[meteorite-list] Landing Site Recommended for ExoMars 2018

[Ron Baalke]

http://www.esa.int/Our_Activities/Space_Science/Landing_site_recommended_for_ExoMars_2018

Landing Site Recommended for ExoMars 2018
European Space Agency
21 October 2015

Oxia Planum has been recommended as the primary candidate for the landing 
site of the ExoMars 2018 mission.

ExoMars 2018, comprising a rover and surface platform, is the second of 
two missions making up the ExoMars programme, a joint endeavour between 
ESA and Russia's Roscosmos. Launch is planned for May 2018, with touchdown 
on the Red Planet in January 2019.

Meanwhile, the Trace Gas Orbiter and the Schiaparelli entry, descent and 
landing demonstrator module will be launched in March 2016, arriving at 
Mars around this time next year.

Schiaparelli will land in Meridiani Planum. The orbiter will study the 
atmosphere and act as a relay for the second mission.

The search for a suitable landing site for the second mission began in 
December 2013, when the science community was asked to propose candidates. 
In October 2014, the Landing Site Selection Working Group chose four sites. 
The last year has been spent evaluating these sites, taking into account 
the engineering constraints of descent and landing, and the best possible 
scientific return of the mission

The main goal for the rover is to search for evidence of martian life, 
past or present, in an area with ancient rocks where liquid water was 
once abundant. A drill is capable of extracting samples from up to 2 m 
below the surface. This is crucial, because the present surface of Mars 
is a hostile place for living organisms owing to the harsh solar and cosmic 
radiation. By searching underground, the rover has more chance of finding 
preserved evidence.

Scientists believe that primitive life could have gained a foothold when 
the surface environment was wetter, more than 3.6 billion years ago. Buried 
or recently exhumed layered sedimentary deposits thus offer the best window 
into this important period of Mars history.

ExoMars 2018 landing site candidates

All four sites under study - Aram Dorsum, Hypanis Vallis, Mawrth Vallis 
and Oxia Planum - show evidence of having been influenced by water in 
the past, and are likely representative of global processes operating 
in the Red Planet's early history.

All locations offer the opportunity of landing at a scientifically interesting 
site or finding one within a 1 km drive from the touchdown point, with 
numerous targets accessible along a typical 2 km traverse planned for 
the mission of 218 martian days (each 24 hours 37 minutes).

The sites must also conform to strict engineering constraints to ensure 
the safe entry, descent and landing of the entry module. These include 
the need for a relatively low-lying site, in order that the module passes 
through enough atmosphere for the completion of key events such as parachute 
opening and deceleration.

The horizontal and vertical wind speeds expected during the descent must 
also be also considered - it will land at the end of the planet's 
global dust storm season in 2019.

Knowledge of how the terrain slopes over various scales is important, 
because the lander uses radar to monitor its velocity and altitude. Slopes 
can alter the degree of certainty in the measured distance to the ground, 
with implications for fuel consumption and landing.

Steep slopes and boulders taller than 35 cm - the clearance beneath 
the landing module - need to be avoided, although the rover will be 
able navigate around local hazards after egress.

Taking into account these requirements and the individual science cases 
put forward for each site, the Landing Site Selection Working Group today 
recommended that Oxia Planum be the primary focus for further detailed 
evaluation for the 2018 mission.

A further recommendation was made to also consider Oxia Planum as one 
of the two candidate landing sites for the backup launch opportunity in 
2020, with a second to be selected from Aram Dorsum and Mawrth Vallis.

"Our preliminary analysis shows that Oxia Planum appears to satisfy 
the strict engineering constraints while also offering some very interesting 
opportunities to study, in situ, places where biosignatures might best 
be preserved," says Jorge Vago, ESA's project scientist.

Oxia Planum contains one of the largest exposures of rocks on Mars that 
are around 3.9 billion years old and clay-rich, indicating that water 
once played a role here.

The site sits in a wide catchment area of valley systems with the exposed 
rocks exhibiting different compositions, indicating a variety of deposition 
and wetting environments.

A period of volcanic activity may have covered early clays and other aqueous 
deposits, offering preservation for biosignatures against the planet's 
harsh radiation and oxidation environment, and have only been exposed 
by erosion within the last few hundred million years.

"Compared with landing site selection for previous missions, which relied 
primarily on the morphology of candidate sites alone, we are today in 
a much better position to understand the mineralogy of the various sites," 
adds Jorge.

"This puts us in the best position to choose sites that offer access 
to the most ancient, pristine material that not only preserves a record 
of early Mars but which is globally representative of processes occurring 
across the planet.

"It made for a challenging decision today, given the quality of the 
cases for all sites, but we are looking forward to the next stage of analysis 
as we move closer to the launch of our exciting mission: our rover will 
search for molecular biosignatures in the subsurface for the very first 
time."

Selection of the final landing site by ESA and Roscosmos is planned to 
occur six months before launch.

Notes for Editors

Detailed descriptions of all four candidates are available here:
Aram Dorsum
Hypanis Vallis
Mawrth Vallis
Oxia Planum

More information about the Landing Site Selection Working Group is available 
here.

For further information, please contact:
Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer at esa.int

Jorge Vago
ESA ExoMars 2018 project scientist
Scientific Support Office, Directorate of Science and Robotic Exploration
Tel: +31 71 565 5211 / +31 6 27 65 87 70
Email: jorge.vago at esa.int