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Mission Photos:
ANDE Satellites

ANDE-2 Spheres CASTOR (left) and POLLUX (right).
Courtesy of NRL

ANDE Shuttle Deployment photos Courtesy of NASA

ANDE deployment
Shuttle deployment
(NASA image ID s127e012318)

ANDE separation
(NASA image ID s127e012911)

ANDE separation
(NASA image ID s127e012919)

ANDE Pollux
(NASA image ID s127e012928)

ANDE Pollux and Castor
Pollux and Castor
(NASA image ID s127e012938)
Mission Objectives:

The Atmospheric Neutral Density Experiment (ANDE) flight is a mission flown by the Naval Research Laboratory to monitor the thermospheric neutral density at an altitude of 350km. The mission will be launched from the Space Shuttle in May 2009 and will measure the density and composition of the low Earth orbit atmosphere while being tracked from the ground to better predict the movement and decay of objects in orbit.

The ANDE mission consists of two spherical microsatellites fitted with retroreflectors: ANDE Active spacecraft (Castor) and the ANDE Passive spacecraft (Pollux). The satellites are identical in dimension (diameter of 19 inches), but have different masses, and will be tracked by the ILRS network as well as the Space Surveillance Network (SSN). The spheres will be in a lead-trail 400 km, 51 degree inclination orbit. Because of the difference in mass, the satellites will drift apart over time. The position observations of the satellites will permit studies on spatial and temporal variations in atmospheric drag associated with geomagnetic activity. Scientific objectives include:

  • Provide Total Atmospheric Density for Orbit Determination and Collision Avoidance
  • Validate Fundamental Theories on the Calculation of the Drag Coefficient
  • Provide Calibration Objects for SSN
  • Establish a Method to Validate Neutral/Ion Density and Composition Derived from DMSP Sensors
  • Space to Ground Optical Communication Experiment

The passive sphere (Pollux) wase observed with SSN and SLR. The variation in the observed position will be used to determine in-track total density. Tracking of the active sphere (Castor) will be used to determine its position with respect to the passive sphere. On-board instrumentation will compute total density and composition.

The last observation of the ANDE Pollux spacecraft was on 28-Mar-2010 at 22:55 from the Beale Phased Array (west coast of CONUS), Shortly after, the spacecraft re-entered the Earth's atmosphere.

Mission Instrumentation:

ANDE has the following on-board instrumentation and components:

  • Active Sphere:
    • Retro-Reflector Array
    • GPS
    • Wind and Temperature Spectrometer (WATS) for measuring ion and neutral winds and temperature
    • Thermal Monitoring System (TMS) for monitoring internal and skin temperature
    • Miniature Electronic Analyzer (IMESA) for measuring electron density and temperature
    • Photovoltaic Arrays
    • 3 Gyroscopes and 3 MEMS accelerometers for determination of spin rate and orientation
  • Passive Sphere:
    • Retro-Reflector Array
    • 3 Gyroscopes and 3 MEMS accelerometers for determination of spin rate and orientation
Mission Parameters:
  ANDE Active (Castor) ANDE Passive (Pollux)
Sponsor: NRL NRL
Expected Life: 1 year 1.5 year
Primary Applications: determine total atmospheric density in orbital plane determine total atmospheric density in orbital plane
Primary SLR Applications: Precision orbit determination Precision orbit determination
COSPAR ID: 0903806 0903805
SIC Code: 1073 1074
Satellite Catalog (NORAD) Number: 35694 35693
Launch Date: July 30, 2009 July 30, 2009
RRA Diameter: 12.7 mm 12.7 mm
RRA Shape: sphere sphere
Reflectors: 30 corner cubes 30 corner cubes
Orbit: circular, non sun-synchronous circular, non sun-synchronous
Shape: 19.0 inch diameter sphere 19.0 inch diameter sphere
Inclination: 51.6 degrees 51.6 degrees
Eccentricity: 0.0007 0.0007
Altitude: 350 km 350 km
Weight: 50 kg 25 kg

Additional Information:

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