Space Test Program-H2-Atmospheric Neutral Density Experiment (STP-H2-ANDE) - 10.21.14
ISS Science for Everyone
Science Objectives for Everyone
Two microsatellites launched from the Shuttle payload bay will measure the density and composition of the low Earth orbit (LEO) atmosphere while being tracked from the ground. The data will be used to better predict the movement of objects in orbit.
Science Results for Everyone
How’s the air up there? Two microsatellites launched from the Shuttle payload bay measured the density and composition of the low Earth orbit atmosphere, collecting data that will help scientists better predict the movement of objects in orbit. The orbital decay of the satellites was tracked by the MAUI Laser Ranging Tracking Station, and, because one satellite carried communications systems operating in the Amateur Satellite Service, ham radio volunteer ground stations provided telemetry feeds, including temperature and battery life.
United States Department of Defense Space Test Program, Johnson Space Center, Houston, TX, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Department of Defense (DoD) - Retired
ISS Expedition Duration
September 2006 - April 2007
Previous ISS Missions
STP-H2-ANDE is a unique investigation that has not been operated in microgravity.
- Atmospheric Neutral Density Experiment (ANDE) objectives are to measure atmospheric density and composition in Low Earth Orbit (LEO) and to better characterize the parameters used to calculate a satellite's drag coefficient.
- This experiment consists of two microsatellites, called Mock ANDE Active (MAA) spacecraft and the Fence Calibration (FCal) spacecraft, that are launched from the Space Shuttle cargo bay.
- These spherical satellites are about 18 inches in diameter and will be tracked by the Satellite Laser Ranging systems and the Space Surveillance Network.
- ANDE is part of the Space Test Program-H2 (STP-H2) complement that also includes MEPSI and RAFT.
ANDE consists of two spherical micro satellites, the Mock ANDE Active (MAA) spacecraft and the Fence Calibration (FCal) spacecraft. These satellites were launched from the space shuttle cargo bay into a circular orbit just below the ISS altitude. The ANDE mission's main objective is to measure the total atmospheric density and composition between 100 and 400 km. The density data that is gathered will be used to better characterize the parameters used to calculate a satellite's drag coefficient and improve orbit determination calculations of resident space objects.
Both satellites will be tracked by the Satellite Laser Ranging (SLR) system and the U.S. Space Surveillance Network (SSN). These satellites have similar dimensions, but are constructed of different materials and have different masses. Because of the difference in mass, the satellites will drift apart over time. Observing the satellites' position will provide a study on spatial and temporal variations in atmospheric drag associated with geomagnetic activity. The FCal sphere will also be used to perform calibrations for the U.S. Radar Fence.
Understanding the atmospheric effects on spacecraft in Low Earth Orbit will lead to improved calculations for orbit determinations and collision avoidance.
Improving calculations that are used when observing orbits, may lead to advancements in the fields of mathematics and physics here on Earth.
ANDE uses two spherical micro satellites, the Mock ANDE Active (MAA) and the Fence Calibration (FCal), which are launched from the Space Shuttle cargo bay. The MAA satellite is a 19 inch diameter sphere, has a mass of 50 kg, and is constructed of aluminum. The surface of the MAA sphere contains an embedded array of sensors including 30 retro reflectors, six laser diodes for tracking, and six photovoltaic cells for determining orientation and spin rate. The FCal satellite is 17.5 inches in diameter, has a mass of 75 kg, and is constructed of nickel-plated brass. The FCal spacecraft is also fitted with 30 retro reflectors, six phototransistors, and four whip antennae. Both spheres also have thermal monitor systems. The ANDE spacecraft are located inside the Internal Cargo Unit (ICU). The ICU is made of three aluminum sections. Each section is separated by a light band separation system. Once ejected from the cargo bay, the ICU will separate and deploy the ANDE spheres at a safe distance from the shuttle.
ANDE will be launched from the Space Shuttle cargo bay. The two micro satellites will be contained inside the ICU canister. Once the ICU canister is a safe distance from the Space Shuttle, two micro satellites will be released at an altitude of approximately 350 km.
The ANDE satellite re-entered the earth’s atmosphere on December 25, 2007, over a year after deployment. Its orbital decay was tracked by the MAUI Laser Ranging Tracking Station. Because the satellite carried packet radio communications systems operating in the Amateur Satellite Service, ham radio volunteer ground stations were critical for telemetry feeds that included temperature and battery life. (Evans et al. 2009)
Ground Based Results Publications
Nicholas A, Budzien SA, Healy L, DeYoung J, Davis M. Results from the Atmospheric Neutral Density Experiment Risk Reduction Mission. AIAA/AAS Astrodynamics Specialist Conference and Exhibit, Honolulu, HI; 2008
ANDE, RAFT, NMARS, & FCAL Operations
Representation of the micro satellite Fence Calibration (FCal). Image courtesy of NASA, Johnson Space Center.
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The Mock ANDE Active (MAA) spacecraft, pictured here, will be launched from the space shuttle cargo bay. Image courtesy of NASA.
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NASA Image: S116E07828 - This image of the ICU (Internal Cargo Unit) was taken immediately following launch from the Canister for All Payload Ejections (CAPE) located in the cargo bay of the Space Shuttle Discovery during the STS-116. The second satellite did not leave its half of the ICU until four hours later.
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NASA Image: S116E07836 - Shown is one of the ANDE satellites floating free from the ICU (Internal Cargo Unit) after deployment. The second satellite did not leave its half of the ICU.
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