the essence of robotic exploration. Space robots might not capture the imagination of the public as much as a person setting foot on the Moon. But today they are operating at the frontier of science. And so they deserve a moment for our gratitude.
We can design robots to survive long cruises and the extremes of radiation and temperature in space. And we can reprogram and repurpose them as new exploration opportunities arise.
Ultima Thule was not discovered until eight years after New Horizons was launched in 2006. The entire planning for the Ultima Thule encounter did not even begin until after New Horizons sped past Pluto in 2015.
The discovery of Ultima Thule allowed Nasa to take advantage of a healthy spacecraft in the outer solar system. Since it took nine years to get to Pluto, this placed an extremely capable observatory into previously unexplored regions.
Robots can also carry instruments that hugely extend the reach and sensitivity of our senses. Robots can be built cheaply and quickly as opportunities arise. New Horizons was designed, built, tested and launched in less than four years.
For spacecraft, this was fast because it was driven by a celestial free ride, the chance to borrow energy from an encounter with Jupiter that would accelerate New Horizons toward Pluto and cut five years off the trip.
Fundamentally, robots are about taking chances. Going into the unknown, doing it quickly and for modest investment, and discovering critical data in unexplored regions, is going to be risky. Robots do the risky exploration of new regions to pave the way for future explorers – either robots or humans.
Part of the success of the Apollo missions to the Moon was their robots. Nasa’s Lunar Orbiters mapped the Moon’s surface, Nasa’s Rangers got close-up views of the surface and helped perfect navigation skills, and Nasa’s Surveyors explored the surface and practised soft landings.
New Horizons continues its mission. Given the staggering distances, it will take almost two years for all the data collected during the short flyby of Ultima Thule to be sent back to Earth. During that time New Horizons will continue exploring the edge of the solar system by using its instruments to observe other Kuiper Belt objects too faint to be observed from Earth.
And that’s just one robot now exploring our solar system. The InSight lander that arrived on Mars last year is listening for ‘‘Marsquakes’’; the Osiris-Rex spacecraft is preparing to sample an asteroid; the Lunar Reconnaissance Orbiter is mapping our Moon; and the Juno probe is orbiting Jupiter.
This is what robots are good for: Going to the extremes of the solar system, coping with the extreme environments and providing the new views that continue to amaze.
Robots are operating at the frontier of science. And so they deserve a moment for our gratitude.