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Archive: GDIN Pilot Project
Stratospheric Satellites

Concept:

Global Aerospace Corporation (GAC) developed a revolutionary concept for a global network of perhaps hundreds of low-cost autonomous stratospheric satellite (StratoSat™) systems, to address GDINs goal of providing disaster information in time to make the right decisions by globally observing the Earth's surface and detecting and monitoring environmental hazards. StratoSat™ systems are uninhabited balloon platforms that float in stratospheric winds and collect data. The StratoSat™ systems utilize a small amount of trajectory control to meet observation objectives.

Problems:

  • Current observing systems (like satellites and aircraft) are expensive.
  • Satellites cannot be positioned over the target disaster area.
  • Multiple crewed aircraft are unpractical for providing continuous global monitoring due to expense, safety, and pollution.
  • Higher resolution than space-based data may be required for successful disaster management.

Capabilities and Characteristics:

The key capabilities of a network of StratoSat™ systems that would make it useful to GDIN are:

  • High Spatial Resolution Imagery and Data – Drifting at the height of 35 km, StratoSat™ platforms will provide imagery, remote sensing and in-situ data of higher resolution and quality than can be provided by a satellite.
  • Low Cost – Due to the advance of electronics, communications, and balloon technologies, the cost of each StratoSat™ platform is expected to be at the level that would make it feasible to deploy hundreds of platforms for global coverage at a fraction of a cost of a satellite launch. A small balloon is proposed to keep costs low and improve safety margins.
  • Long Duration – StratoSat™ platforms are expected to operate for up to 3 to 10 years after launch at the "edge of space," 35 km altitude. No consumables are required for maintaining flight for flights of up to 3 years in duration. The power for payload operation will be provided by solar panels.
  • Large Payload – The full-scale StratoSat™ platform will support a payload of 100 kg or more. Heavier payloads (2 to 3 tons) are possible for increased balloon costs. A potential payload may include high-resolution imagery and a set of instruments for remote and in-situ sensing relevant to hazard detection and disaster monitoring.
  • Trajectory Control – An innovative balloon trajectory control system (TCS) maneuvers the StratoSat™ platform over a disaster site. Algorithms based on the studies of natural grouping behavior (flocks of birds and schools of fish) are currently being develop that would allow for "intelligent" group behavior of the members of the network.
  • Mobility – StratoSat™ platforms will be "always there" and provide global coverage of the Earth surface. Small adjustments to the trajectories would allow positioning of the closest StratoSat™ platforms over the disaster site in a matter of hours. Continuous overflight of the target region can also be achieved: after one StratoSat™ system moves over the horizon, another enters the scene to take its place and resume observations.
  • Global Communication – StratoSat™ platforms can be positioned to be constantly in view of each other to relay data from the disaster-affected area to a coordination center many kilometers away or to provide a regional communication network.

Operational Scheme

The global constellation and network of tens to hundreds StratoSat™ platforms will constantly monitor the Earth surface and atmosphere and provide a wealth of information for disaster management and, possibly, disaster forecast. The information will be relayed from StratoSat™ platforms to ground stations and disseminated to member nations. Ground stations also maintain desired constellation geometry and direct StratoSat™ platforms towards a disaster site. StratoSat™ platforms will be the fastest and cheapest means of reconnaissance and communication over a disaster area.

Technologies:

The StratoSat™ platform concept is based on several relevant technologies:

  • ULDB – NASA Ultra Long Duration Balloon (ULDB) Project is developing pumpkin-shaped superpressure balloon technology capable of carrying a 2045 kg payload to a 34 km float altitudes. At the successful June 2000 test, the scaled version of the ULDB reached height of 28 km and carried a payload of 777 kg.

    Figure 1 Successful ULDB test, June 2000 (courtesy of NASA).
  • StratoSail® TCS — The StratoSail® balloon trajectory control system (TCS) is designed to alter the flight path of balloons. The StratoSail® TCS takes advantage of the natural difference in wind speed and direction at different altitudes in the atmosphere. A wing is suspended several kilometers below the balloon gondola using a long thin tether. The wing hangs on end, so its "lift" acts sideways rather than upward as in an airplane. This sideways lift force is used to drag the balloon across the relative wind. This allows the balloon to be maneuvered towards regions of interest.

    Figure 2 Artist rendition of StratoSail® TCS in flight

  • Advanced payload termination systems IST Aerospace developed the ORION™ Navigation Guidance and Control System (NGCS) for NASA and the French space agency’s (CNES) balloon program. The ORION™ system is a version of the Guided Parafoil Airborne Delivery System (GPADS), being developed for the US Department of Defense. It is used to autonomously fly the parafoil to a landing site loaded into the guidance software, turn into the wind, and flare, thus providing a slow speed, low impact landing on land. The French ORION™ system is capable of delivering 350-700-kg payloads to within 100 m of a pre-designated target. The ORION™ system could deliver the StratoSat™ platform payload to a safe landing after termination of the flight. To date NASA and the CNES have carried out several flight tests of the ORION™ system.


    Figure 3 The ORION™ NGCS Guiding the X-38 to a Safe Landing.

 

For further information on StratoSat™ platforms, please contact GDIN Secretariat or  Global Aerospace Corporation. Global Aerospace Corporation is supported by NASA and the NASA Institute for Advanced Concepts in developing this technology.

Related Links:

Global Networks of Stratospheric Platforms

StratoSail® TCS

NASA Ultra-Long Duration Balloon Project

ORION

NASA Institute for Advanced Concepts