EX­PLOR­ING SPACE: WHERE TO NEXT

One epic pe­riod of space ex­plo­ration has come to an end. RICHARD A. LOVETT looks for­ward to the next.

Cosmos - - Front Page - RICHARD A. LOVETT is a sci­ence writer and sci­ence fic­tion au­thor based in Port­land, Oregon. IMAGES 01 NASA 02 Dim­itri Geron­di­dakis / NASA

THE PAST FEW YEARS have been a hal­cyon era for space ex­plo­ration. In the span of lit­tle more than a decade, NASA’S New Hori­zons space­craft whizzed by Pluto and the gi­ant moon Charon, its Cu­rios­ity Mars rover rolled across a Mar­tian crater look­ing for traces of once-hab­it­able en­vi­ron­ments, and the Euro­pean Space Agency’s Rosetta space­craft ren­dezvoused with a comet. The Euro-amer­i­can Cassini space­craft or­bited Saturn, drop­ping the Huy­gens lan­der on the gi­ant moon Ti­tan and pro­vid­ing close-up views of many of the ringed planet’s other moons. Other space­craft or­bited Mer­cury and the Moon, vis­ited the So­lar Sys­tem’s two largest as­ter­oids, skimmed Jupiter’s cloud­tops, and re­turned dust sam­ples from an as­ter­oid and the tail of a comet.

Many of these mis­sions have ei­ther ended or are about to. Even the work­horse Cassini mis­sion, or­bit­ing Saturn since 2004, fi­nally ran out of ma­noeu­ver­ing fuel, tak­ing a ter­mi­nal swan dive into Saturn’s up­per at­mos­phere in Septem­ber.

It feels like the end of an era. But that’s just part of the nor­mal ebb and flow of a vi­brant multi-decadal pro­gram, says Steve Squyres, a plan­e­tary sci­en­tist from Cor­nell Univer­sity who heads up the sci­ence team for NASA’S Op­por­tu­nity Mars rover.

Op­por­tu­nity has cov­ered 45 km of Mar­tian ground in the 13 years since its 2004 land­ing, and con­tin­ues to make dis­cov­er­ies. It has out­lived its 90-day de­sign life by a fac­tor of more than 50.

A num­ber of satel­lites con­tinue to ob­serve the Red Planet from or­bit. There are talks of land­ing on one or the other of Mars’ tiny moons, and a plan for a new rover, po­ten­tially to be launched in 2020, bet­ter equipped and even more durable than those that came be­fore. “Things are great at Mars,” Squyres says.

The rea­son it looks like the end of an era, he says, is that all mis­sions have a nat­u­ral life­cy­cle. “In a ro­bust pro­gram, there will be mis­sions at var­i­ous states in their life­cy­cles, rang­ing from ear­li­est for­mu­la­tion to mis­sion end. When a big one like Cassini comes to an end, it can feel like the end of an era, but it’s not. It’s just the end of that one mis­sion.”

Two of the most ex­cit­ing mis­sions on the plan­ning board in­volve Jupiter. One is the Europa Clip­per. This NASA mis­sion would dive in and out of Jupiter’s pun­ish­ing ra­di­a­tion belts to per­form dozens of close flights past the icy moon Europa, which sci­en­tists be­lieve holds a sub-sur­face ocean that might be suit­able for life. Ap­proaches would range from 2,700 km to as close as 25 km. There are even thoughts of a pos­si­ble Europa lan­der, Squyres says. The launch date has not been locked in but is slated for some time in the 2020s.

An­other Jupiter mis­sion is JUICE, which stands for Jupiter ICY moons Ex­plorer. This ESA mis­sion could beat the Europa Clip­per off the launch pad, ar­riv­ing at the gi­ant planet as early as 2030. It would then spend three years ex­am­in­ing three of Jupiter’s four largest moons: Ganymede, Cal­listo and Europa.

Other mis­sions will stay closer to home. Ja­pan’s space agency, JAXA, has a space­craft called Hayabusa 2 al­ready en route to one of the Apollo group of nearearth as­ter­oids, 162173 Ryugu.

In 2010, Hayabusa 2’s pre­de­ces­sor be­came the first mis­sion to bring back sam­ples from the sur­face of an ex­trater­res­trial body other than the Moon when it vis­ited an­other Apollo group as­ter­oid, 25143 Itokawa. Un­for­tu­nately, due to me­chan­i­cal prob­lems with the probe’s sam­pling de­vice, the Ja­panese were only able to col­lect tiny amounts of mi­cro­scopic dust.

This time the plan is to use an ex­plo­sive de­vice to dig a crater in the sur­face of 162173 Ryugu, to ex­pose un­der­ly­ing ma­te­rial and col­lect some­what larger sam­ples, to be brought back to Earth in 2020.

NASA is at­tempt­ing some­thing sim­i­lar with a

“When a big mis­sion like Cassini comes to an end, it can feel like the end of an era, but it’s not. It’s just the end of that one mis­sion.”

space­craft called OSIRIS-REX, al­ready head­ing for an­other Apollo group as­ter­oid, 101955 Bennu. The as­ter­oid is ranked as the third most dan­ger­ous po­ten­tial Earth im­pactor, with eight chances of hit­ting us be­tween 2169 and 2199. At 500 me­tres in di­am­e­ter, it is big enough to pack a se­ri­ous wal­lop; the as­ter­oid that ex­ploded above Chelyabinsk, Rus­sia, in 2013, in­jur­ing nearly 1,500 peo­ple, was only 20 me­tres in di­am­e­ter.

In part, the OSIRIS-REX mis­sion’s goals are sci­en­tific – Bennu ap­pears to be a “prim­i­tive” as­ter­oid pro­ten­tially pro­vid­ing clues to con­di­tions at the dawn of the So­lar Sys­tem. But the pri­mary goal is to find out what the as­ter­oid is made of in case we have to at­tempt to de­flect it some­day. To de­ter­mine that, the mis­sion hopes to re­turn a cou­ple of kilo­grams of ma­te­rial back to Earth. If OSIRIS-REX and Hayabusa 2 both suc­ceed, we will have sur­face sam­ples from three dif­fer­ent as­ter­oids for com­par­a­tive anal­y­sis.

New Hori­zons, mean­while, isn’t dead. Its dra­matic flyby of Pluto and Charon two years ago left it with enough fuel to ad­just course for a 2019 ren­dezvous with an­other outer So­lar Sys­tem body. The new tar­get, the Kuiper belt ob­ject 2014 MU69, is so dis­tant it wasn’t even dis­cov­ered un­til 2014, when astronomers were look­ing for in­ter­est­ing ob­jects be­yond Pluto to­ward which New Hori­zons could be di­rected. Noth­ing that far out in the So­lar Sys­tem has ever be­fore been seen ex­cept as fuzzy dots in te­le­scope images.

Head­ing in the op­po­site di­rec­tion, a joint Euro­pean-ja­panese mis­sion called Bepi­colombo, sched­uled for launch in 2018, is aim­ing to reach Mer­cury in 2025. It com­prises two or­biters that will work in tan­dem from dif­fer­ent po­si­tions. At one point the mis­sion planned to have a lan­der but that, sadly, was can­celled due to bud­get con­straints.

Closer to home, China and In­dia have Moon mis­sions planned for the near fu­ture. China’s Chang’e 5 hopes to re­trieve soil sam­ples and is sched­uled for lift-off in Novem­ber. In­dia’s Chan­drayaan 2 mis­sion to land a lu­nar rover is sched­uled for 2018.

Mean­while, Squyres says, there is fierce com­pe­ti­tion un­der­way for the next NASA “New Fron­tiers” mis­sion, the class that in­cludes New Hori­zons, Juno and OSIRIS-REX. There are 12 pro­pos­als fight­ing for se­lec­tion, he says. The de­tails of these mis­sion pro­pos­als aren’t pub­licly avail­able but, all told, he is con­fi­dent “the fu­ture looks as bright and ex­cit­ing as it ever has”.

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