What do scientists want to explore next in the solar system?

 

T'is the summer of the National Academies Planetary Decadal Survey a chance for the community to come together and motivate the next ten years of space missions. Because Planetary depends heavily on this kind of "Big Science" it makes sense to organize. The last time, Mars Sample Return was the winner and since MSR looks to feature prominently in the coming decade it will be interesting to see how everything plays out. For now, the Science White Papers are in! But the Mission White Papers and the Community White Papers have yet to come - those will be in August and September, respectively.

By Hemani Kalucha

July 15 marked the submission of Science White Paper proposals to the Planetary Science Decadal Survey. Every 10 years, the scientific community makes a plan of what they want to explore next in the universe; this is called the decadal survey. It is written by roughly a 100 scientists, all with different expertise across a range of fields. Based on the science they want to accomplish, they develop mission proposals and budgets that strongly influence space agency activity for that decade. The next decadal survey will be published in 2023, and as a part of this process, the survey committee asks for the input of scientists around the world, which is published in the form of whitepapers. The whitepapers are open to everyone and can be read here: https://www.nationalacademies.org/our-work/planetary-science-and-astrobiology-decadal-survey-2023-2032. I, myself, got the chance to be a co-author on my first whitepaper this time (pictured above), which made me feel a little less like a new grad student and more like a real scientist!

Out of the 341 papers submitted, roughly 48 were about Mercury/The moon, 37 were about Venus, 74 were about Mars, 41 were about giant planets (Jupiter, Saturn, Uranus, Neptune), and 50 were about ocean worlds (Titan, Enceladus, Europa). The whitepapers explored themes like prebiotic organics, habitability, solar system formation, geological evolution, atmospheric evolution, and more. As I was going through the list, a few titles really stuck out to me, and so I’ve shared them below with a little description of the scientific gap they are trying to address. There are, of course, whitepapers on expected topics such as Mars Sample Return, Mars subsurface research, the return to the Moon, and the radiation belts of Jupiter. The reasons for these missions have been justified several times, so I won’t go into them here.  

Dive, Dive, Dive: Accessing the Subsurface of Ocean Worlds: This paper and a host of other papers recommend a development program of ocean-world exploration surface technology this decade, in order to achieve a subsurface mission to first Enceladus and then Europa in the 2033-2042 decade. The technology required includes drills that can reach 15-20 km into Europa’s ice sheet, sample handling systems that can manage liquid samples, reliable through-ice communication systems (tethered and wireless), guidance and navigation systems capable of identifying in-ice hazards, and compact power systems for deep ice probes. Although this sounds like a daunting set of requirements, a lot of technology that is used in deep ocean exploration on Earth can give heritage to these types of missions, which is an exciting crossover! 

Venus, an astrobiology target: This paper suggests that there could be life living in the acidic clouds of Venus! Venus is thought to have sustained oceans in its past for a long period of time – 600 million years, which allows for a source of water activity in the clouds. In addition, clouds on Venus have earthlike temperatures and pressures, suggesting the possibility of airborne microbial species. Even though the clouds are highly acidic, the paper claims that bacteria like the acidophiles found on Earth may be able to survive. One of many obstacles is the fact that though airborne bacteria have been detected on earth, airborne reproduction is yet to be found, which means if bacteria do exist in the clouds of Venus, they might still need to land on the surface occasionally. However, the surface is extremely hostile to bacteria…needless to say, I appreciated the creativity of this paper, even though it may be hard to find life on Venus.  

Science and technology requirements to explore caves in our solar system: the idea of accessing the martian subsurface using caves has been discussed for some time now. It turns out that caves exist on a host of other bodies in the solar system: Titan, Ceres, Venus, Europa, Enceladus, Ganymede, Io, and even Vesta the asteroid! Caves are extremely useful features: they provide access to the geological record without the need for drilling, and preserve volatiles, ice, and organic matter, all while sheltering the material from radiation! This paper therefore suggests that a large effort of exploration go towards cave exploration. This would begin with identifying caves all over the solar system using flybys and orbiters, and then exploring caves of high interest with drones, crawlers, and microbots. One day, it may even be possible to set up sensor networks inside the caves for continuous monitoring.