Scouring Mars for answers to life on Earth

We are see­ing a grow­ing num­ber of mis­sions to Mars. Why is there so much inter­est in the red planet?

Juli­ette Lam­bin. There is a lot of talk about it at the moment because sev­er­al mis­sions to Mars are coin­cid­ing with one anoth­er. This is because the opti­mal launch win­dow occurs once every two years and only lasts a fort­night – so the mis­sions tend to all hap­pen at the same time. 

That said, Mars is a major object of study in “uni­verse sci­ence”. It is par­tic­u­lar­ly inter­est­ing because it is small­er than Earth but was formed at the same time. Also, in the begin­ning, con­di­tions on Mars were quite sim­i­lar to those on our own plan­et. Name­ly, a dense atmos­phere, liq­uid water, a large-scale mag­net­ic field; in oth­er words, the nec­es­sary ingre­di­ents for the emer­gence of a form of life. More than 3.5 bil­lion years ago, how­ev­er, Mars lost all that and became almost frozen in time. As such, it remained in more or less the same state that the Earth was in when life first appeared. 

From a sci­en­tif­ic point of view, what we are look­ing for on Mars are traces of fos­silised life. These are traces that can­not be found on Earth because there is no place as old as that, which has not been trans­formed by ero­sion, plate tec­ton­ics, over­run with mod­ern activ­i­ty, etc. So, look­ing for traces of life on Mars means look­ing for pos­si­ble traces of prim­i­tive life on Earth! Mars is the best and most acces­si­ble object of study for exo­bi­ol­o­gy: the study and under­stand­ing of every­thing that can lead to the appear­ance of life. 

The aim of this pro­gramme is to take sam­ples of the Mar­t­ian soil and bring them back to Earth for analy­sis using ter­res­tri­al means.

How will the Mars Sam­ple Return mis­sion and the arrival of the Per­se­ver­ance rover on Mars con­tribute to these studies?

The rover, Per­se­ver­ance, is the first of sev­er­al mis­sions con­tribut­ing to the Mars Sam­ple Return (MSR) pro­gramme, car­ried out by the Amer­i­cans in asso­ci­a­tion with Europe. The aim of this pro­gramme is to take sam­ples of Mar­t­ian soil and bring it back to Earth for analy­sis that will be com­plet­ed around 2030. Up to now, mis­sions have main­ly been car­ried out in orbit around the plan­et using satel­lites, fol­lowed by robot­ic explo­rations with the rovers that have land­ed. These mis­sions have pro­vid­ed a good descrip­tion of the topog­ra­phy, com­po­si­tion of the atmos­phere and geol­o­gy of the sur­face of Mars. We have already detect­ed ice caps and iden­ti­fied geo­log­i­cal struc­tures that look like runoff, which could be caused by liq­uid water that would have flowed on the sur­face Mars in the past. 

The twin rovers, Spir­it and Oppor­tu­ni­ty, launched in 2003 as part of the Mars Explo­ration Rover mis­sion, as well as the Curios­i­ty rover of the Mars Sci­ence Lab­o­ra­to­ry mis­sion launched at the end of 2011, changed the game because they could move. In addi­tion to cli­mate analy­sis, Curios­i­ty’s main objec­tive was to deter­mine the past hab­it­abil­i­ty of Mars based on the analy­sis of rocks and min­er­als. The Per­se­ver­ance rover is more autonomous than pre­vi­ous rovers and its mis­sion is dif­fer­ent. Not only will it search for pos­si­ble biosig­na­tures, but it will also take sam­ples and place them in sealed tubes from sev­er­al loca­tions. They will then be retrieved and brought back to Earth where they will be analysed.

Why can’t these sam­ples be analysed direct­ly on Mars?

Because of the con­straints of mass, vol­ume and auton­o­my. A Mar­t­ian rover car­ries very sophis­ti­cat­ed instru­ments, but they are minia­turised and there are not many of them – only 7 on Per­se­ver­ance, for exam­ple. The search for life, dat­ing of rocks and fine min­er­al analy­sis all require instru­ments that they can­not be sent to or oper­ate on Mars. Some biol­o­gy or bio­chem­istry exper­i­ments involve so many exper­i­ments and com­pli­cat­ed steps that only they can only be done by sci­en­tists, using sen­si­tive equip­ment only found back on Earth. 

In order to analyse the sam­ples brought back, there must also be a strict seal pro­to­col. Hence, sam­ples will be quar­an­tined in high bio­log­i­cal safe­ty lab­o­ra­to­ries (P4 type) and pro­tect­ed from any bio­log­i­cal or chem­i­cal con­t­a­m­i­na­tion by ter­res­tri­al com­pounds. The first quar­an­tine stud­ies will also seek to detect any pos­si­ble Mar­t­ian life forms or bio­log­i­cal risk agents.

What is the role of CNES in the Mars Sam­ple Return programme?

CNES is respon­si­ble for the entire French con­tri­bu­tion to this pro­gramme in coop­er­a­tion with NASA. We work in close col­lab­o­ra­tion with CNRS sci­en­tists, who devel­op the sci­en­tif­ic instru­ments and study the data from the exper­i­ments, and with indus­tri­al part­ners. In Toulouse, CNES is home to the FOCSE for “French Oper­a­tion Cen­ter for Sci­ence and Explo­ration”. This cen­tre, which already oper­ates the equip­ment of rovers from the pre­vi­ous gen­er­a­tion, in par­tic­u­lar the Chem­Cam (CHEM­istry CAM­era) and SAM (Sam­ple Analy­sis at Mars) cam­eras, ensures the oper­a­tion of the Super­CAM instrument. 

Every day, the Toulouse team analy­ses the data received the day before and, after coor­di­nat­ing with the peo­ple in charge of the pro­gramme at the Jet Propul­sion Lab­o­ra­to­ry (JPL) in Pasade­na, Cal­i­for­nia, sched­ules the exper­i­ments con­duct­ed by the Fran­co-Amer­i­can instru­ments on board Curios­i­ty and Per­se­ver­ance. With trans­mis­sion times between Earth and Mars vary­ing between 4 and 20 min­utes and patchy vis­i­bil­i­ties, the Mar­t­ian rovers are not direct­ly remote-con­trolled. They are con­trolled by send­ing dai­ly pro­grammes which are then auto­mat­i­cal­ly sent out. The pro­grammes are writ­ten by the teams of each instru­ment, then checked and assem­bled at the JPL, which sends them. We work on US West Coast time. Even though we often start at 10PM and fin­ish at 4AM, it’s a fan­tas­tic way to work from Toulouse, France, to pilot a robot on Mars.

Interview by Sophy Caulier