There are times when NASA really looks forward to finding nothing. It’s not that anyone was getting tired of seeing new planets, or that a null result would somehow save anyone the trouble of writing up their findings, especially considering the fact that scientists actually wrote 38 pages about how much nothing they found in the space around Pluto. Pluto of course has a sizable moon in Charon and a thin atmosphere, but importantly, when the New Horizons flew by in 2015, the spacecraft didn’t have to worry about dodging icy debris floating near the dwarf planet.
Hunting for hazards
We’ve never seen evidence that Pluto had rings of debris, but we never really got close enough to see all that much detail in before New Horizons arrived to give us a better look at. The large gas giants in the outer solar system, like Saturn and Neptune, all have rings made of rock and ice, suggesting a lot of loose objects are either floating through space or being created near those planets. If Pluto followed this trend, it could have meant that New Horizons would have been flying into a very dangerous situation, since even a small pebble could rip through the spacecraft at the relative speed of 36 thousand miles-per-hour. Just to be on the safe side, a mission control team nicknamed the “Crow’s Nest” was tasked with examining every new view of Pluto for any flicker of light in New Horizon’s path that might lead to trouble.
While flying over Pluto, scientists noticed that something else was relatively absent. The dwarf planet didn’t have nearly the number of impact craters that you might expect for an object that size. As the spacecraft passed over Pluto, teams kept looking for signs of debris that would now be silhouetted against light from the Sun. With that search also coming up empty handed, it suggests that the outer solar system is relatively empty, or at least consolidated in a way that you don’t find around our other planets.
Scanning for MU69’s scraps
Aside from hinting at larger trends about the composition of our solar system, there are practical reasons that this is good news for New Horizons. On January 1, 2019, the spacecraft will fly by its next target, an 18-mile-long object called 2014 MU69. With the clear skies found over Pluto, NASA hopes that there won’t be much to run into as New Horizons travels deeper into the Kuiper Belt. However, there’s a chance that MU69 might be actually be two objects in a tight orbit around each other, to the point of making physical contact. With this possible source of debris drawing closer, the Crow’s Nest team is back at work, looking out for tiny hazards before they become big problems.
Source: Why it’s good news that Pluto doesn’t have rings by Lisa Grossman, Science News