Robert Hurt: Caltech, astronomer
Tiffiny Kataria: Exo-planetarian, NASA jet propulsion laboratory
Morgan Cable: Astrochemist, NASA jet propulsion laboratory
Cynthia Phillips: Planetary Geologist, NASA NASA jet propulsion laboratory
Cynthia: The first candidate for finding life is Europa, Jupiter’s moon. Its surface temperature is 100 degrees Kelvin (-173 Celsius), and it is covered in ice, but below it has more water than all of Earth’s oceans. Liquid water with the right chemical elements for life, and possibly chemical energy source at its bottom from Europa’s core. Alternatively, radiation from Jupiter can provide an energy source. Also, it has time on its side – Europa’s ocean is liquid from the start of the universe, so that gives a lot of time for the formation of life.
There are two missions planned to Europa:
- The Europa Clipper, which will do a fly-by, set to launch in 2022-2025
- The Europa Lander, which will land on the surface and sample the ground. It has a suggested launch date of 2024.
Morgan: Another good candidate is Enceladus, Saturn’s moon. It also has a liquid ocean beneath a crust of ice. It may be geologically active, and plumes of icy particles were spotted over its south pole. These could be sampled with a satellite doing a fly-by. There may be hydro-thermal vents at the bottom of Enceladus, which could support life.
Titan is another moon of Saturn that is considered a candidate for finding life – it has an atmosphere, and there is liquid on its surface. Titan has rivers and lakes of liquid methane. These may support life, although if they do, it will be a very different form of life than the one we know.
Tiffiny: Beyond our solar system we are looking at the stars for planets. We look for changes of light (which tells us if it is a rocky planet, like Earth or a gas giant, like Jupiter), radial velocity, and recently we’ve been taking pictures through direct imaging, where we block out the star’s light to catch the orbiting planet. Until now we’ve discovered over 3000 exoplanets. We found desert planets, planets orbiting two stars, and others. We use spectroscopy to look for signatures of molecules that would indicate life – water, methane, ozone, and other signatures we know. We are mapping for athmosphere. For example the trapper star system with seven Earth-sized planets.
Robert: What I do is try to engage the audience by trying to add imagery behind the exoplanets – giving them color and graphics. Take queues from Hollywood, who are very good at making space engaging to the mass audience. Try to provide images based on as much scientific information as possible while still keeping it interesting. So for example if a planet is known to be covered by water, but also has a thick cloud layer, we would perhaps draw some space between the clouds to show the surface and make the image more compelling to the public, even at the expense of some scientific accuracy.
Cynthia: What about intelligent life? SETI looked for this by looking for radio telescopy signals. Right now we are looking for both intelligent life as well as “stupid” life – single cell life, animal life, any life not building radio telescopes. Scientists will be satisfied with finding even microbes.
Morgan: Another overlap of science fiction and real life is the Star Trek concept of the Prime Directive, which protects from harming other under developed life forms; NASA has a similar guiding principle called “Planetary Protection”, designed to prevent bringing contamination back to Earth from space, and prevent contaminating other planets. That is why the Cassini craft was purposefully crashed on to Saturn, to avoid its accidentally contaminating one of Saturn’s moods.
Robert: We can’t do statistics on a sample size of one, and in regard to life, that’s our sample size. So we really have no possibility to extrapolate as to the chance of life on other planets.
What would it take to find life? Do we have the technology?
Morgan: We do have this, and it is essentially the methods we are taking now.
Tiffany: Voyager took 40 years to get to the edge of the solar system, but it would take 40,000 years to get to the nearest found planet – Proxima. So we will need to focus on observation.
Question: Plate tectonics is important for life on Earth, are we looking for that in other planets?
Tiffany: We don’t really know how to detect that.
Question: How critical is radiation for life?
Morgan: Radiation is harmful to life, but it can create conditions for life by breaking up material.
Question: How do you sanitize the Europa lander?
Morgan: We did learn a lot more about sterilizing since the Cassini days.
Cynthia: To get permission from the planetary protection body you need to show very stringent standards for protecting the landed planets.
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