High-Altitude Balloon Experiment (HABE)

The mission of the High-Altitude Balloon Experiment (HABE) is to acquire supporting data, validate enabling technologies, and resolve critical acquisition, tracking, and pointing (ATP) and fire control issues in support of future space-based precision pointing experiments. The use of high-altitude balloons offers a relatively low-cost, low-vibration test platform, a recoverable and reusable payload, worldwide launch capability, and a 'near- space' emulation of the future space systems operational scenarios. The HABE platform design is based on several previous spacecraft designs, and includes coarse gimbal pointing, infrared and visible passive tracking, active fine tracking, internal auto alignment and boresighting, and precision line-of-sight (LOS) stabilization functions.

The High Altitude Balloon Experiment demonstration of Acquisition, Tracking, and Pointing (HABE-ATP) is a system build around balloon-borne payload which is carried to a nominal 26-km altitude. The goal is laser tracking thrusting theater and strategic missiles, and then pointing a surrogate laser weapon beam, with performance levels and a timeline traceable to operational laser weapon system requirements. This goal leads to an experiment system design which combines hardware from many technology areas: an optical telescope and IR sensors; an advanced angular inertial reference; a flexible, multi-level of actuation digital control system; digital tracking processors which incorporate real-time image analysis and a pulsed, diode-pumped solid state tracking laser. The system components have been selected to meet the overall experiment goals of tracking unmodified boosters at 50-200 km.

The HABE system used a tandem balloon configuration which is characterized by gas confinement in a relatively small "tow balloon" at launch. Later, the payload section separates and drops 500 feet bellow the tow balloon which allows the deployment of the main balloon. For this mission, the tow balloon is approximately 70 ft diameter weighing 400 lbs. At liftoff, the balloon is filled with helium until the pull on the payload is nominally 12% higher than the weight of the payload and balloon. At 20knots wind, the expected side force on the tow balloon would be approximately 1,500 1bs.

Within a seven month period, Goodrich's Electro-Optical Systems designed, built, integrated, tested and delivered the 60 cm Phillips Laboratories balloon borne telescope. The telescope is the prime optical receiver for experiments to be conducted in target acquisition, tracking and pointing (ATP) for ballistic missile defense technology development. The telescope is designed to survive a 10g parachute landing and to refly a series of test flights with a minimum of maintenance. Flight altitude is 80,000 feet. It is a two-mirror Cassegrain design, operating in the 0.532 to 4.3 micron waveband with an FOV of 3.5 micro-radians. System performance (measured) is 0.073 ? RMS at 633 microns. The telescope operates over a range of +45 (from horizontal) to -30. System weight is 200 lb.

The 60-cm diameter telescope is the primary optical receiver in the payload that is used to track targets and acquire optical data. It is located on the gimballed optics bench along with the coarse acquisition camera and the ranger scorer. The telescope images the target on to the infrared (IR) intermediate-tracking and fine-tracking cameras and also images the marker laser beam onto the target. A l-1/2-in, diameteralignment laser beam also traverses the telescope and is used to reduce jitter between all optics commonto the incident fine-tracking wave front and the exiting marker laser beam. The transmitted wave front requirement is driven by the required size of the marker laser on the target.

The HABE telescope must operate in an adverse thermal environment that changes during the mission. Prior to launch, the telescope is sealed in the optics canister and the primary mirror is cooled to -35 C. As the balloon rises, the pressure is reduced in the canister,and when the flight altitude is reached,the canister is opened. The telescope has been designed and fabricated with materials chosen so that it operates similarly to an isothermal system with components that areheld in alignment over the temperature range from 20 to -55 C. To reduce any lateral temperature gradients on the metering structure that would cause misalignment,the metering structure is located between an inner light baffle and an outer radiation shield. Even with this design, there still may exist within the interiorof the telescope largetemperature gradients that can heat to a varyingdegree the residual air contained within the optical path. Although at 26 km the density of the air has dropped to 1.4 percent of the standard temperature and pressure(STP) value, there is sufficient density change along the optical path of 1.4m to distort the wavefront.

In October 1997 Phillips Laboratory announced a procurement of operational engineering and data analysis support for two additional flights of the High-Altitude Balloon Experiment (HABE) Payload. The proposed contract will encompass HABE payload refurbishment, repair, and upgrade from previous balloon flights, HABE payload flight operations, data analysis and reporting, and assist in HABE payload disposal as directed by the Government. The expected duration of the proposed contract is fourteen (14) months beginning in the first quarter of Fiscal Year 1999 and ending at the completion of the second flight data analysis and final report. The government expects to award a single cost plus award fee (CPAF)contract for approximately $5M. The level of classification for this effort is unclassified. The desired contractor will have experienced acquisition, tracking, and pointing engineers, laser engineers, controls engineers, electrical engineers, mechanical engineers, and software and simulation engineers with the capability to work using the C computer language in a Unix software development environment and in a Matlab simulation environment, as well as personnel experienced in balloon launch and recovery operations. For HABE payload refurbishment, repair, and upgrade, the contractor will be expected to prepare test plans and procedures, troubleshoot, repair, align, check out, and perform any other work necessary to repair and upgrade the HABE payload, verify the operational status of the HABE payload, and analyze and report on the results of the refurbishment and repair activity, including a detailed analysis of any failures encountered. For HABE payload flight operations, the contractor, in coordination withthe Government, will be expected to prepare checklists and procedures, execute flight rehearsals, prepare the HABE payload and mobile payload operations center for deployment, assist in HABE pre-launch checklist execution and launch, operate the HABE payload during the two HABE missions, and prepare the HABE payload and mobile payload operations center for return to Kirtland AFB NM. For data analysis and reporting, the contractor will be expected to completely analyze the collected data for the HABE mission, draw conclusions from the data, report on the data in a formal deliverable report. For HABE payload disposal assistance, the contractor will be expected to dismantle, catalogue, ship, and otherwise dispose of the components of the HABE payload and mobile payload operations center as directed by the Government, and document the disposition of each component.

In 1998, the Phillips-Laboratory-executed High Altitude Balloon Experiment, (HABE) will demonstrate autonomous end-to-end operation of the key ATP-Fire Control (FC) functions in a realistic timeline against actual thrusting ballistic missiles. HABE will use a visible low-power marker beam as a surrogate to the megawatt HF beam and measure beam pointing accuracy, jitter and drift against a fixed aimpoint on the target.

The Air Force Research Laboratory's High Altitude Balloon Experiment (HABE), a BMDO sponsored effort to demonstrate precision acquisition, tracking, and pointing, has been transferred from AFRL to the Space Based Laser's Joint Venture Team. Team SBL IFX, El Segundo, Calif., was awarded on June 29, 2000 a $10,157,979 modification to a cost-plus-award-fee contract to incorporate additional effort into the Space Based Laser (SBL) Integrated Flight Experiment (IFX) program and extend delivery of the Systems Readiness Review from Oct. 31, 2000 to Dec. 5, 2000. This additional effort includes functional testing of the Beam Profile Generator, high power testing of the Capistrano Test Sight, Beam Control element test support, and incorporation of the high Altitude Balloon Experiment into the IFX contract. Expected contract completion date is Dec. 31, 2000. Solicitation issue date was Feb. 25, 2000. Negotiation completion date was May 24, 2000. Space and Missile System Center, Los Angeles AFB, Calif., is the contracting activity (F04701-99-C-0026-P00017).

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