A new experimental spacecraft design anticipates the second problem with the techniques of the first. Draper Laboratories received funding this week from NIAC, NASA’s innovative concepts fund, for a two-phase space probe—technology that could both survey a planet and send instruments to its surface.

Where might such a probe go first? Its designers, led by Streetman, think it might be a good way to explore the only orb in the solar system believed to have liquid water: Jupiter’s moon, Europa.

Draper Labs

In its first stage, a small satellite about as large as a half-gallon of milk would orbit the moon. Using two highly accurate accelerometers, it could sense small changes in Europa’s gravitational field, eventually mapping the gravity of the entire surface. These detailed gravity maps could then suggest the location of watery oceans below the planet’s surface—or the openings to these oceans.

Once an ocean (or the entryway to one) was found, the probe would begin its second stage. The small satellite would release even smaller instruments over the interesting region. These “chipsats,” each no larger than a fingernail, could enter Europa’s thin atmosphere unharmed and float down to the surface.

Draper Labs

“When there is an atmosphere, they flutter down like little pieces of paper, not like a rock,” said John West, leader of the advanced concepts team at Draper. He added that while they expect to lose some of the smaller “chipsats,” enough would be released that useful science could be performed.

Once deployed, the tiny chipsats would then send their measurements back to their orbiting mothership, which would in turn beam them back to Earth.

Both of the mission’s vehicles were pioneered in near-Earth orbit. The gravity-mapping satellite draws on cubesat technology, a set of tools and common plans that let satellites be cheaply produced. Last November, a team of high schoolers put a cubesat in orbit. The even smaller “chipsats” were first deployed as part of the space shuttle Endeavour’s final mission in 2011, in partnership with researchers at Cornell University. Cornell is also consulting on the project.

Europa was last studied at close proximity by NASA’s Galileo spacecraft. Over a decade ago, Galileo orbited Jupiter before the probe's human overlords sent it careening into the gas giant’s atmosphere, in part to keep from contaminating Europa’s surface.

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