Sidekicks will tell NASA how Mars land­ing goes

The State (Sunday) - - News - BY MAR­CIA DUNN

A pair of tiny ex­per­i­men­tal satel­lites trail­ing NASA’S Insight space­craft all the way to Mars face their big­gest test yet.

Their mis­sion: Broad­cast im­me­di­ate news, good or bad, of Insight’s plunge through the Mar­tian at­mos­phere on Mon­day.

Named WALL-E and EVE af­ter the main char­ac­ters in the 2008 an­i­mated movie, the twin Cubesats will pass within a few thou­sand miles of Mars as the lan­der at­tempts its dicey touch­down.

If these pip­squeaks man­age to re­lay Insight’s ra­dio sig­nals to ground con­trollers nearly 100 mil­lion miles away, we’ll know within min­utes whether the space­craft landed safely.

A look at Insight’s it­ty­bitty sidekicks: Hitch­hik­ers: WALL-E and EVE, each the size of a brief­case, hitched a ride on the same rocket that launched Insight to Mars in May. Cubesats al­ways share rock­ets; they’re too small and in­ex­pen­sive to war­rant their own launch. This Mars Cube One pro­ject, or MARCO, built and man­aged by NASA’S Jet Propul­sion Lab­o­ra­tory, cost $18.5 mil­lion.

Flight for­ma­tion: NASA kept the Cubesats about 6,000 miles away from Insight dur­ing the 300 mil­lion-mile jour­ney to Mars to pre­vent any col­li­sions or close calls. The mini satel­lites were just as far from each other for the same rea­son. The el­bow room in this “very loose for­ma­tion,” as chief en­gi­neer Andy Klesh de­scribes it, has var­ied dur­ing the mis­sion and is nar­row­ing as the space­craft draws ever closer to Mars.

Best be­hav­ior: For the record, EVE has be­haved bet­ter than WALL-E dur­ing the 6 1⁄2-month voy­age to Mars. Each Cube­sat has the same type of cold gas propul­sion that’s used in fire ex­tin­guish­ers to spray foam. In the film, WALL-E uses a fire ex­tin­guisher to pro­pel through space. In re­al­ity, WALL-E has been leak­ing fuel al­most since liftoff. Flight con­trollers have worked around the prob­lem. Mean­while, “EVE seems to fol­low her name­sake and has been fly­ing beau­ti­fully through­out the mis­sion,” said Klesh.

Dry run: In June, WALL-E and EVE aced a se­ries of ra­dio-re­lay tests us­ing sig­nals from a big dish an­tenna near Palo Alto, Cal­i­for­nia. Klesh said that gives en­gi­neers con­fi­dence in the Cubesats’ abil­ity to do the same with Insight’s sig­nals on land­ing day. Last month, the pair sent back pho­tos of Mars from 8 mil­lion miles out. Mars was merely a bright pin­point, but the team said it marked a proud Cube­sat first.

All ears: It takes eight min­utes and seven sec­onds for a ra­dio sig­nal to get from Mars to Earth, one way. It should take less than a minute on top of that to get word from Insight, if the mini satel­lites co­op­er­ate. That means NASA could know Insight’s fate close to real time. If WALL-E and EVE are mum, con­fir­ma­tion would come di­rectly from the lan­der or, hours later, from space­craft cir­cling Mars.

Fu­ture goal: As NASA ex­plores new worlds, it would be handy to have lis­ten­ing out­posts to beam back de­scent and land­ing up­dates. Space­craft al­ready in or­bit around Mars serve that pur­pose when­ever NASA sends a lan­der. But where there are no satel­lites – think as­ter­oids or dwarf plan­ets on the fringes of our so­lar sys­tem – Cubesats could step in, with lit­tle over­head and low cost.

Be­yond Mars: Whether or not they pro­vide any insight on Insight, WALL-E and EVE will zoom past Mars and re­main in an el­lip­ti­cal or­bit around the sun. En­gi­neers ex­pect them to keep work­ing for a cou­ple weeks be­yond Mars de­pend­ing on how long the fuel and elec­tron­ics last.


This il­lus­tra­tion shows the twin Cube­sat space­craft fly­ing over Mars, with Earth and the sun in the dis­tance.

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