Earth_Magazine_October_2017

7IXYVRMRKEQTPIWERH

IRHMRK-YQERW

Beyond the horizon of the 2020 missions and

the search for biosignatures lie two other lofty

and longstanding Red Planet objectives: returning

rock and soil samples to Earth, and, eventually,

sending humans to explore Mars in person. These

goals have been stated and reiterated by space

agencies, planetary scientists and space enthusiasts

for decades, including in a NASA authorization

bill signed by President Trump in March that

reaffirmed the agency’s goal of sending humans to

Mars in the 2030s.

Past missions, particularly landers, have collected

valuable data related to entry, descent and landing

through the atmosphere, as well as weather and

radiation conditions at the surface, all of which could

broadly inform more ambitious sample return or

manned missions. To date, though, little headway

has been made in directly addressing the particular

challenges of these missions. Some of the 2020

efforts, if successful, may change this.

In addition to continuing studies of weather and

entry, descent and landing conditions, one of the

main tasks for NASA’s 2020 rover will be to not

only drill and analyze rocks, as Curiosity did, but also

to stow, or cache, up to about 30 15-gram samples

in secure containers that could be retrieved and

returned to Earth by a future mission. Although both

NASA’s rover and the ExoMars rover are equipped

with sensitive instrumentation for hunting for signs

of life, remotely determining whether a biosigna-

ture on Mars represents unequivocal evidence of

extraterrestrial life would be extremely difficult, and

likely controversial. “The reality is that the burden

of proof for the detection of life outside of Earth is

enormously high, and it’s unlikely that the instru-

ments we have on board will overcome that burden,”

Farley says. “By bringing samples back to Earth, we

can apply the whole arsenal of instrumentation that

3&&MWIZEPYEXMRKXLVIIGERHMHEXIPERHMRKWMXIWJSVMXWȶȉȶȉVSZIV/I^IVS(VEXIVERH3]VXMW2ENSVMRXLIRSVXLIVRLIQMWTLIVI
ERHXLI(SPYQFME-MPPWMRXLIWSYXLIVRLIQMWTLIVI8LI\S2EVWXIEQMWGSRWMHIVMRKX[SWMXIW2E[VXL:EPPMWERHNYWXWSYXL[IWX
SJXLIVI4\ME5PERYQ
RSXWLS[R
(VIHMXNASA

TEKIȴȴ•4GXSFIVȶȉȦȮ• EARTH • [[[IEVXLQEKE^MRISVK

Feature