The Juno spacecraft, which arrived at Jupiter on July 4, is just one of many groundbreaking NASA missions to study the far reaches of our solar system. Other spacecraft have been deployed to study Pluto, Saturn, and even Ceres — a dwarf planet in the inner solar system. The information being gathered by these missions is completely changing the way we think about the composition of our solar system.
For one thing, scientists are pretty sure Pluto has an ocean.
“It's really extraordinary,” says Noah Hammond, a graduate student in the Department of Earth, Environmental and Planetary Sciences at Brown University.
“New Horizons flew past Pluto last year and saw images on the surface of these cracks — long tectonic cracks which were interpreted as extensional tectonic features when an ocean is slowly freezing…So what we did was we ran some calculations called thermal evolution models. Basically, we started with Pluto soon after it formed and we determined how quickly is it going to lose its heat over geologic time and we determined that Pluto probably still has an ocean today if those extensional features on the surface are present.”
The discovery of a likely ocean on Pluto has profound implications for the way we think about astrobiology and our solar system.
“One of the things that's really amazing about this result is that it looks like Pluto, like a lot of other icy bodies in our solar system have an ocean. And it certainly wasn't expected,” says Amy Barr Mlinar, a senior scientist at the Planetary Science Institute in Tucson.
“We didn't expect to find oceans in any of these icy bodies and now it looks like that's a really common feature for icy bodies … What's really interesting to me is a possibility that perhaps maybe other Kuiper Belt objects might have oceans. You know, oceans appear to be common features in the outer solar system and that's really surprising. That's definitely not something that we expected.”
Scientists are also hoping to figure out more about Jupiter, the biggest gaseous planet in our solar system. NASA is using the Juno orbiter to study Jupiter’s intensely powerful magnetosphere and auroras, zoom in on the gas giant’s wind patterns, and collect data that might finally help us determine whether, deep under the stormy gasses, there might be a solid core.
All the while, the spacecraft will be braving some of the strongest radiation in the solar system.
“There are fundamental questions like what is the core like, what is the magnetic field, like what are the clouds made of,” says NASA astrophysicist Michelle Thaller. “We actually don't know the size of Jupiter's core…is there some large rocky body underneath all of that, you know thousands and thousands of miles of gas and also liquid hydrogen? And in this case we're going to be getting so close to Jupiter that the gravity, the way the spacecraft responds to the gravity of Jupiter alone should tell us what the core is like. So that's never been done before.”
Other NASA scientists are training their sights on Ceres, a dwarf planet in our inner solar system. Last year the Dawn spacecraft arrived at Ceres and has been sending back data.
“Ceres is actually more than an asteroid,” says the deputy principal investigator for the NASA Dawn mission, Carol Raymond. “It's really designated a dwarf planet but it is a proto planetary remnant left over from the very first epoch of solar system formation.
"So when the small planetesimals were merging to form protoplanets and then those protoplanets were going on to form the planets that we know today, there are many many objects in the solar system that were probably similar to Ceres. But Ceres is the only object that we know of in the inner solar system which is a large primitive protoplanet. And so by going to Ceres and studying it, we’re able to look back in time and better understand what processes were going on during the time of the planets' formation.”
Ceres, like the other places NASA is studying, is continuing to surprise scientists.
“This is a geological world,” Carol Raymond says. “This is a small planet and what we're understanding now, based in part on the research that was published, is that this appears to be a geologically active world.”