Delta Launches NASA, Argentina and Swedish Science Satellites

A Delta 2 7320-10 successfully launched Earth Observing-1, SAC-C, and Munin, from Vandenberg Air Force Base, pad SLC 2W, at 1824:25 UTC (10:24 a.m. PST) on November 21, as a short 22-second launch window opened. Earth Observing-1 (EO-1) is the first satellite in NASA's New Millennium Program Earth Observing series. Satelite de Aplicanciones Cientificas-C (SAC-C) is a joint Argentina/NASA flight. The Munin nanosatellite is sponsored by the Swedish Institute of Space Physics. The flight was originally scheduled to also carry Citizen Explorer 1 (CX-1), but the microsatllite was removed from the manifest because it did not meet the deadline for integration on the launch vehicle. 

The primary focus of the US$193 million satellite is to develop and test a set of advanced technology land imaging instruments. EO-1 will be inserted into an orbit flying in formation with the Landsat 7 satellite taking a series of the same images. EO-1 will fly in a 705 km (381 nmi) circular, sun-synchronous orbit at a 98.7 degree inclination. This orbit will allow EO-1 to match within one minute, the Landsat 7 orbit and collect identical images for later comparison on the ground. Once or twice a day, sometimes more, both Landsat 7 and EO-1 will image the same ground areas (scenes). All three of the EO-1 land imaging instruments will view all or subsegments of the Landsat 7 swath. Comparison of these "paired scene" images will be one means to evaluate EO-1's land imaging instruments. Reflected light from the ground will be imaged onto the focal plane of each instrument. Each of the imaging instruments has unique filtering methods for passing light in only specific spectral bands. Bands are selected to best look for specific surface features or land characteristics based on scientific or commercial applications.

Many other key instruments and technologies are part of the EO-1 mission and will have wide ranging applications to future land imaging missions in particular and future satellites in general. Three land imaging instruments on EO-1 will collect multispectral and hyperspectral scenes over the course of its mission in coordination with the Enhanced Thematic Mapper (ETM+) on Landsat 7. Breakthrough technologies in lightweight materials, high performance integrated detector arrays and precision spectrometers will be demonstrated in these instruments. Detailed comparisons of the EO-1 and ETM+ images will be carried out to validate these instruments for follow-on missions.

The 529 kg (1166 lbm) EO-1 spacecraft bus was provided by Swales Aerospace, Beltsville, Maryland. The EO-1 spacecraft bus has heritage with the MIDEX spacecraft bus. Swales Aerospace is an employee-owned small aerospace engineering firm with expertise in mechanical, thermal, optical, electrical systems, guidance and controls, mission operations, graphics and computer support, and the design, development, and production of spacecraft, instruments, and mechanisms. Swales also designs and manufactures specialty flight hardware including space-qualified passive thermal louvers, thermal heat pipes, capillary pumped loops, deployable radiators, astronaut tools, composite structures, calorimeters, and magnetometers. Swales Aerospace was originally in 1978 as Swales & Associates, Inc. to provide aerospace engineering services to the Goddard Space Flight Center. 1998 revenues exceeded US$85 million.

The US$45 million SAC-C mission is led by CONAE, Argentina’s space agency, with NASA and the space agencies of Denmark, Italy, Spain, France, and Brazil. INVAP is the prime contractor for the design and construction of the SAC-C spacecraft and its main payload, a Multispectral Medium Resolution Scanner as well as a High Sensitivity Medium Resolution Camera.

The 425 kg satellite will provide data for the study of terrestrial and marine ecosystems, atmospheric temperature and water vapor monitoring. SAC-C will determine variability in the ionosphere structure, providing space observatory quality measurements of the geomagnetic field and measurements of the long wavelength component of the gravitational field. The satellite will also update low orbit space radiation environment models. The spacecraft’s launch configuration is 2.1 x 1.9 x 1.7 m (6.8 x 6.1 x 5.4 ft). 

The 6 kg Munin nanosatellite is sponsored by the Institutet för RymdFysik (Swedish Institute of Space Physics), Umeå University and and Luleå University of Technology. The scientific objective is to collect data on the auroral activity for both the northern and southern hemispheres, such that a global picture of the current state of activity can be made available on-line. The data acquired by Munin will then serve as an input to the prediction of space weather.

The satellite uses a passive magnetic stabilization system, a permanent magnet holds the satellite aligned along the geomagnetic field lines (like a compass needle). The satellite has no moving parts, deployable booms, etc. The stowed dimension of the satellite is 20 x 20 x 25 cm. The satellite is covered with solar cells on all surfaces. The satellite is powered by the solar cells, which provide enough power when the satellite is in sunlight to also recharge a battery that will keep the satellite powered when it is in eclipse.

Munin was placed in an elliptical orbit, 698 x 1810 km (377 x 977 nmi), at 95.4 degrees inclination.  In the orbit it collects information about the distributions of electrons and ions and stores this in the onboard (2Mb) RAM. By using artificial intelligence and compression methods we can be sure of only storing interesting data. This data is downlinked with use of a radio modem when the satellite passes Kiruna, Sweden, and will be made available on the world wide web immediately after reception.

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