Mis­cal­cu­la­tion De­stroys Lan­der

In 2016, er­ro­neous height mea­sure­ment makes the Schi­a­par­elli lan­der col­lide with Mars at a speed of 540 km/h.

Science Illustrated - - SPACE/ SOLAR SYSTEM -

When the Eur­poean Space Agency, ESA, launches the Trace Gas probe towards Mars on 14 March 2016, the aims are high. The probe brings the Schi­a­par­elli land­ing mod­ule, and to­gether, the two make up the first part of the Ex­oMars mis­sion, which is to find out whether there is life on the Red Planet.

Ev­ery­thing goes ac­cord­ing to plan, when, three days be­fore its ar­rival to Mars, the probe lets go of its lan­der. Whereas the probe is to or­bit Mars, search­ing for molec­u­lar ev­i­dence of life in the at­mos­phere, Schi­a­par­elli is a test craft, which is to test the land­ing tech­nolo­gies that will be nec­es­sary in 2020, when Ex­oMars is to land a so­phis­ti­cated rover on Mars.

On 19 Oc­to­ber, fol­low­ing three days in a state of hi­ber­na­tion, Schi­a­par­elli is re­ac­ti­vated, start­ing to slow down at an al­ti­tude of 122.5 km. At an al­ti­tude of 11 km, the speed has been re­duced from 21,000 to 1,650 km/h, and the para­chute is ac­ti­vated. When it is shed at an al­ti­tude of 1.3 km, the craft’s mo­tors are to re­duce the speed to 7 km/h. But a neg­a­tive al­ti­tude mea­sure­ment makes the craft shed it para­chute too early, crash­ing onto the red sur­face of Mars.

Rover stuck in Mar­tian soil

With a ra­di­a­tion-scorched, bar­ren sur­face and an at­mos­phere that is al­most only made up of car­bon diox­ide, Mars is not a friendly place. As com­pared to Venus, the Red Planet – with its lower tem­per­a­tures and tol­er­a­ble pres­sure – is nev­er­the­less a world that as­tronomers con­sider an ob­vi­ous place to col­o­nize in the fu­ture.

In an ef­fort to re­search the con­di­tions on the sur­face, NASA and other or­ga­ni­za­tions have over the years sent lan­ders, probes, and rovers to the planet. Of those, 14 have ended their lives on the Red Planet. That is true for the six-wheeled Spirit rover, which has been stuck since 2009.

The rover ar­rived af­ter a six month jour­ney to Mars in Jan­uary 2004 – three weeks be­fore its twin, Op­por­tu­nity. Ac­cord­ing to plan, the rover was to move about for 92 days to col­lect ge­o­log­i­cal and chem­i­cal data, but the mis­sion was pro­longed over and over again. The small rover man­aged to work on the planet 24 times longer than planned and cover at to­tal of 7.73 km – i.e. 12 times longer than the 600 m, which were orig­i­nally the aim.

On 1 May 2009, the rover got stuck in a sandy area of the Gu­sev Crater near Mars’ equa­tor. It con­tin­ued to send data back un­til March 2010, when it failed, prob­a­bly be­cause it had spent the win­ter in a too cold place. For nine months, en­gi­neers of NASA’s Jet Propul­sion Lab­o­ra­tory tried to wake the rover up, but in vain, so the Spirit mis­sion of­fi­cially ended on 11 May 2011.

Since then, NASA en­gi­neers have been work­ing hard to in­vent new wheels, which are not only suited for both soft and hard sur­faces, but can also han­dle more weight. The wheels will prob­a­bly be in­tro­duced on NASA’s 2020 rover.

Miss­ing probe reemerges

Although as­tronomers gen­er­ally know where their space­craft are, a few have gone miss­ing. That is true for the two Soviet Pho­bos 1 and 2 probes, which dis­ap­peared as a re­sult of a com­puter error and an in­cor­rect command from the con­trol cen­tre.

Some­times, en­gi­neers find space­craft again af­ter years without con­tact. In Au­gust 2009, the In­dian space agency lost con­tact with the small Chan­drayaan-1 moon craft. As­tronomers thought that the craft might have been drawn close to the Moon by its grav­ity and had crashed onto the sur­face.

In 2016, NASA in­vents a new method for find­ing even small craft such as Chan­dray-aan-1 or­bit­ing around the Moon. So far, it has been dif­fi­cult, as the light from the Moon can eas­ily pre­vent tele­scopes from spot­ting the small ob­jects. But with the help of two ra­dio tele­scopes lo­cated in Cal­i­for­nia and West Vir­ginia, USA,

NASA was able to spot the small In­dian craft. One tele­scope emit­ted a pow­er­ful mi­crowave sig­nal, af­ter which the other tele­scope re­ceived the re­flected sig­nal from Chan­drayaan-1, as it passed over the Moon’s north pole at an al­ti­tude of about 160 km. The tele­scopes fol­lowed up with ob­ser­va­tions for the next three months, map­ping out the probe’s ac­cu­rate or­bit. Even though the craft has now been found, there is no con­tact.

So far, en­gi­neers must con­se­quently be happy that the probe is not in­cluded in the vast quan­ti­ties of wreck­age on Earth’s loyal fol­lower. A to­tal of 59 crafts, in­clud­ing manned Apollo mis­sions car­ried out by NASA and a se­ries of un­manned craft launched by the space agen­cies of the world have over time left a mix­ture of old land­ing stages, worn-out up­per rocket stages, and other hard­ware on the sur­face of the Moon.

Burn­ing pro­tects worlds with life

On the two gas gi­ants of the So­lar Sys­tem, Jupiter and Saturn, buri­als do not take place as a re­sult of com­puter or en­gine er­rors, they are car­ried out on pur­pose. The plan­ets are huge balls of gas without solid sur­faces to land on, but the rea­son for the sched­uled sui­cides is to be found in a dif­fer­ent place, i.e. on the moons or­bit­ing the gas gi­ants.

Moons such as Jupiter’s Europa and Saturn’s Ence­ladus are at the top of as­tronomers’ list of other So­lar Sys­tem worlds that could in­clude bi­o­log­i­cal life. Even though the sur­faces of the moons are bar­ren and icy, large oceans with liq­uid wa­ter could ex­ist un­der the thick ice sheets. The tremen­dous grav­i­ta­tional pull of Jupiter and Saturn leaves enough en­ergy in the moons to cre­ate a tidal ef­fect that heats the wa­ter, mak­ing it liq­uid. If there is also vol­canic ac­tiv­ity on the ocean floor, as­tro­bi­ol­o­gists sud­denly have all the el­e­ments of the equa­tion that – at least on Earth – are syn­ony­mous with life.

If as­tronomers do one day find life on one of the Moons, they want to make sure that the or­gan­isms are not re­ally from Earth.

Con­se­quently, the space­craft are la­bo­ri­ously as­sem­bled in clean rooms, in which the quan­tity of dust, bac­te­ria, and other sources of con­tam­i­na­tion are min­i­mal. Still, it can­not be com­pletely ruled out that a space­craft could bring mi­crobes from Earth. As sci­en­tists lose con­trol of space­craft, when they run out of fuel, they do not wish to risk that a stray craft strikes one of the moons, leav­ing life from Earth.

When the Juno probe en­ters Jupiter’s at­mos­phere in July 2018 af­ter seven years in space, burn­ing up in the course of a few min­utes, the burial is com­pletely in­ten­tional. Such cre­ma­tion will not only bring the probe close to Jupiter’s at­mos­phere, it will also pre­vent the probe from strik­ing one of Jupiter’s five moons at some point in the fu­ture, leav­ing mi­crobes from Earth.

Only in this way, NASA can make sure that any fu­ture dis­cov­ery of life on another world is surely a sen­sa­tion.

Whereas Juno will be sac­ri­ficed, sci­en­tists have other plans with another guest of the outer So­lar Sys­tem, New Hori­zons. Af­ter a suc­cess­ful mis­sion near Pluto, the probe is now on its way towards the next des­ti­na­tion in the Kuiper Belt, be­fore it will fi­nally end its life in in­ter­stel­lar space.

It can't be ruled out that a space­craft could bring mi­crobes from Earth.

ESA & NASA

The first part of the Ex­oMars mis­sion con­sisted of a probe and a land­ing mod­ule.

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