Researchers want to send SHAMU into space to search for alien life. SHAMU in this case is not an orca, but a Submersible Holographic Astrobiology Microscope with Ultraresolution. Caltech and the NASA Jet Propulsion Lab are leading the development of the device, with collaboration from the University of Washington on microbiology and oceanography aspects of the project. Max Showalter, a UW graduate student in oceanography and astrobiology, gave an interesting talk about SHAMU Monday at Town Hall Seattle. The talk was titled, “Finding Life When the Trail Goes Cold.”
The target for the hunt for alien life is Jupiter’s moon Europa, which has a global ocean.
“That’s really significant when we’re looking for life in our solar system and outer space in general, because everywhere that we’ve found water on Earth we’ve found life, usually in the microbial form,” Showalter explained. The big challenge is that Europa is, on average, about 390 million miles away.
“Since it’s so far from the Sun, it’s really cold on Europa, and it has this crust of frozen ocean on top of it, kind of like our own Arctic Ocean, for example, except it’s eight kilometers thick,” Showalter said. “The question is, when we get to Europa, how do we get through that ice, or can we find a sample of life in that ice?”
You may think that ice is inhospitable, but Showalter said that a lot of things live in arctic ice. Algae have been found in deep cores of ice; enough sunlight can get through to drive photosynthesis. Algae and bacteria can live in brine veins, pockets of salt water within the ice.
This is where SHAMU comes in. The microscope creates a hologram to look for bacteria swimming in an icy water sample. It uses a laser beam split into two parts. One part serves as the control or reference part, the other is able to track changes within the sample.
“You bring those together in the computer and you reconstruct the image and get this 3-D image of what’s going on in this microscope,” Showalter said. “You can think of it as this tiny little cube of liquid that we can now see bacteria swimming around in.”
Showalter pointed out that we can be fooled by fossils, so being able to track something in motion is a key to detecting life.
“That’s an unambiguous biosignature,” he said, but added that multiple converging lines of evidence are needed in order to declare the detection of life. It’s good to see motion, but chemical experiments revealing organics would really be helpful, too.
They’ve tested SHAMU in the lab and found that they could track bacteria swimming around in water as cold as eight degrees fahrenheit; colder than that and the activity pretty much shuts down. Last spring Showalter was part of a team that did a field test of SHAMU in Nuuk, Greenland and they were successful there, too. Ultimately they’d like to take the microscope off planet, and Showalter said Europa would be a great target.
“What’s expecially unique about Europa is that in addition to this icy crust it has geysers on the surface, and these geysers are coming from local hot spots inside the ocean and thinner spots in this icy crust,” he said. This is a big advantage for designing a mission.
“Now we don’t have to worry about drilling through the ice; water is coming to us,” Showalter said. “If we can fly through that and take a sample of that plume, that’s ocean water right there in our hands.”
Europa is not the only place where SHAMU could come in handy. Enceladus, a moon of Saturn, is similar to Europa in that it, too, has an ice-crusted ocean with water geysers. Mars has been found to have some liquid water.
“There are lots of opportunities for us to use this microscope in outer space in addition to places on Earth,” Showalter said. “Hopefully the smallest organisms alive will help us be able to find the answer to one of the biggest questions of humankind: are we alone in the solar system?”