For every space mission that leaves the launch pad, dozens of proposals die on the cutting room floor. Most fall victim to budgetary constraints, as NASA and planetary science as a whole face dwindling funds for planetary exploration. Exciting missions are currently underway; Messenger is in orbit around Mercury, the Dawn spacecraft is en route to the asteroid Ceres, and New Horizons is scheduled to make a flyby of Pluto in July 2015. However, it’s rather telling that no nation has a planetary mission scheduled to leave Earth in 2012. Still, scientists have a lengthy “wish list” of future missions they’d like to see launched, and some of these involve rather strange concepts.
5. A Blimp to Study Saturn’s Moon Titan
In 2004-05 the European Space Agency’s Cassini spacecraft in orbit around Saturn released a probe, Huygens, which successfully landed on the large moon Titan. Titan is a fascinating place, a moon large enough to have a dense atmosphere, lakes of ethane and liquid methane, and a hydrologic cycle. One current proposal to study Titan involves using a scientific payload suspended from a balloon or blimp. Sounds strange, yes, but using a blimp has some advantages. Such a mission would slowly float over the terrain and survey the world below. A Titan blimp would monitor changes in the atmosphere as well as examine the surface below visually and via radar. With a cruising altitude of about 20 miles above the surface, a Titan blimp could circle the moon once every 16 days. Such a mission would take advantage of the dense atmosphere and be able to examine a large swath of the terrain rather than a single site. An obvious question: How would the blimp be inflated? In one proposal, a nuclear power source’s radioactive decay would be converted into electricity and heat, which could then be used to inflate the blimp. Another proposal would involve using hydrogen in the blimp. This mission, originally proposed to launch in 2020, has been postponed.
4. A Venus Rover
Venus is a tough place to operate. The nearest planet to Earth and just slightly smaller than our world, it’s a parched landscape with daytime temperatures reaching over 800 degrees Fahrenheit. And that’s just for starters; the atmospheric pressure is over 90 times that of the Earth at sea level and it also contains corrosive sulfuric acid. Beginning in the 1960s, Russians successfully landed 10 Venera spacecraft on the Venusian surface that actually returned images for anywhere from 20 minutes to two hours before succumbing to the intense environment. Still, there are proposals to send rovers to Venus similar to those operating on Mars. A large mission would send an orbiter to deposit a fleet of rovers across the Venusian surface. Obviously, the electronics in these rovers would have to be heavily protected and cooled continuously. Like Mars Curiosity, such a rover would also have to be nuclear powered, as sunlight does not reach the planet’s surface. An unusual alternative proposal is a Venus glider, which could stay up in the relatively “cool” layers of the atmosphere and take advantage of solar power, examining the ground below via radar.
3. An Orbiter For Uranus
The first planet discovered telescopically, Uranus has only been visited once, by Voyager 2 in 1986. During that brief flyby, Voyager 2 glimpsed a fascinating system of rings, moons, and dynamic weather activity. A Uranus orbiter would be the first spacecraft to permanently orbit and study Uranus from close up. It would be similar in design to Galileo, the only spacecraft to orbit Jupiter, and Cassini, which is currently orbiting Saturn. It would be a difficult mission; engineers would have to balance a desire to get there quickly (Uranus is 19 times further from the Sun than the Earth) and the fact that it would have to slow down enough to achieve orbit. By comparison, the New Horizons spacecraft launched in 2006 is cruising at over nine miles per second and will only have a brief flyby of Pluto in July 2015. This mission, proposed as a joint effort between NASA and the European Space Agency, would launch in the early 2020s. Hopefully, if ever approved, NASA will have the public relations foresight to avoid calling it a “Uranus probe.”
2. A Submersible Craft For Jupiter’s Moon Europa
Jupiter’s moon Europa is a fascinating place. Enshrouded in ice, there’s ample evidence that a large liquid ocean may exist a few kilometers below. The ice would protect it from hazardous radiation, while it would be heated from below by tidal flexing of its core by nearby Jupiter. This possibility has put Europa on the short list of places were life might exist in the solar system. One proposal would place a lander on the surface complete with a submersible vessel that would melt through the ice to venture into the subsurface seas of Europa. Again, this vessel would most likely use a nuclear power source to melt through to the ocean beneath. But the big question that first must be addressed: How thick is the ice on Europa? A submersible would have its best chances of penetrating the ice near a thin layer, perhaps along several of the large grooves that crisscross the moon’s surface. Life in the seas of Europa would be an amazing find.
1. A Boat For Saturn’s Moon Titan
One of the most intriguing concepts in recent years also targets Saturn’s moon Titan. The idea is to explore the moon by floating a boat on its liquid hydrocarbon seas. Dubbed the Titan Mare Explorer, TiME is envisioned as a low-cost mission that would examine the moon in detail and look for possible evidence of life. Titan is the only place other than the Earth in our solar system that possesses a liquid ocean at its surface, and a “Titan Lake-lander” would be a first of its kind. TiME was one of three mission proposals selected by NASA for further study in 2011, along with a mission known as Comet Hopper and the Mars InSight Lander, which would study the interior of the Red Planet. InSight was selected for further funding in August of 2012, shelving TiME and any possibility of sailing on an extraterrestrial sea until after 2020.