Rapid Response Flight Experiment

Engineers are using the RoadRunner satellite program to develop methodologies for rapid response space missions.

AFRL engineers are investigating ways to reduce the time it takes to design, build, test, and implement rapid response space missions to meet everchanging warfighter needs. Accordingly, the TacSat-2/RoadRunner Flight Experiment will address responsive spacecraft development; rapid launch vehicle integration; autonomous, onstation initiation; and enhanced subsystem and tactical payload operations.

Figure 1. The RoadRunner mission

The laboratory-led RoadRunner program stems from AFRL’s partnership with Air Force Space Command (AFSPC) and other Department of Defense organizations. The goal of this demonstration is to show the feasibility for the US Air Force (AF) to prepare a spacecraft (from inception to launch readiness) within 1 year; launch it from a stored state within 1 week of call-up; have it functioning autonomously in low earth orbit within 1 day after launch; and benefit from its subsequent performance of a militarily significant, 1-year mission (see Figure 1). AFSPC is providing the launch vehicle for a targeted Spring 2006 launch; however, the actual launch vehicle manifest will be influenced by Space Exploration Technologies Corporation’s timely completion of the low-cost Falcon I booster rocket.

Essentially, RoadRunner will demonstrate that the AF can develop and deploy critical space systems in much less time than ever before. The project’s new, more efficient development and deployment methods— called responsive space—will get spacecraft into orbit in a very short period of time. RoadRunner project success will also result in the adoption of existing on-orbit assets for new applications, using commercial capabilities for higher performance at a lower cost and initiating fresh methodologies yielding a shorter concept-to-results cycle.

Combat commanders must quickly respond to unanticipated military needs; their responses may include countering threats to space systems, enhancing capital assets, developing surge capabilities, investigating adversarial space systems, and supporting tactical forces. To address each of these potential responses, AFRL designed RoadRunner with a combination of payloads and mission segments for examining quick response, launch, and orbit initialization—the associated barriers, opportunities, novel approaches, and so on. To demonstrate responsive support to a tactical user, the spacecraft will receive a task from the ground and return requested mission data through a communications downlink in the same orbital pass. Additionally, Road- Runner will collect data that researchers will use in (1) characterizing a new sensing capability, (2) studying ways to ensure that mission development and launch timelines occur within 12 months of inception, and (3) exploring mature payloads with a new payload concept of operations. To achieve RoadRunner objectives, engineers leveraged AFRL’s TechSat-21 spacecraft design to house a combination of software and hardware payloads in a microsatellite-class spacecraft bus.

Figure 2. RoadRunner payloads that provide spacecraft subsystems and tactical mission capability

The RoadRunner team selected nine payloads to accomplish six primary mission scenarios: rapid development, rapid launch, autonomous on-orbit checkout, common data link (CDL) communications, imaging, and advanced technology. Currently, payload categories identify three levels of importance to the RoadRunner mission: Level 1 payloads address spacecraft subsystem requirements, Level 2 payloads meet the needs of the baseline tactical mission, and Level 3 payloads augment capability and enhance space research and development experiment payoff.

As depicted in Figure 2 (see next page), RoadRunner’s three Level 1 payloads— the Hall Effect Thruster (HET), Autonomy Software, and Integrated Global Positioning System On-Orbit Receiver (IGOR)—provide critical spacecraft functions. The HET payload is based on the Busek Company’s Tandem Hall Thruster. This next-generation ion engine, provided by AFRL propulsion engineers at Edwards Air Force Base (AFB), California, has variable specific impulse (up to 1600 s), variable thrust levels, and variable power usage. These flexible features make the system highly adaptable to changing mission requirements and future tactical satellite needs. The Autonomy Software payload has two major components: the On-Orbit Checkout Experiment (OOCE) and the Autonomous Tasking Experiment (ATE). Interface & Control Systems, Inc., is developing both experiments under AFRL direction. The OOCE is the enabling technology for autonomously commissioning the spacecraft during its first 24 hours on orbit, whereas the ATE software allows nonexpert users in the tactical battlefield to send data requests to the spacecraft and receive responses, ideally during the same satellite pass. Developed by Broad Reach Engineering and based on the National Aeronautics and Space Administration Jet Propulsion Laboratory’s BlackJack receiver design, RoadRunner’s third Level 1 payload, IGOR, facilitates ionospheric reflection and transmission experiments funded by the National Science Foundation (NSF). This payload also provides the spacecraft with the extremely precise navigation solution required for highprecision imaging operations.

Figure 2 also identifies RoadRunner’s Level 2 tactical payloads, the primary payload of which is a visible wavelength imager. AFRL is developing this device in conjunction with Science Applications International Corporation and Nova Biometrics to provide high-resolution imagery (distance resolution ~1 m) of objects on the ground. The US Army Space Program Office (ASPO) is responsible for the CDL payload, which is an experimental communication system designed for compatibility with CDL systems used in military unmanned air vehicles. The CDL payload will transmit data at >250 Mbits/s, fast enough to enable intheater commanders to request and receive images from RoadRunner during a single satellite pass. The third Level 2 payload is the RoadRunner On- Orbit Processing Experiment (ROPE), which employs an assembly of fieldprogrammable gate arrays to process and convert image data into standard military imaging formats to identify likely targets and compresses resulting data streams for instant access on the ground. AFRL scientists and engineers from Kirtland AFB, New Mexico, are responsible for developing ROPE.

Figure 3. RoadRunner payloads that deliver an augmented capability

The intent of RoadRunner’s Level 3 payloads is to test advanced capabilities (see Figure 3). AFRL scientists at Hanscom AFB, Massachusetts, are responsible for the Absolute Density Mass Spectrometer (ADMS) payload, which characterizes the neutral wind of the upper atmosphere. The Miniaturized Vibration Isolation System (MVIS) is an experimental component attachment system designed to actively damp spacecraft jitter; this system is particularly useful in improving the quality of images received from optical devices.1 Finally, AFRL scientists designed the Experimental Solar Array (ExpSA), a flexible thin-film photovoltaic array, to demonstrate two different cell technologies and two different deployment mechanisms. ExpSA offers the potential to reduce the storage volume needed for highpower microsatellite arrays and also reduces the mass and cost of the arrays.

RoadRunner’s success will complete the second critical step in a journey enabled by low-cost boosters and small spacecraft. Ultimately, AF commanders will be able to insert new warfighteroriented technology in 6 months or less and field a militarily significant payload in 1 day or less. AFRL scientists and engineers are developing and demonstrating associated methodologies to provide a foundation for subsequent experimentation intended to bring space to the battlefield in the 2010-2020 time frame.

Mr. James E. Winter and Mr. Pete D. Klupar, of the Air Force Research Laboratory’s Space Vehicles Directorate, wrote this article. For more information, contact TECH CONNECT at (800) 203-6451 or place a request at http://www.afrl.af.mil/techconn/index.htm. Reference document VS-04-08.

Reference 1

Hansen, E. and Hendersen, B. K. “A Miniaturized Vibration Isolation System for Laser Communications Components.” AFRL Technology Horizons®, vol 6, no 3 (Jun 05): 14-15.

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