The NetLander mission aims at deploying on the surface of Mars a network of 4 geophysical
and meteorological landers implemented by the CNES and realized by
a European and American consortium : Finland (FMI),
Germany (DLR), Belgium
(SSTC PRODEX), Switzerland (PRODEX)
and USA (JPL).
The launch of the four landers is planned in 2007, as the same time as the sample return
NASA / CNES mission, on Ariane 5. This mission will allow to study :
- Deep internal structure
- Global atmospheric circulation
- Planetary boundary layer phenomena
- Subsurface structure at the km scale, down to water rich layers
- Surface mineralogy and local geology
- Alteration processes and surface/atmosphere interaction
The mission development
The four NetLander landers will be separated during the 3 last weeks from the MSR orbiter and directly injected to Mars. Protected by their shield, they will enter the atmosphere with a speed of 6 km/s and will be slowed down by atmosphere.
A first then a second parachute will end deceleration, then an airbag will be blown up to protect from the final hit during the ground impact. During this impact, their speed will be around 70 km/h, and the shock will be similar to a car hitting a wall at the same speed. After several bounces (the first one may reach at least 50 m), the landers will stop, airbag will be blown off. The station will first deploy its solar panels, its telecommunication antenna, then its scientific instruments.
A few NetLanders characteristics
- Entering shield diameter : 90cm
- Airbag diameter : 110cm
- Non deployed station diameter : 47cm
- Camera arm diameter : 70cm
- Playload mass : 4.5kg
- Ground mass : 17.5kg
- Ejected mass : 47.5kg
- Mass on Ariane 5 : 210kg
More information ?
- Site of the CNES NETLANDER Project
Scientific objectives and scientific playload
The scientific playload of NetLander was chosen to answer a few fundamental questions about Mars, particularly :
Is there liquid water in the martian underground ?
Under each lander, combined instruments will carry out detection of an eventual liquid water
reservoir up to several kilometers deep :
- a radar will execute an active electromagnetic sounding,
- a magnetometer will detect ground telluric currents, very strong in a conducting environment such as water,
- a short-period seismometer will study the seismic attenuation under the lander.
How was Mars formed ? Which differences with the Earth' internal structure ?
At a global level NetLander network, thanks to the geodesic experiments (with the radio system), to the seismologic experiments (with a very broad band seismometer), and to the magnetism experiments (with the magnetometer), will allow to determinate how do vary volumic mass, seismic velocities and electric conductivity with depth. The goal is to determine the martian core diameter and its state (liquid or solid). Another goal is to find chemical composition of Mars' mantle and to detect the phase transformations according to depth. Knowledge of the planet internal structure will carry out a complete inventory of its component material. It will be thus possible to compare primary material, chemical composition, and formation processes of two telluric planets situated at different distances from the Sun.
Theoretical models forecast that the slow cooling of the planet could generate a great number of marsquakes : about 50 seisms of magnitude over 3.5 per year. Seismic waves don't spread with the same speed through layers with different chemical composition. Seismograms analysis will inform us on the internal composition of the planet. Another way to proceed will be to measure tides produced by Phobos, one of Mars' moons. Those tides are 10 times lower than the tides produced by the Earth' Moon.
What is the martian meteorology ? How to compare it with the Earth' one ?
Four sites (one of them located in the south hemisphere) will be selected for NetLander meteorological measurements. Pressure, temperature, humidity, wind speed and direction, optical thickness, atmospheric electric field will be measured on each point by a meteorological station. It will then be possible to study Mars meteorology and to compare it with Earth' one, in order to understand better the evolution and dynamics of planetary atmospheres.
Existence of strong electric fields in the martian atmosphere is highly suspected. Their measurement by an electric sensor will improve our understanding :
What is the surface geology and how do atmosphere interact with surface ?
- of atmosphere and surface physical chemistry,
- of the atmosphere carrying dust phenomena, particularly during storms.
The four landing sites geology and mineralogy will be studied by a stereoscopic multispectral camera. That will allow to study :
- the sites' geological history,
- far landscape morphology and adjustment with orbital imaging,
- dunes morphology and rocks distribution,
- ground rocks size, form, texture and roughness,
- rocks approached mineralogy,
- erosion phenomena and frost deposit.
To know more about
Instruments on each NETLANDER.
Comparison between Earth and Mars. Mars' mantle is compared to the Earth' superior mantle.
Phobos, one of the two martian moons. Its altitude is around 6.000km, i.e. 6 times less than geostationary telecommunication satellites around Earth. Image size : 8km x 12km.
It will be also possible to measure the precession of Mars' equinoxes, i.e. the slow drift of the planet rotating axe. This measurement will teach us about the core mass and its sate, liquid or solid.
Pressure cycle measured by the two VIKING landers.
At the ground, storms may cause deep decreases of luminosity and temperature.
Dust storm on Mars (view from the VIKING orbiter).
Carbonic gas frost ground deposit in the early hours (view by one of the VIKING landers).