NASA has selected two possible new missions to launch in the 2020s, one to a comet and one to Titan. The selection, however, has highlighted how many exciting destinations there are to go to in the Solar System, and how little money there is available to do them all.
The two finalists, announced yesterday and selected from a list of 12 possible missions, are part of NASA’s New Frontiers programme. After further development of the concepts in 2018, one of the missions will be selected in the spring of 2019 and awarded up to $850 million of funding.
This will be the fourth New Frontiers mission, the previous ones being the New Horizons mission to Pluto, the Juno mission to Jupiter, and the OSIRIS-REx mission to the asteroid Bennu, which will return a sample to Earth in 2023.
The first of the finalists is the Comet Astrobiology Exploration Sample Return (CAESAR). This would be a mission to return to Comet 67P/Churyumov-Gerasimenko, the comet that was visited by ESA’s Rosetta spacecraft.
“Comets are among the most scientifically important objects in the Solar System, but they're also among the most poorly understood," Steve Squyres, a researcher at Cornell University in New York, principal investigator for CAESAR, said at a news conference.
CAESAR, as its name suggests, would involve returning a sample from the comet to Earth. The sample would weigh at least 100 grams (3.5 ounces) and would be returned in 2038, telling us more about the comet’s origin and history. It’s an exciting mission for sure, and one that could tell us more about the origins of water and life on Earth.
“It’s good to go and build on the wonderful science we are doing with Rosetta,” Matt Taylor, ESA Rosetta project scientist, told IFLScience. “The cometary community is excited.”
The other mission is called Dragonfly, and it would involve sending a drone with eight rotors to the surface of Saturn’s moon Titan. It would fly over the surface and study dozens of sites, looking at the lakes and seas of liquid hydrocarbons on Titan like never before. Titan is the only place other than Earth with known bodies of liquid on its surface.
"Dragonfly would spend most of its time on the ground, but by being a rotorcraft, we're able to fly to multiple sites tens to hundreds of kilometers apart to be able to make these measurements in different geologic settings," Elizabeth Turtle from the Johns Hopkins Applied Physics Laboratory (APL) in Maryland, principal investigator for the mission, said at the conference.
This mission would be designed to launch in 2025, and arrive at Titan in 2034. It would explore the moon for a few years, using nuclear power to keep itself running, following up on the brief glimpse of the surface we got from Cassini's Huygens lander in 2005.
Alongside these two missions, NASA picked two others for further study to prepare them for possible future selection. One is the Venus In situ Composition Investigations (VICI), which would involve sending a lander to Venus to study the composition of its rocks.
The other is the Enceladus Life Signatures and Habitability (ELSAH) mission. This would look at ways to enable life detection on Saturn’s icy moon Enceladus, without contaminating the moon itself.
All of these missions are exciting in their own right. But the selection has once again highlighted the limited amount of funding in planetary exploration, with scientists bemoaning the fact we can only do one of these missions, not all of them.
There is an abundance of worlds in our Solar System of huge interest. Mars, of course, has plenty of proponents and missions, with NASA keen to "follow the water" here in its search for life.
Then we have the icy moons Enceladus, Europa, and all, each with the tantalizing possibilities of oceans beneath their surface. Venus, meanwhile, has been devoid of a proper NASA mission since 1989, leaving some to wonder if we are losing our window to make use of prior expertise.
NASA can only do so much with its limited budget. But there are just so many interesting destinations to explore in the Solar System. That we only get a handful of missions each decade is a travesty – the places we don’t get to visit just cry out even more.
With Trump recently doubling down on returning humans to the Moon, and VP Pence repeatedly saying the US needs to lead in space again, planetary science runs the risk of being left by the wayside. And it would be to the detriment of all.
Venus, in our Sun’s habitable zone, may offer clues as to what exoplanets might feasibly support life, itself being inhospitable for reasons that are not clear. Enceladus may have the key ingredients for life beneath its surface. Further out, Neptune and Uranus – visited only once, fleetingly, by Voyager 2 – give us the chance to study fascinating ice giants.
CAESAR and Dragonfly both offer incredible scientific returns. The smart money would be on CAESAR to be selected, given that it uses tried-and-tested technology. Many will bemoan the places left untouched, though. The Solar System is crying out for us to explore it – if only we had the money.