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DARPA Releases "System F6" Program Details
The Defense Advanced Research Projects Agency (DARPA) released a Broad Agency Announcement (BAA) on Friday for the agency's System F6 program.

DARPA is soliciting innovative proposals for the performance of research, development, design, and testing to support the agency's System F6 concept. Also known as "Future Fast, Flexible, Fractionated, Free-Flying Spacecraft united by Information exchange".

The objective of the System F6 program is to demonstrate the feasibility and benefits of a satellite architecture wherein the functionality of a traditional “monolithic” spacecraft is replaced by a cluster of wirelessly interconnected spacecraft modules. Each such “fractionated” module can contribute a unique capability, e.g., command and data handling, guidance and navigation, payload, etc., or it replicates the capability of another module.

The fractionated modules can be physically connected once in orbit or remain nearby to each other in a loose formation, or cluster. Harnessed together through a wireless network they create a virtual satellite delivering capability, which is at least equivalent to the monolithic spacecraft. "Concurrently, they significantly enhance flexibility and robustness, and reduce risk through the mission life and spacecraft development cycle," DARPA said in the BAA.

Proposed research under the BAA should investigate innovative approaches that enable revolutionary advances in science, devices, or systems.

With a network of wirelessly connected modules, cluster navigation capability becomes a key concern. It is envisioned that separate modules could be launched independently. As such, there will be a need for these modules to gather, dock and/or virtually dock.

"If under attack, these modules must undock, disperse, and re-dock." DARPA said.

"The F6 network should have the qualities of the best war fighting networks of today," DARPA said, "specifically, it should be self-forming, reliable, have high availability, and be robust (and therefore self-healing)".

DARPA list the following advantages to the fractionated System F6 approach:

* Diversification of launch and on-orbit failure risk.
* Survivability enhancement from a variety of natural and manmade threats (e.g. antisatellite weapons).
* Reliability enhancement through emergent sharing of subsystem resources across
multiple stand-alone fractionated systems.
* Scalability in response to service demand fluctuations.
* Upgrade ability in response to technological obsolescence.
* Incremental deployment of capability to orbit.
* Graceful deterioration of capability on-orbit.
* Robustness in response to funding fluctuations and requirements changes.
* Reduced integration and testing due to subsystem decoupling.
* Decoupling of requirements between modules and multiple payloads.
* Decoupling of security constraints between payload(s) and rest of spacecraft.
* Production learning across multiple similar modules.
* Reliability learning across multiple similar modules.
* Enabling very large spacecraft beyond capability of the Evolved Expendable Launch
Vehicle.
* Enabling spacecraft to be launched with smaller, faster vehicles.
* Enabling development of smaller payload nodes decoupled from spacecraft.
* Reducing the economic barrier to entry for non-traditional spacecraft vendors.

System F6 program objectives:

* Each spacecraft module shall be on a smallsat/microsat scale (300 kilograms wet mass). Wet mass should include propellant required for insertion into the prescribed mission orbit from an assumed launch vehicle, a planned one-year of system lifetime operation after the scheduled launch of the final module, and propellant required for any orbital debris mitigation.
* First launch shall be planned to occur within four years of program start.
* Modules may be distributed across multiple launches.
* The launch vehicle(s) required shall be commercially available, manufactured in the US, and have demonstrated at least one successful previous launch.
* The on-orbit lifetime design of the system shall be at least one year after the launch of the final spacecraft. No P, requirements will be issued, but all designs should retain a fault tolerant strategy that limits the effects of single part failures on the ability to command each spacecraft, as well as to limit any navigational threats during cluster operations (e.g. a thruster inadvertently stuck open).

Posted by: Anonymoose 2007-07-28
http://www.rantburg.com/poparticle.php?ID=194742