Soon the sun will set on NASA’s Dawn mission. Since being launched in 2007, Dawn has accomplished feats that no other probe has. Now, its days are numbered and we must pay homage.
Dawn’s mission has been extended several times, as so many of NASA’s brilliantly engineered probes have done. It has spent its time exploring the asteroid belt and orbiting the asteroid, Vesta and dwarf planet, Ceres; the two largest bodies in the belt (they make up 45% of the mass in the main belt). Dawn is special in a couple of ways. It is the only probe to visit and orbit two extraterrestrial bodies on its mission, and it is the only craft to ever orbit any body in the asteroid belt.
Vesta and Ceres were of particular interest to NASA, since they had been unexplored, and because “they function as time capsules, intact survivors of the earliest part of our history.” That’s according to nasa.gov. Dawn started its mission, powered by ion propulsion, orbiting Vesta in 2011 and 2012. During 14 months in orbit, Dawn studied Vesta from “surface to core”. In 2012, engineers steered Dawn out of orbit, and though the asteroid belt for over two years before putting it in orbit around Ceres, where it has been studying that world since 2015.
Every day, Dawn dives down to 22 miles above the surface of Ceres to get a good look. It has discovered incredible things there, like the chemistry of an ancient ocean, “bright spots” that may be salt deposits from that ocean, and abundant organic molecules. Organics like that are not proof of life, as they can be present for other reasons, but they are the building blocks of life on our planet. They certainly have scientists raising an eyebrow.
Dawn will soon run out of power needed to correct its position. And, because Ceres “has conditions of interest to scientists who study chemistry that leads to the development of life”, they don’t want to crash Dawn into the dwarf planet like they did with Cassini into Saturn a year ago. So, sometime in September or October, Dawn will quietly go to sleep and haunt Ceres in orbit for at least 20 years before crashing into its subject of adoration. It’s the poetry of a stalker. Maybe then we can finally start building Ceres Station, right The Expanse fans?!?
Good night, Dawn. And, thank you.