SpaceX’s launch early Thursday morning of a recycled rocket is a monumental step in creating more durable and economical missions to space. Rocket boosters, satellites, rovers, and scientific instruments will need to be more heavily girded against the elements with longer lifetimes and more uses should humanity succeed in exploring every planet or moon in the Solar System. For all the talk of Mars by the likes of NASA and SpaceX, the solar system has abundant unexplored territory.
Few places might have the known ingredients to support life, but that might be irrelevant to the cause of advancing space-faring science around the sun. Missions have been taken to places like Venus and the moons of Saturn, but we got a mere glimpse of what those worlds — in the case of Venus just a few hours. Even the realization Pluto’s collection of ice was extraordinarily diverse excited scientists. The fact several moons in our neighborhood have geological activity and heat generated not just from the sun but their host planets’ respective gravity is more of a reason to think complex molecules could develop and actually breed similar or alternative versions of carbon-based life on Earth.
Proposals abound to send longer-lasting spacecraft to those worlds and others, even with human crews. For now, several robotic missions have passed by the eyes of mission specialists and long-term schedule planners at places like NASA and other space agencies. ISRO is currently working on a follow-up mission to Mars, which is obviously not the focus of this list. These are just 10 of the most incredible but absolutely serious missions scientists have proposed for exploring our neck of the universal woods, with some in a very real hunt for research approval from the likes of NASA and funding approval from the United States Congress:
1. An ice drill to search for aquatic life on Europa
Following last year’s announcement NASA had confirmed volcanic water plumes on Jupiter’s moon of Europa, interest has spiked in the idea to explore the world. Europa constitutes the best candidate for discovering concurrent life on another body in the Solar System with its theoretical-though-all-but-confirmed worldwide ocean of liquid water beneath a global ice sheath 60 kilometers thick.
The upcoming 2022 multiorbital mission to the Jovian satellite (“Jovian” is the adjectival form of “Jupiter”) to upgrade the primary mission to search for life after years of cuts impacting NASA’s planetary research division. will be called Europa Clipper
“The mission launching after 2022 is under very early study. We do know we want to get to the surface and grab a nice, fresh sample and analyze with instruments that are very well suited,” NASA team leader Dr. Curt Niebur told Geektime last September. “Plumes are great, but they are no substitute to getting into the ocean.”
Multiple people have suggested, worked on designs, and built prototypes for heated drills specially manufactured to burrow through the Europan surface and take the plunge into literal alien waters. The clear hope is the discovery of extraterrestrial (extra-aquative?) life swimming around. Stone Aerospace has produced and already tested (with NASA’s help) the VALKYRIE, a high-energy-laser-infused heat drill designed explicitly for exploring Europa.
They have some major support from one of America’s most famous scientists: Neil DeGrasse Tyson.
2. A low-atmosphere drone for Venus
The Venus Exploration Analysis Group (VEXAG) of NASA’s planetary science division is fighting for a little attention. There are a couple of major proposals that could put Earth’s cosmic sister back in the headlines.
Northrop Grumman is designing a new kind of plane designed to fly through the sweltering, poisonous skies of Venus. The idea is simple: the ground is too hot for conventional metallic gears and machinery, so let’s stay in the air. Northrop calls it VAMP — the Venus Atmospheric Maneuverable Platform — and it was part of the 2016 NASA New Frontiers competition to develop new concepts and missions for the space agency.
Ronald Polidan, Northrop Grumman Aerospace Systems VAMP Project Scientist, introduced the project back in May 2015.
Northrop describes it as the first of a “Lifting Entry Atmospheric Flight (LEAF) family of vehicles” and more succinctly as “an aeroshell-less hypersonic entry vehicle that transitions to a semi-buoyant, maneuverable, solar powered air vehicle for flight in Venus’ atmosphere. VAMP AV will be transported to Venus by a carrier/orbiter spacecraft. Once the spacecraft is safely in Venus’ orbit, VAMP AV is deployed while still attached to spacecraft.”
After a 3-6 month journey to Venus, the ship would insert itself into Venusian orbit, separating the LEAF vehicle from a satellite that would remain circling around the planet.
3. Venus In Situ Explorer
Flying the skies is one thing, but getting to the surface is another entirely. The Soviet Union managed to get several landers to the surface in the 1970s and 1980s, which took the only photos from the Venusian surface in existence. The problem with those landers is they did not last more than two hours, literally melting away as their electronics fried and the machines died.
It was first proposed by the Planetary Science Decadal Survey back in 2003 and is now a candidate via the aforementioned NASA New Frontiers program to head to the second rock from the sun in 2024.
Any working probe would have to withstand the suffocating temperatures on the ground through some sort of combo of advanced cooling mechanisms, advanced materials, or both.
“Feasibility is assessed through a launch-to-landing mission design study where the Venus Intrepid Tessera Lander (VITaL), a VISE science payload designed to inform the Decadal Survey results, is repackaged from a rigid aeroshell into the ADEPT decelerator,” explains an abstract description of the concept written by Brandon Smith, Ethiraj Venkatapathy, and Paul Wercinski. ADEPT — Adaptive Deployable Entry and Placement Technology — is meant to reduce risk to the probe.
“It is shown that ADEPT reduces the deceleration load on VITaL by an order of magnitude relative to a rigid aeroshell. The more benign entry environment opens up the VISE mission design environment for increased science return, reduced risk, and reduced cost.”
4. Moons of Saturn: the Enceladus Life Finder (ELF)
Enceladus is Saturn’s sixth largest moon and resembles Europa in many ways. NASA announced in 2015 its probe Cassini uncovered more evidence of a subsurface ocean on the Hoth-like mini moon
It’s an ice world that also contains geysers spewing water vapor into space, which in turn is entering an icy ring around its parent planet. The ELF mission would analyze the vapor searching for evidence that methane present in the plumes was produced by organisms living close to under-water vents.
“For life, you need certain amino acids, types of carbon, an abundance of methane to other hydrocarbons, and if all these are within a certain range, it’s pretty indicative of a biotic system,” Cornell University astrobiologist Jonathan Lunine, who proposed the idea, said back in 2015 during his first presentation.
NASA conducted a test run for this mission way back in 2008 when it flew the Cassini orbiter through a plume to confirm a host of organic compounds were contained within the water. The flyby found potassium and sodium consistent with the contents of Earth’s own salt water oceans.
ELF’s instruments would specifically look for amino acids (parts of proteins), carbon distribution, and ratios of hydrogen (and carbon) isotopes in comparison with methane.
5. EnEx: Enceladus Explorer
The German Aerospace Center has also entered the fray to explore other worlds. The EnEx is a lander-satellite tandem that would reach Saturn using a nuclear electric proportion and ion thrusters. The lander, with an autonomous machine known as an IceMole on board, would land close to one the moon’s vaporous plumes. The IceMole, an upgraded version of a device used to analyze ice samples on Earth’s poles, would melt its way through the ice as far down as 200 meters to look for microorganisms and biosignatures. The nuclear reactor would power the mole by cable.
A bigger drill similar to plans for Europa is also tantalizing. The subsurface ocean is thought to be 24 miles (39 kilometers) under the ice. That’s even thicker than the 10-15 miles NASA hypothesizes for Europa.
“If EnEx is deployed on Enceladus, it will have to find its way from the surface to a water-bearing region in the ice crust of the Saturnian moon completely autonomously,” DLR Project Manager Oliver Funke has said. “Furthermore, it will have to reliably identify obstructions in the body of ice, such as voids or meteorites, and make its way around them. This means that a robust, autonomous navigation process is a key technology for EnEx, the development of which is absolutely necessary for carrying out such a space mission in future.”
6. Moons of Saturn: Titan Mare explorer would look for life in methane lakes
Astrobiologists — yes, it’s a real profession and it’s pretty interesting — would be quick to throw cold methane on your dreams of finding non-water-dependent aliens, but they will also say it’s too early to dismiss the idea outright. Saturn’s main moon Titan recently got a visit by a robotic lander but didn’t show off much as the lander was limited in abilities. This mission would deliberately land on one of the moon’s methane lakes, where it could possibly, maybe, potentially find life teeming.
The Titan Mare Explorer (or TiME because every acronym has to resemble an actual word apparently) is an idea from Proxemy Research first pitched to NASA back in 2009. It lost out to the InSight mission to Mars during NASA’s Discovery Mission final. Congress declined to fund the project when it came up in 2013.
Methane is a known catalyst for life on earth at so-called Cold Seeps deep on the ocean floor, so it is considered a possibility but remote that such ecosystems could be found on a world that is relatively close to our own.
With other conditions in mind and accepting methane can actually sustain life, researchers including astrobiologist Dirk Schulze-Makuch rate Titan as the most hospitable world besides Earth in our solar system according to his Planet Habitability Index.
“There are all kinds of organic compounds that are falling out of the atmosphere into the sea – we’d love to learn more about the chemical reactions that take place,” TiME Principal Investigator Ellen Stofan said in 2012. “They will not be life as we know it, which is not viable in Titan’s seas. But there will be chemistry in the seas that may give us insight into how organic systems progress toward life.”
7. Twin probes to explore Neptune and Uranus
You read that correctly. Setting a preliminary budget of $2 billion each, NASA Planetary Science Division Head Jim Green is leading a study into the feasibility of sending spacecraft to the two remaining worlds in the Solar System yet to be orbited by man-made objects. The study isn’t scheduled to finish until the early 2020s. According to Spaceflight Now‘s Stephen Clark, NASA’s budget can only support one major interplanetary mission at a time (presumably outside of plans for Mars), so only low-level research can be conducted right now until NASA miraculously sees its budget balloon.
“Obviously, it’s not going to be easy to be able, even after we get Europa under our belt, to actually execute on the next large mission, but we need to make progress to understand our science priorities and look at this in a way that will prepare us for the next decade, but also utilize new technologies and capabilities that have come up (since the last decadal survey),” Green said in 2015. These worlds have only been viewed up close once, by the Voyager probes (it snapped pics of Uranus on December 16, 1986; Neptune on August 1, 1989). Getting back there would likely include observation plans for the local collections of moons. Should a mission be successful, it might be worth incorporating concepts from the Triton Hopper, a mission proposed in 2015 that would collect frozen nitrogen samples on the surface of Neptune’s moon Triton to heat and use as fuel to bounce across the surface.
Just get there
What NASA, ESA, ISRO, large corporations, academies, or other space agencies conceive of is ambitious. These missions are all legitimate proposals whose rejection or viability was more challenged by other projects than undermined for being impractical. Human exploration of the Solar System would mean visiting dozens of celestial bodies and planting flags on every moon around the sun. How long will that take? With advances in technology, hopefully sooner than we think.