NASA is reviewing 12 different proposals for an uncrewed mission to explore the solar system sometime in the next decade. There’s a platter of options and each one allows the space agency to focus on a patch of space we know little about.

Late last year, when NASA put out its initial call for the proposals under its New Frontiers program, it was looking for missions around six different themes:

  • Comet Surface Sample Return
  • Lunar South Pole-Aitken Basin Sample Return
  • Ocean Worlds (Titan and/or Enceladus)
  • Saturn Probe
  • Trojan Tour and Rendezvous
  • Venus In Situ Explorer

Each theme essentially takes a probe to a unique celestial body in the solar system for an extensive study of the geology, climate, chemical spectral, and other unique traits of each world.

Some proposals involve attempting a landing for a more in-depth study, while others are simply flybys. Some will look for signs of aliens, while others might be more relevant to fleshing out potential applications relevant to the expansion of the human species into space. Others still are are primarily focused on scientific investigation.

NASA is aiming to select one of the 12 proposals for flight in about two years, and wants to build and launch the mission by the mid-2020s.

We have no idea what the proposals entail as of yet (we’ve reached out to NASA to get some more detail, and we’ll update if the agency responds to us), but we know they must correspond to one of the six different themes. There are key advantages and disadvantages to each one. Below’s a quick-and-dirty breakdown ranked by least to most intriguing.

Waxing Gibbous Moon
Should we grab more rocks from the moon?

6. Lunar South Pole-Aitken Basin Sample Return

This type of mission is easily the dullest. There are many parts of the moon that remain unexplored, but by and large, it’s basically a dry, lifeless wasteland. The only real purpose a trip to the moon’s South Pole would serve is to help us figure out if that region of the rock contains any kind of unique resources worth mining in the future. The prognosis of that is kind of grim, given that we’ve been studying moon rock samples since Apollo 11 — but hey, we might find something new.

This mission would also be a pretty easy and useful demonstration of how to perfect sample return missions for future exploration to other worlds. Right now we don’t have a useful method for delivering rocks from Mars or other worlds back to Earth very easily — and this mission could help us fine-tune the process into something that can be easily executed.

Saturn on 28 nov, 2016 (red grn bl uv)
Another deep dive into Saturn?

5. Saturn Probe

The Cassini probe is already finalizing its last days zipping around the Saturnian system, but the mission was simply the beginning of what will surely be a long unraveling of one of the most exotic regions of the solar system. A new Saturn probe would pick up where Cassini left off and help us to better understand Saturn the same way the Juno spacecraft is allowing scientists to peel back the layers of Jupiter and illustrate what lies beneath the gorgeous strips of gas and dust.

And yet, a probe that studies Saturn is still just a mission with a science focus — and has little relevance to human exploration itself. Yes, it would be great to learn more about Saturn, but whatever tangible benefits we gain probably won’t come to fruition for at least a few more generations.

venus
What secrets is Venus hiding under that thick toxic atmosphere?

4. Venus In Situ Explorer

Venus is a tough cookie to study. It’s a world of staggeringly hot temperatures, unbearable pressures, and a toxic atmosphere rivaled by very few places in the universe. And of course, all of that only serves to pique the curiosity of the world’s scientists and prod them to find a way to directly study the planet one way or another. After all, Venus may have looked a lot like Earth a long time ago.

But that’s the key phrase: “may have.” It doesn’t anymore, and there’s no question humans will not be trudging out to the second rock from the sun and looking to establish a colony there anytime soon. A mission to Venus would be akin to an archeological dig: a fascinating dive into an ancient history which serves little purpose in helping the species in the near future.

Comet 67P on 26 February - NAVCAM
Comet 67P/Churyumov-Gerasimenko, imaged by the ESA Rosetta probe. 

3. Comet Surface Sample Return

Comets are a hell of a lot more than just balls of ice and rock whirring around. They may be the universe’s way of shipping the ingredients necessary to start life around to parts far away. Maybe that’s how life on Earth started? A sample return for a comet might definitely prove whether it’s possible for life to be seeded to other worlds.

This would also be an insanely difficult endeavor. ESA’s Rosetta mission already tried to put a lander on a comet once just a couple of years ago, and it didn’t go very well. NASA would need to put an insane amount of work into trying to accomplish something that already has a high probability of failing. It’s not exactly a guarantee of making the most of taxpayers’ dollars.

Asteroid Mining
Studying the Trojans might be a boon for asteroid mining.

2. Trojan Tour and Rendezvous

The Trojans are a curious group of asteroids trapped in specific orbits around various planets in the solar system. A mission to one or more of them would essentially offer a better study into how these little buggers ended up in such a strange position, and potentially serve as a way to figure out if we might be able to make use of them in the long run, probably as potential places in space to mine for resources. Several companies are making serious moves to make asteroid mining real by next decade, and a Trojan mission would put NASA ahead.

But of course, the Trojans aren’t easy to get to, nor is there any guarantee they’ll possess anything worthwhile for humans. A tour and rendezvous with the Trojans is more like a scouting mission than anything else, proving out the viability of deep space transport architecture and giving us some clues as to what we might want to look for when it comes to near-Earth objects. That’s about it.

Titan October 2014
This image taken by the Cassini spacecraft allows us to view Titan above and below its atmosphere. 

1. Ocean Worlds (Titan and/or Enceladus)

This is the hot tamale for a New Frontiers mission, especially given the hype launched by the agency’s latest findings of the potential for ocean worlds like Jupiter’s moon Europa to be habitable to some extreme forms of life. Saturnian moons Titan and Enceladus possess similar potentials, and a mission focused on either place would ostensibly be tasked with a main objective to look for extraterrestrial life.

So what are the downsides? Well, it doesn’t really seem as though there are any. Most scientists are on board with studying more ocean worlds — and have been clamoring to do so for a while. Perhaps the only real negative is that with NASA already revving up a mission to Europa, going to Titan or Enceladus might be redundant. But these worlds aren’t the same. A subsurface ocean for one could be radically different for another — and that also means the potential for life varies as well.

Photos via Flickr / MarkGregory007, Flickr / 2di7 & titanio44, Getty Images / Handout, Flickr / europeanspaceagency, Flickr / BlackBirdCD, Flickr / Val Klavans, Flickr / blueforce4116