Pod landers

The landers covered in this chapter have the ability to survive an initial landing impact, which may send the vehicle rolling and/or bouncing across the surface, and then commence operations having come to rest in whatever orientation is finally reached. Most achieve this by means of airbags to cushion and dampen the initial impact and subsequent rolling/bouncing motion, followed by the opening out of a system of 'petals' to bring the lander itself to its proper orientation for surface operations. The Ranger seismometer capsules are the exception to this; their impact damping was provided by the balsa-wood shell and liquid-bath system surrounding the experimental equipment, and the orientation being achieved by means of the natural position of the equipment within its liquid bath.

Typical payload experiments for such landers include cameras, meteorological, geological, geophysical and environmental sensors for investigation of the landing site. While some can be body-mounted on the probe, others may require deployment by means of masts, arms or a rover. In the case of the Mars Exploration Rovers, the pod landing stage itself plays no further role once the rover has rolled off.

Pod landers are particularly suited to 'network science', where simultaneous seismological, meteorological or other geophysical measurements are made at multiple locations. Such a network was the aim of the NetLander mission12 a network of four Mars landers to be carried on the CNES-led Mars Premier mission. The mission was cancelled in 2003 towards the end of Phase B of the project, however.

At the time of writing, ESA is planning the ExoMars mission, which will send a rover to Mars to search for evidence of life and to assess possible hazards for human exploration. The rover would be deployed in a similar fashion to the Mars Exploration Rovers, namely by means of a three-petalled

12 The payload of each of the four NetLanders was as follows: ATMIS (Harri), ARES (Berthelier), GPR (Berthelier), MAGNET (Menvielle), NEIGE (Dehant), PANCAM (Jaumann), SEIS (Lognonne), SPICE (Spohn), MIC (Delory). The Project Scientist was Jean-Louis Counil.

pod lander. However, following roll-off of the rover, the landing stage may also incorporate long-term geophysical measurements, using payload heritage from a number of previous projects including NetLander, Beagle 2 and the cancelled Mercury Surface Element of the ESA-led BepiColombo mission.

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