NASA has authorized the John Hopkins University Applied Physics Laboratory (APL), Laurel, Md., to proceed with the implementation of the Geospace missions under NASA's existing "Living with a Star" contract with APL. The Living with a Star (LWS) program seeks to address how the variability in the sun affects life on Earth as well as its affect on space weather.

LWS sets out to quantify the physics, dynamics and behavior of the Sun-Earth system over the 11-year solar cycle and improve understanding of solar variability and disturbances on terrestrial climate change. It will also provide data and scientific understanding aimed at developing a predictive capability for space weather affects. In addition, LWS will give scientists a detailed characterization of radiation environments useful in the design of more reliable electronic components for air and space transportation systems.

The two missions assigned to the APL make-up the LWS Geospace Project. These missions were recently identified in a study completed by the Geospace Mission Definition Team, a group tasked by NASA Headquarters to identify LWS Geospace Project goals and priorities. The two missions are the Ionosphere-Thermosphere Mapper Mission (ITM) and the Radiation Belt Mapper Mission (RBM).

The first of these, the ITM mission, will investigate the physical processes that modify and change the Earth's thin outer atmosphere, the region where the planet meets space. The ITM will make measurements of the composition and physical properties of the upper atmosphere between 53-620 miles altitude. Understanding this region of space above Earth, and the sun's effects, will help us with the operation of the International Space Station that operates in this region. It is also a region that modifies the signals of navigation satellites, such as the Global Positioning System.

The Radiation Belt Mission will use two spacecraft in a near equatorial elliptical orbit to take measurements in the space above the ionosphere where the Earth's magnetic field interacts with the magnetic field of the sun. The interaction of these fields of wind provides an energy source for the Earth's magnetosphere and drives a part of the observed variation of the Earth's magnetic field. It is in this region the processes of interaction of the fields of the Earth and sun trap and energizes ions and electrons in radiation belts. The dynamic changes of this region can have important effects on civil and military communications satellite systems.

The ITM and RBM are planned for launch in 2008 and 2010 respectively. The timing is such that the solar magnetic activity cycle, operating with an 11-year period, will be at or near a maximum during these missions. The program is designed to use information at the extreme of this cycle to lead to major advances in our understanding and ability to predict space weather.

The Johns Hopkins University Applied Physics Laboratory in Laurel, Md. is responsible for implementation of the Geospace Project. Implementation includes the design and development of the two spacecraft.

LWS is part of the Sun-Earth Connection theme within the Office of Space Science at NASA Headquarters in Washington. NASA's Goddard Space Flight Center, Greenbelt, Md. manages the LWS program.