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Probe would swim into alien seas

Feb. 9, 2008
Courtesy NASA
and World Science staff

Sci­en­tists hope to send a ro­botic sub­ma­rine in­to oceans that may lurk with­in a moon of Ju­pi­ter, in what could be the first ex­plora­t­ion through li­quid wa­ters on an­oth­er world.

Re­search­ers have long spec­u­lat­ed that un­der the icy shell that en­cases the moon, Eu­ro­pa, liq­uid wa­ter might har­bor prim­i­tive life forms.

Eu­ro­pa as seen by NA­SA's Voy­ag­er 2 space­craft. (Cour­te­sy Voy­ag­er Proj­ect, JPL, NA­SA; ® C.J. Ham­il­ton)

A Eu­ro­pa mis­sion is still years away, ac­cord­ing to sci­en­tists; but in prepara­t­ion for such an ev­ent, they plan to test a NASA-funded ro­botic probe un­der ice on Earth.

Test­ing will take place next week in Lake Men­do­ta on the cam­pus of the Un­ivers­ity of Wis­con­sin, Mad­i­son, ac­cord­ing to a Feb. 8 an­nounce­ment from the agen­cy. 

The sub is made to “swim un­teth­ered un­der ice, cre­at­ing three-di­men­sion­al maps of un­derwa­ter en­vi­ron­ments,” the an­nounce­ment said. The ro­bot would al­so “col­lect da­ta on con­di­tions in those en­vi­ron­ments and take sam­ples of mi­cro­bi­al life.” The pro­ject is led by Uni­ver­sity of Illi­nois at Chi­ca­go and NA­SA scientists.

Af­ter the Wis­con­sin tests, re­search­ers said they plan to ship the probe to a per­ma­nently fro­zen lake in Ant­arc­ti­ca for fur­ther tri­als. The ve­hi­cle, called EN­DUR­ANCE (En­vi­ron­men­tally Non-Disturbing Un­der-ice Robotic Ant­arc­tic Ex­plor­er), is a $2.3 mil­lion proj­ect. It’s a fol­low-up to the Deep Phre­at­ic Ther­mal Ex­plor­er, an­oth­er NASA-funded proj­ect that fin­ished un­derwa­ter tests in Mex­i­co in 2007, agen­cy sci­en­tists said.

Part of Eu­ropa's icy crust, from an im­age made from da­ta gath­ered by NA­SA's Gal­i­le­o space­craft in 1996-97. Many sci­en­tists be­lieve the crust cracked and huge blocks of ice ro­tated slight­ly be­fore be­ing re­fro­zen in new po­si­tions. The blocks' size and shape sug­gest an un­der­ly­ing lay­er of icy slush or liq­uid wa­ter moved them, re­search­ers say.

Eu­ro­pa, slightly smaller than Earth’s Moon, is the fourth larg­est of Ju­pi­ter’s at least 16 moons, and is cov­ered with whit­ish and brown ice. Be­neath it, many re­search­ers be­lieve the moon may har­bor the only glob­al ocean of liq­uid wa­ter in our So­lar Sys­tem be­sides Earth’s.

Im­ages from NASA’s Gal­i­le­o space­craft have shown ar­eas with si­m­i­lar­i­ties to Earth’s ice-floe cov­ered Arc­tic oceans, sug­gest­ing the ex­ist­ence of wa­ter or warm “s­lushy” ice be­low, ac­cord­ing to Da­vid R. Wil­liams, a sci­ent­ist at the agen­cy’s God­dard Space Flight Cen­ter. Such an ocean could con­ceivably pro­vide a home for liv­ing things.

Eu­ro­pa’s in­te­ri­or is hot­ter than its sur­face, ac­cord­ing to Wil­liam B. McK­in­non, a plan­e­tary sci­ent­ist at Wash­ing­ton Un­ivers­ity in St. Lou­is. This in­ter­nal heat comes from the gravita­t­ional pull of Ju­pi­ter and its oth­er large moons, which stretch Eu­ro­pa’s in­sides in dif­fer­ent di­rec­tions and cre­ate fric­tion. Most of the sat­el­lite is made of rock, ac­cord­ing to McK­in­non.

Re­peat­ed split­ting and shift­ing of the sur­face ice, and dis­rup­tions from be­low, have re­shaped Eu­ro­pa’s sur­face, Mcin­non con­tin­ued. A re­sult is that there are few vis­i­ble im­pact craters, since the shift­ing would have erased these. The sur­face shows shal­low cracks, val­leys, ridges, pits, blis­ters, and icy flows, McK­in­non added, none more than a few hun­dred yards or me­ters high or deep. 

The Ital­ian as­tron­o­mer Gal­i­le­o discov­ered Eu­ro­pa 1610. Its name is said to have been first sug­gested by his con­tem­po­rary, the Ger­man as­tron­o­mer Kep­ler, who pro­posed nam­ing Ju­pi­ter’s moons af­ter the se­cret mis­tresses of Ju­pi­ter, king of the gods in Greek and Ro­man my­thol­o­gy. Ac­cord­ing to myth, Ju­pi­ter took the form of a bull to ab­duct Eu­ro­pa, a Phoe­ni­cian prin­cess.

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Scientists hope to send a robotic submarine into oceans that may lurk under the surface of a moon of Jupiter, in what could be the first exploration of waters on another world. Researchers have long speculated that under the icy shell that encases the moon, Europa, liquid water might harbor primitive life forms. A Europa mission is still years away, according to scientists; but in preparation for such a mission, they plan to test a NASA-funded robotic probe under ice on Earth. Testing will take place next week in Lake Mendota on the campus of the University of Wisconsin, Madison, according to a Feb. 8 announcement from the agency. The sub is “designed to swim untethered under ice, creating three-dimensional maps of underwater environments,” the announcement said. The robot would also “collect data on conditions in those environments and take samples of microbial life.” After the Wisconsin tests, researchers said they plan to ship the probe to a permanently frozen lake in Antarctica for further trials. The vehicle, called the Environmentally Non-Disturbing Under-ice Robotic Antarctic Explorer, is a $2.3 million project. It’s a follow-up to the Deep Phreatic Thermal Explorer, another NASA-funded project that finished underwater tests in Mexico in 2007, agency scientists said. Europa, slightly smaller than Earth’s Moon, is one of the largest Jupiter’s dozens of moons, and is covered with white and brown ice. Beneath it, many researchers believe the moon may harbor the only global ocean of liquid water in our Solar System besides Earth’s. Images from NASA’s Galileo spacecraft have shown areas with similarities to Earth’s ice-floe covered Arctic oceans, suggesting the existence of water or warm “slushy” ice below, according to David R. Williams, a scientist at the agency’s Goddard Space Flight Center. Such an ocean could conceivably provide a home for living things. Europa’s interior is hotter than its surface, according to William B. McKinnon, a planetary scientist at Washington University in St. Louis. This internal heat comes from the gravitational forces of Jupiter its other large moons, which stretch Europa’s interior in different directions and create friction. Most of the satellite is made of rock, according to McKinnon. Repeated splitting and shifting of the surface ice, and disruptions from below, have reshaped Europa’s surface, Mcinnon continued. A result is that there are few visible impact craters, since the shifting would have erased these. The surface shows shallow cracks, valleys, ridges, pits, blisters, and icy flows, McKinnon added, none more than a few hundred yards or meters high or deep. The Italian astronomer Galileo discovered Europa 1610. Its name is said to have been first suggested by the contemporary German astronomer Johannes Kepler, who proposed naming Jupiter’s moons after the clandestine mistresses of Jupiter, king of the gods in Greek and Roman mythology. According to myth, Jupiter took the form of a bull to abduct Europa, a Phoenician princess.