Genesis Solar Observation Spacecraft, USA

The Genesis mission, which will be the first to return a space sample to Earth since Apollo 17, is expected to bring back particles from solar winds in space generated by the Sun. Solar wind is one small variable in the growing field of space weather, which mainly focuses on solar flares.

PROJECT RATIONALE

The sponsor of the Genesis solar observation mission is the National Aeronautics and Space Administration (NASA), based in Washington, District of Columbia.

Although the $216 million Genesis mission has unique features, there already are a number of solar-observing satellites in operation, most notably the SOHO satellite, designed to study the internal structure of the Sun, its outer atmosphere and the origin of the solar wind. Genesis will be the first to measure solar winds directly, returning its samples to Earth for analysis. The plan is to measure the abundance of various forms of hydrogen, helium, oxygen and other gases emitted by the sun in the hope of learning about the building blocks of meteors, comets and our solar system.

The mission has three specific main objectives. The primary objective is to obtain a precise measure of solar isotopic abundances. The isotopic compositions of oxygen, nitrogen, and noble gases will be measured in order to enable scientists to better understand the isotopic variations in meteorites, comets, lunar samples, and planetary atmospheres. The second objective is to obtain greatly improved measures of solar elemental abundances. The final objective is to provide a reservoir of solar matter for scientific research, eliminating the need for future solar wind sample return missions.

PROJECT TIMESCALE

Launched in January 2001, the Genesis spacecraft travelled one million miles sunward, which is only 1% of the distance to the Sun. It is now orbiting a gravitational balance point between the Sun and the Earth and has unfolded silicon collectors in which particles will embed themselves. After two years in space, Genesis should return to Earth in 2003. A capsule with the collectors is slated to be rescued by a helicopter from a parafoil plummet over the Utah desert.

GENESIS LAUNCH AND MANOEUVRING

The Genesis mission was fitted on top of a Delta II rocket and launched from the Eastern Test Range at Kennedy Space Center in Florida. The spacecraft is about the size of a dining room table and weighs 414kg.

During the 30 days after the launch there were three trajectory correction manoeuvres to position the spacecraft correctly for insertion into orbit around L1 (the point between the Earth and the Sun where the gravitational forces exerted by each are equal).

After the initial check-out period, the SRC backshell was opened and the parts of the spacecraft surrounding the collectors were allowed to outgas in the vacuum of space. The spacecraft was positioned facing the Sun and the temperature of the solar-facing parts rose to about 200°C. This outgassing procedure is designed to remove the contaminants on the framework and electronic components surrounding the collectors.

COLLECTION OF SOLAR WIND PARTICLES

Collection of the solar wind particles commenced in March, 2001 when the canister cover was opened to expose two of the five collector arrays. The surface of each collector array is an area approximately 3500cm². The science canister also contains a 28cm² concentrator, an electrostatic mirror designed to focus particles on special chemical vapour deposit (CVD) diamond and silicon carbide surfaces.

The two collector arrays exposed by the opening of the canister cover will be deployed during the entire twenty-three months that the solar wind is collected so the concentrator can be exposed. The other three arrays will only be exposed when different regimes of solar wind are active. Once collection is complete, the arrays will pivot back into their original positions and the spacecraft will be ready for the return to Earth.

CONTRACTORS

Jet Propulsion Laboratory of Pasadena, California, is managing the Genesis project.

Lockheed Martin Space Systems Company-Astronautics Operations (LMAO), Denver, Colorado, is the industrial partner. It developed the carrier spacecraft and the sample return capsule, put the components together and tested the entire flight system.

The Space and Atmospheric Science Division of Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, developed the sample concentrator and the two solar wind monitors.

The Johnson Space Centre (JSC), Houston, Texas, prevented and controlled contamination of the solar wind collectors and will safely maintain the returned samples.

Mid-Continent Research for Education and Learning (McREL), Denver, Colorado, is developing and disseminating a wide range of materials for education and public outreach efforts.