Mars Express PFS spectrometer back at work (Forwarded)

ESA News
http://www.esa.int

2 November 2005

Mars Express PFS spectrometer back at work

The Planetary Fourier Spectrometer (PFS) on board ESA's Mars Express spacecraft is now back in operation after a malfunction, reported a few months ago.

The instrument had been successfully investigating the chemical composition of the Martian atmosphere since the beginning of 2004, when Mars Express began orbiting the Red Planet.

PFS is a very sensitive instrument, capable of measuring the distribution of the major gaseous components of the atmosphere, the vertical distribution of their temperature and pressure, and determining their variation and global circulation during the different Martian seasons.

PFS is also capable of detecting minor gaseous species and the presence of dust in the atmosphere and, during favourable observing conditions, even deducing the mineralogical composition of the soil.

PFS was the first instrument ever to make direct 'in situ' measurements of methane in the atmosphere of Mars, and provided first indications of traces of formaldehyde, both candidate ingredients for life.

To identify the nature of chemical compounds of the Martian atmosphere and their physical status, PFS detects the distinctive infrared radiation re-emitted by different molecules when they are exposed to the light of the Sun.

The complex PFS instrument uses the interferometry technique, a high-precision measurement method in which beams of electromagnetic radiation are split and subsequently recombined after travelling different path-lengths. The beams interfere and produce an 'interference pattern'.

This pattern, or 'interferogram', is then used to measure physical properties such as temperature, pressure and chemical composition.

The PFS instrument was unable to produce scientific data from July to September 2005. A series of tests and investigations took place between September and October this year.

The 'pendulum motor', used to drive various elements in the instrument optics, was shown to be at fault. The recovery was made possible through using internal instrument redundancy.

After switching to the instrument's back-up motor, more powerful than the first one -- the instrument has been shown to be able to produce science data just as before. Following this recovery activity, PFS will start to take new measurements routinely in early November 2005.

Notes to editors:

PFS is a 'double pendulum' interferometer. The incident radiation is divided into two beams by a mirror and then filtered before being directed into two separate interferometers. The interferometers are positioned with their planes of operation one above the other so that a single motor can be used to move both pendulums.

PFS measurements have a spatial resolution ranging from 7 to 12 kilometres when Mars is observed from an altitude of 250 kilometres.

For more information:

Prof. Vittorio Formisano, PFS Principal Investigator
IFSI-CNR, Rome, Italy
E-mail: formisan @ nike.ifsi.rm.cnr.it

Fred Jansen, ESA Mars Express Mission Manager
E-mail: fjansen @ rssd.esa.int

Agustin Chicarro, ESA Mars Express Project Scientist
E-mail: agustin.chicarro @ esa.int

Enrico Flamini, ASI Mars Express Mission Manager
E-mail: enrico.flamini @ asi.it

More about...

* Looking at Mars
  http://www.esa.int/SPECIALS/Mars_Express/index.html
* Orbiter instruments
  http://www.esa.int/SPECIALS/Mars_Express/SEMUC75V9ED_0.html

Related articles

* Mars Express instrument under investigation
  http://www.esa.int/esaCP/SEMSEK7X9DE_index_0.html
* Mars Express confirms methane in the Martian atmosphere
  http://www.esa.int/esaCP/SEMZ0B57ESD_index_0.html
* Chances of life are linked to water
  http://www.esa.int/esaSC/SEMN3AR1VED_index_0.html
* Geography of Mars
  http://www.esa.int/SPECIALS/Mars_Express/SEMWPNXLDMD_0.html

Related links

* Planetary Fourier Spectrometer
  http://www.pfs-results.it
* High Resolution Stereo Camera
  http://berlinadmin.dlr.de/Missions/express/indexeng.shtml

IMAGE CAPTION:
[http://www.esa.int/esaCP/SEM6N9638FE_index_1.html]
ESA's first mission to the Red Planet, Mars Express, was launched in June 2003. It comprised an orbiter carrying seven scientific instruments to probe the planet's atmosphere, structure and geology, including a search for evidence of hidden water. The main spacecraft released the UK's small Beagle 2 lander to gather and test rock and soil samples on the surface. As well as its science objectives, Mars Express also provides relay communication services between Earth and landers deployed on the surface by other nations, thus forming a centrepiece of the international effort in Mars exploration.

Mars Express is a pilot project for new methods of funding and managing ESA space missions, built more quickly and launched at a much lower cost than any previous mission of a similar nature.

Credits: ESA
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