"My first wish would be for Mars to blow up so we can look at the rest of the solar system."
Joseph O'Rourke
Assistant Professor ASU School of
Earth and Space Exploration
Dipak Srinivasan, Engineer and Civil Space External Engagements Lead at Johns Hopkins University Applied Physics Laboratory, opens the discussion with a simple statement:
"If there's water, there's life."
On that basis, the solar systems has multiple locations that offer the possibility of life. Europa, the fourth largest moon of Jupiter, is an ice world, and Titan, Saturn's largest moon, has ten times as much water as Earth. Srinivasan is currently involved in missions aimed at exploring both of these satellites: the Europa Clipper mission, and the Dragonfly mission to Titan.
Srinivasan explains that Clipper, scheduled for launch in 2024, will not be looking for life as such, but rather looking for conditions that would support life: water, the right chemical conditions, some form of energy, such as heat, and time - "life needs time to happen". He considers that the discovery of life on Europa would be "transformative".
He points out that there is a period of time when earth "had no biology, just chemistry" and suggests that Titan may be on the verge of same transition that Earth underwent billions of years in the past. Methane is to Titan as water is to Earth, with both clouds and lakes of methane, and Srinivasan sees the flying rotor-driven Dragonfly probe as the best option for exploring in Titan's combination of low gravity and dense atmosphere.
Interestingly, Maitrayee Bose, Arizona State University Assistant Professor at the School of Earth and Space Exploration, and Brett Denevi*, John Hopkins Planetary Geologist are looking for the same thing in two very different places: the history of our solar system.
Bose
is studying small bodies like asteroids and comets, ranging in size
from 10 meters to 500 kilometer - as she says, "The best things come in
small packages." (Although I'm not convinced that a 500 kilometer piece
of space rock counts as a small package.)
These small bodies tell us much about the history of our solar system, how planets form and why they look the way they do. They were the first objects that formed and then accreted to form the larger bodies that became planets.These ancient rocks retain a record of the conditions in the early solar system, and the processes and collisions that took place.
Bose
comments, "They're so diverse, and each one is telling us a story of its
own, a key piece in the evolution of our solar system. They also help
to answer the question of why Earth is so special, why does it have so
much surface water compared to the other planets, how earth got its
water, why it retained it, what different kinds of small bodies may have
provided that water?"
Denevi is conducting her search for
the history of the solar system on the Moon. There are multiple lunar
missions coming up in the near future, the first ones since 1972, with
seven robotic landers currently planned between now and 2024, two of
which will launch later this year.
These robotic probes will be investigating some of the questions that have been on hold over the last 50 years, and learning more about how the Earth and Moon were shaped by impact events early in their history. Denevi explains that the Moon is a better candidate for this process for a very simple reason: "On Earth, we live on this beautiful geologically active world but the problem with that - at least it's a problem for weird planetary geologists like me - is that the Earth's surface is constantly being refreshed by plate tectonics and weathering, so we can't look back into its very earliest history, and on the Moon we don't have those annoying issues."
In Denevi's opinion, the Moon offers crucial information
regarding what was happening in the solar system approximately 4 billion
years in the past, the point at which life began to emerge on Earth.
The Moon shows evidence of massive impact events taking place, such as
the one that created the Mare Imbrium crater, one of the largest impact
craters in the solar system. Similar events on Earth's surface would
have been catastrophic, vapourizing oceans and sterilizing the surface
down to a hundred meters. Precise information from the Moon's craters
will help to understand how those impacts would have affected the Earth.
Joe O'Rourke, Assistant Professor at the ASU School of Earth and Space Exploration, serves on the Steering Committee for NASA’s Venus EXploration and Analysis Group. He's both surprised and disappointed that Venus has been somewhat ignored in terms of missions - in his opinion, it's odd that Titan and Europa are receiving more attention. (He's not wrong, there have been multiple Russian landings on Venus, compared to a single multiprobe mission by NASA almost 45 years ago in 1978.) O'Rourke considers Venus to offer the same opportunities for exploration and research as Mars, including the possibility of surface water in its distant past.
Future Venus missions under consideration are VERITAS, proposed for a 2026 launch date, that would undertake high definition global radar mapping of the Venusian surface, and DAVINCI, an atmospheric probe that would make a surface landing as well.**
The
group had a full wish list for future missions: Io, Triton, Ceres, the
Saturn Trojan points, the planned Viper lunar missions, and, of course,
Joe O'Rourke's fervent desire that Mars would just blow up and get out
of the way.
- Sid
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