Welcome to ASPERA-3, the first Mission of Opportunity to be selected as part of the Discovery Program. The ASPERA (Analyzer of Space Plasmas and Energetic Atoms) experiment is one of seven scientific instruments that will fly on the European Space Agency's (ESA) Mars Express mission, planned to launch in mid-2003. The main objective of the mission is to search for sub-surface water from orbit and drop a lander on the Martian surface. The instruments onboard the orbiting spacecraft will perform remote sensing measurements designed to answer questions about the Martian atmosphere, the planet's structure and geology. The Mars Express team consists of ESA engineers, industry and hundreds of international scientists.

ASPERA-3 will study how particles ejected from the Sun, called solar wind, interact with the Martian atmosphere. This should shed new light on the mechanisms by which water vapor and other gases could have escaped from Mars in the past. The instrument will use a technique known as Energetic Neutral Atom (ENA) imaging to visualize the charged and neutral gas environments around Mars. The Swedish Institute of Space Physics is leading the development of ASPERA-3.

The ASPERA-3 has four sensors to gather the data, along with the data processing unit and the scanning platform (see illustration). Two of the sensors, the Electron Spectrometer (ELS) and the Ion Mass Analyzer (IMA) Imaging Detector, are being funded by NASA as a Discovery Mission of Opportunity. The IMA is a separate unit connected by a cable to the ASPERA-3 experiment. They will be built by Southwest Research Institute of San Antonio, Texas, led by John Scherrer, Project Manager, and David Winningham, Principal Investigator.

At an October 21 Confirmation Review at NASA Headquarters, ASPERA was given approval to move into the implementation phase, with two conditions relating to documentation that should be completed within 30 days.

To learn more about Discovery Missions of Opportunity, see Get Involved.

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