Nanosatellite: Size Matters
Back at the dawn of the Space Age in 1958, the limited “throw-weight” of U.S. boosters used to loft payloads into Low Earth Orbit (LEO) meant that the first American satellites were diminutive compared to the early Russian Sputniks (“Traveling Companions”) of the day. Despite their small size, however, those early Explorer and Vanguard-series satellites made some of the most important early discoveries about the nature of the near-Earth environment, including finding the Van Allen Radiation Belts. However, when larger American boosters became available in the 1960s, the need to keep the weight and volume of satellite payloads began to take second place to increased functionality. Satellites became bigger, especially those associated with military space and intelligence roles and missions. This has culminated in intelligence payloads reportedly the size of school buses, requiring a Space Transportation System (STS – space shuttle) or high-end Evolved Expendable Launch Vehicle (EELV – Delta 4/Atlas 5) launch to lift them into orbit, resulting in high-risk multi-billion dollar missions/payloads that can take up to a decade to get into LEO.
With the reality of looming fiscal cuts on the horizon, a number of efforts to reduce the costs of satellites and boosters are ongoing within the U.S. military and intelligence communities. One of the most interesting and promising of these is the nanosatellite program being run by the U.S. Army’s Space and Missile Defense Command/Army Forces Strategic Command (SMDC/ARSTRAT) at the Redstone Arsenal in Huntsville, Ala. The SMDC-ONE nanosatellite is just what it sounds like: a small, 10 inch/25.4 centimeter long payload about the size of a small loaf of bread, lightweight (10 pound/4.5 kilogram) short lifetime (35 days on its first mission) LEO payload that amazingly, is designed to only cost between $300,000 and $400,000. The first SMDC-ONE nanosatellite was launched Dec. 8, 2010 on a SpaceX Falcon 9 rocket as a “piggyback” payload to their Dragon spacecraft prototype. Interestingly, SMDC-ONE was the first U.S. Army satellite launched in over 50 years, the first of eight such prototypes scheduled to be flown.
Once SMDC-ONE separated from the Falcon 9/Dragon stack, it began its designed mission of overflying the SMDC/ARSTRAT headquarters building, and began uploading the data recorded by an untended ground-based network of sensors monitoring the parking lot outside the Von Braun Laboratory in Huntsville. The network included three sets of seismic motion and passive infrared sensors, which were seeded in concealed positions, feeding into a small ground station. Even in its relatively low orbit (200 miles altitude), SMDC-ONE had a horizon footprint with a 1,200 mile/1,970 kilometer radius, allowing it line-of-sight to another small ground station located at the SMDC/ARSTRAT Battle Lab in Colorado Springs, Colo. Then, 12 to 15 times a day, SMDC-ONE would overfly the ground stations (with line-of-sight windows of roughly 5 minutes per site), upload the packetized image/text data from the Von Braun Lab parking lot sensor net, and download it to the terminal at the SMDC-ONE Battle Lab. A secondary objective of the SMDC-ONE mission was the relay of real time voice and text message data relay between tactical radio systems.
SMDC-ONE continued on its mission until January 12, when a power failure terminated its onboard functions. The next day its orbit decayed, and SMDC-ONE burned up in the atmosphere. But despite the short duration of SMDC-ONE’s mission, it is widely considered to be a completely successful evolution, which accomplished more than had ever been expected at launch. The impressive success of SMDC-ONE has SMDC/ARSTRAT readying additional nanosatellites for launch, four of which will reportedly be orbited in 2012. With the basic concept of nanosatellites now validated, SMDC/ARSTRAT are actively pursuing other roles and missions for these cheap, simple, and highly effective little birds.
At the same time, SMDC/ARSTRAT is also pursuing the other aspect of getting nanosatellites into orbit: launch options. While SMDC-ONE was able to get a ride on an adapter shroud of the SpaceX Falcon 9/Dragon stack, they want to be able to make launching and replenishment of nanosatellite constellations independent of tradition LEO launch services. To this end, SMDC/AFSC is developing the Multipurpose NanoMissile System (MNMS), based upon hardware from the well-proven ATACMS/MLRS family of rocket artillery. Able to be stacked and put on a launcher in less than 24 hours and costing under $1 million a launch, NanoMissile is planned to carry up to 22 pounds/10 kilograms into LEO. This would allow regional military commanders to launch or augment their own nanosatellite constellations at will, providing assured space-based services at their discretion.