ASPERA-3: Analyzer of Space Plasmas and EneRgetic Atoms

ASPERA-3  -  a MarsExpress Orbiter Instrument

Analyzer of Space Plasmas and EneRgetic Atoms

ASPERA-3 logo ASPERA-3 is an advanced and compact ion, electron and neutral particle detector package developed for the MarsExpress mission to investigate the plasma and neutral particle environment near Mars. ASPERA-3 will perform the first ever Energetic Neutral Atom (ENA) measurements at another planet in the low energy range (100 eV - 10 keV).


> Science objectives
> Instrument description
> MPS contribution
> Neutral Particle Detector (NPD)
> Neutral Particle Imager (NPI)
Email Joachim Woch
Email Markus Fraenz
> Related links
> ASPERA-3 publications by MPS members

Science objectives

The general scientific objective of ASPERA-3 is to study the solar wind - atmosphere interaction and to characterize the plasma and neutral gas environment in the near-Mars space through >Energetic Neutral Atom (ENA) Imaging and in-situ plasma measurements. ENA imaging is a novel technique to visualize and monitor processes in dilute gases. ENAs are produced via charge exchange processes between singly-charged ions and neutral gases of the exosphere / upper atmosphere. Due to their neutrality, ENAs are decoupled from the electromagnetic fields and propagate on straight paths like photons. Directional detection of the ENAs therefore yields a global image of the interaction region.

The specific objectives are:

The studies to be performed address the fundamental question: How strongly do the interplanetary plasma and electromagnetic fields affect the Martian atmosphere? This question is directly related to the problem of Martian dehydration. Where is the water? Is it lost or frozen? If it is the former, what could produce such an effective escape mechanism? If it is the latter, where is the tremendous amount of water stored? Since liquid water is the fundamental requirement for life, a clear understanding of the fate of the Martian water is a crucial issue in resolving the problem whether or not life existed on Mars in the past. No instruments with similar scientific objectives and capabilities have been or are planned to be flown to Mars.


Instrument description

ASPERA-3 comprises four sensors:

To increase angular coverage NPI, NPD, and EIS are mounted on a scanning platform.

ASPERA-3 performance

Particles ENA ENA ions electrons
Energy, keV 0.1 - 60 0.1 - 10 0.01 - 40 0.001 - 20
Energy res. dE/E - 80% 10% 7%
Mass res. - H, O M/dM = 5 -
FoV 9 x 344 9 x 180 4.6 x 360 10 x 360
Angular Res. (FWHM) 4.6 x 11.5 5 x 30 5 x 22.5 5 x 22.5
G-Factor/pixel, cm2 sr 2.5 x 10-3 6.2 x 10-3 3.5 x 10-4 3 x 10-4
Efficiency, % 1 1 - 25 n/a n/a
Time res. for full 3D, s 32 32 32 32


MPS contribution

ASPERA-3 is realized by a large international consortium of more than 10 European and US institutes. The >team is led by R. Lundin (Swedish Institute of Space Physics, Kiruna). The MPS, in cooperation with IDA (University Braunschweig) and IFSI, Rom, is supplying the electronics of the NPD sensor and will take part in the scientific data analysis.


Related links

> Swedish Institute of Space Physics
> Aspera-3 site at IRF

2006, Max Planck Institute for
Solar System Research, Lindau