Tuesday, February 27, 2007

Rosetta's Mars Swingby > ROMAP Update

Following the successful Mars Swingby performed by ESA’s Rosetta, and after yesterday's talk with Jean-Pierre Bibring, today spacEurope posts a Q'n'A with Ulrich Auster, co-Principal Investigator from the Technische University, Braunschweig, Germany, for ROMAP (Rosetta Lander Magnetometer and Plasma Monitor onboard the Philae Lander).
Read how precious lessons were learned for future observations.

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What is the importance of ROMAP observations (which goal is to study the local magnetic field of Comet 67P/Churyumov-Gerasimenko and examine the intensity of the magnetic interaction between the comet and the solar wind in three spatial dimensions)? What might we learn in terms of future space exploration?


The visible parts of a comet, coma and tail, depend on the outgas rate of the nucleus. The gas will be ionised by UV radiation and interacts with the solar wind plasma. The outgas rate of a comet increases with its vicinity to the Sun. With Rosetta we have the unique possibility to investigate the onset of this interaction process from a very large distance (3.5AU) to near Earth distance (1AU). After landing of Philae the observation can be done in parallel on the comet and at various distance to the comet by the Orbiter. Furthermore we can investigate the magnetic properties of the comet during the descent phase of the Philae. Magnetic forces could accelerate the aggregation process of dust grains due to its large scattering cross section. If this process contributes to the formation of comets magnetisation should remains. Also this could be investigated by ROMAP for the first time.

The graphic from the observations presented in an ESA update shows how the magnetic environment of Mars becomes complex...What are the consequences at the surface resulting from this? What might be the benefits of ROMAP's magnetic fields observations regarding future manned missions to Mars?

Due to the absence of a global magnetisation of Mars the solar wind is decelerated and diverted in a distance of only some hundreds of km from the surface (at Earth the magnetic dipole field stops the solar wind in a distance of 60000km). Nevertheless the so called induced magnetosphere protects also Mars from direct access of the solar wind particles, but solar wind can be turbulent and plasma boundaries are variable. The investigation of these “complex” system tells us how the energy of the solar wind penetrates into the Martian system. Especially the tail region (crossed by Rosetta) is of interest because in this region plasma can be accelerated. For future manned mission to Mars particle flows have to be considered, however in the ranking of potential risks this will be not the first one.

Everything went according to what was expected. Is it possible to improve ROMAP's capabilities now that we know that it is in perfect shape or what we see is what we have?
Was there something that the team learned that can be useful for the upcoming comet's observations?

During the closest approach the Lander operates autonomously: the Lander was powered by its batteries, data are stored in its internal memory, CIVA and ROMAP are the only instruments which are switched on. This was the first time that a scenario, very similar to that during the descent phase, was tested inflight. Although ROMAP samples magnetic field vectors in the fastest rate, we missed no single bit on ground. This demonstrates the reliability of all involved Lander systems (board computer, power supply, thermal control unit) as well as the perfect operation control and data handling. Finally we learned, that magnetic interferences e.g. due to different CIVA modes can be handled by data reprocessing on ground.

Any unexpected surprise from the observations?

It is always a positive surprise to get new data from a far distant place.

Will ROMAP enter in action again during the next Earth swingby? Or will be there different observations on that occasion?

The incoming trajectory of the next Earth flyby is very of interest for plasma investigation. The magneto-tail is like a kitchen for plasma processes. Reconnection of field lines accelerate plasma toward the Earth. Magnetic sub-storms which provide us turbulent auroras, have its sources in the magneto-tail. The Rosetta mission gives us the opportunity to measure along the tail from a distance of 200 Earth radii up the radiation belt. In combination with other spacecrafts like Cluster (1-4) or Themis (1-5) we have a fantastic constellation to measure plasma parameter at the same time at different positions.

What will be the team's work untill 2014? Analyze Mars data and?...

Our team is specialised on magnetic field measurements. The principle of a fluxgate magnetometer is simple – the construction manual can be downloaded. To design a magnetometer which meets the requirements on harsh space environment without any lost of stability and resolution is a complete different thing. You have to work continuously over years. Our sensor specialist send his first ringcores already in the late eighties into space. Furthermore expensive test facilities are necessary for calibration and simulation of a space like environment. Cooperation with other magnetometer teams like those in Graz and London, as well as a number of mission participations are necessary. Magnetometers onboard Venus Express, Themis and in future onboard BepiColombo, are very similar to that on Rosetta.

Did you already get some sleep since Sunday?

I slept like a log.

More at
ESA.int

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