The current range ground-based infrastructure is extremely costly to operate and maintain. NASA has developed an Autonomous Flight Termination System (AFTS) that is an independent, self-contained subsystem mounted onboard a launch vehicle. The AFTS reference system eliminates the need for a ground-based infrastructure by moving the flight termination function from the ground to the launch vehicle. It will allow multiple vehicles to be launched and tracked at the same time. AFTS is necessary to support vehicles that have multiple flyback boosters.

The AFTS can augment or replace the functions of the traditional humanin- the-loop system. Redundant AFTS processors evaluate data from onboard Global Positioning System (GPS) and inertial measurement unit (IMU) navigation sensors. Configurable rulebased algorithms are used to make flight termination decisions. The mission rules are developed by the local Range Safety Authorities using the inventory of rule types taken from current human-in-the-loop operational flight safety practices. The main benefit of the AFTS is to decrease the need for permanent ground-based range safety assets with a corresponding savings in operational costs, and to increase the number of potential launch sites and corridors. The ultimate goal of this project is to produce an autonomous flight safety reference design that may be commercialized for industry use.

The system uses a commercial off-the-shelf (COTS) chassis, a NASA-designed custom board, NASA-developed wrapper interface software, and the Core Autonomous Safety Software (CASS) running on a COTS processor. The range requires that the AFTS system consist of redundant chassis with redundant sensor inputs. The sensor inputs can be GPS, INS, IMU, ac celerometers, or any combination thereof. All sensor inputs can be available to both chassis.

Each chassis is capable of initiating a flight termination. If both chassis are healthy, and either recommends a flight termination, the flight will be terminated. If one chassis is unhealthy, its failsafe must initiate a termination unless it can verify the other chassis is healthy. If both chassis are unhealthy, both failsafes will initiate a termination.

This work was done by Lisa Valencia, Robert Morrison, and Roger Zoerner of Kennedy Space Center. For more information, contact the Kennedy Space Center Technology Transfer Office at 321-867-5033. Refer to KSC-13978.


NASA Tech Briefs Magazine

This article first appeared in the March, 2016 issue of NASA Tech Briefs Magazine.

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