U. Bonnes

Jarosite and Hematite at Meridiani Planum from Opportunity's Mossbauer Spectrometer

Mössbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.

Mössbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits

Additonal co-authors: P Gutlich, E Kankeleit, T McCoy, DW Mittlefehldt, F Renz, ME Schmidt, B Zubkov, SW Squyres, RE Arvidson

The Miniaturized Mössbauer Spectrometer MIMOS II for Extraterrestrial and Outdoor Terrestrial Applications: A Status Report

In May and July 2003 both the European space agency ESA and the American space agency NASA will launch space missions to Mars. The ESA lander Beagle 2 and the two NASAMars-Exploration-Rovers (MER) will explore the Martian surface with a set of sophisticated instruments. Part of the payload will be our miniaturized Mossbauer spectrometer MIMOS II. It operates in backscattering geometry and meets the requirements for space application of low mass (⩽500 g), small volume (coke can size), and low power consumption (⩽3 W). Main goals are the determination of the oxidation state of iron and the iron mineralogy on the surface. This information will contribute to a much deeper understanding of the evolution of the planet Mars, its surface and atmosphere, and the history of water. The MIMOS II flight units for MER were delivered in April 2002 to the NASA Jet Propulsion Laboratories (JPL), California, for integration to the Rovers. After some more testing of the complete Rover system the spacecraft will be shipped to the Kennedy Space Center early February 2003. The first launch will be in May 2003 and the second launch in late June on early July 2003. The flight unit for the ESA Mars-Express Beagle lander was delivered to ESA by the end of May 2002 for integration to the lander in late November/early December 2002. The launch is scheduled for June 2003 from Baikonur, Kazakhstan. The instrument MIMOS II is also under consideration for an ESA space mission to Mercury in 2009, and it is part of the ESA exobiology multi-user facility to be launched as part of one of the next lander Mars missions after 2005.

Polarized Electrons in Darmstadt: Recent Developments

The injector of the superconducting Darmstadt electron linear accelerator S‐DALINAC will soon be extended by a source of polarized electrons. A test set‐up of the future source consists of a 100 keV GaAs polarized gun and associated beamline including an assembly for polarization manipulation and determination. We give a short overview of the existing and planned polarimeters at the different accelerator sites, introduce briefly the future implementation of the polarized source at the S‐DALINAC and list experiments that are planned with polarized electron and photon beams.

Status Report of the New Darmstadt Polarized Electron Injector

We present the status of the polarized injector for the superconducting Darmstadt electron linear accelerator S‐DALINAC. An offline teststand of the source was built to test all components of the S‐DALINAC polarized injector SPIN. The new electron source will deliver a 100 keV polarized beam and complement the present thermionic source operating at 250 kV. Results of the beam properties measurements will be introduced and an outlook on the upcoming installation of the new injector at the S‐DALINAC will be given.

Polarimetry at the Superconducting Darmstadt Electron Linac S‐DALINAC

A spin polarized electron source will be installed at the S‐DALINAC to extend the existing experimental capabilities polarization. In order to manipulate and monitor the beam polarization a Wien filter and different polarimeters will be installed. The already installed Wien filter and 100 keV Mott polarimeter and the planned 5 MeV Mott, 30–130 MeV Mo/ller and Compton transmission polarimeters are described.