The Autonomous Flight Termination Unit (AFTU) is an independent, self-contained subsystem mounted onboard a launch vehicle.
The AFTU autonomously makes flight termination/vehicle destruct decisions using configurable software-based rules implemented on redundant flight processors using data from redundant navigation sensors. The ability to perform this function on the launch vehicle results in tremendous cost savings by eliminating the need for ground personnel, transmitters, telemetry receivers, and radars historically used for this purpose. It also provides global coverage because launch vehicles using AFTU no longer need to be launched from a dedicated range. AFTU can also support multiple vehicles simultaneously, such as flyback boosters.
Funding, development, testing, and transfer of the AFTU has been a team effort involving four partners: Defense Advanced Research Projects Agency (DARPA), United States Air Force (USAF), National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA). The four partners in the AFTU transfer story each had a unique role in its success. DARPA, through its Airborne Launch Assist Space Access (ALASA) program, provided funding for AFTU research, development, and prototyping as well as providing launch opportunities aboard various launch vehicles for AFTU hardware and software testing. NASA Kennedy Space Center (KSC) and the Air Force combined their expertise to jointly develop the Core Autonomous Safety Software (CASS) that is flown on any launch vehicle utilizing the AFTU technology.
CASS is mission critical for any launch vehicle equipped with an AFTU because it contains the mission rules and parameters used by the AFTU to make flight termination/vehicle destruct decisions.
This cooperative joint effort was key to the development of CASS software that meets all safety critical requirements for operational use. DARPA funded the independent validation and verification testing of the CASS software required in order for CASS to be declared flight ready. NASA KSC was responsible for the development, prototyping, and testing of the AFTU hardware as well as the wrapper software that allows the CASS software to interface with the AFTU hardware. The USAF provided oversight on the AFTU hardware design and helped write, coordinate and approve NASA AFTU requirements for design, test and operation. The FAA provided oversight and approval of NASA AFTU requirements, design, test and operation of AFTU software and hardware for commercial space operational use.
The result of this four-way partnership is a generic engineering version of the AFTU hardware and wrapper software along with CASS software that can be used by the government or commercial space companies as a baseline for developing their own versions of an autonomous flight termination system
for their launch vehicles. This will help significantly shorten each company's development timeline and cost. The KSC Technology Transfer Office has to date completed 21 transfers of the AFTU technology to commercial space companies, one of which is working with the Army on possible adaptation of the AFTU for the Advanced Hypersonic Weapons Program.