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The Ultra Long Duration Balloon Project
Pergamon www.elsevier.nl/locate/asr
Adv. Space Res. Vol. 26, No. 9, pp. 1339-1343,2000 0 2000 COSPAR. Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0273-l 177KMJ$20.00 + 0.00 PII: SO273-1177(00)00119-8
THE ULTRA LONG DURATION BALLOON PROJECT IS. Smith Jr.
NASA Goddard Space Flight Center- Wallops Flight Facility
Wallops Island, VA 2333 7, USA
ABSTRACT The USA NASA Balloon Program research and development (R&D) efforts have focused on the development of technologies to support increased capability balloon missions. Advances made in analytical structural/performance modeling and lightweight composite materials offered the promise of superpressure balloons capable of extended flight duration. In 1997 a project was approved to develop and demonstrate a new capability to support balloon missions lasting up to 100 days above 33.5 kms. The development project, called the Ultra Long Duration Balloon Project (ULDB), will conclude with a demonstration flight in the year 2000. The ULDB Project consists of four major systems: Vehicle and Recovery, Ballooncratt, Mission and Operations, and the Science Instrument. Major challenges include the balloon material, balloon fabrication, power, cryogenic refrigeration, thermal control, attitude control, telecommunications and data storage, and international overflight. An overview of ULDB Project (Smith, 0 2000 COSPAR. Published by Elsevier Science Ltd. et al, 1998) will be presented BACKGROUND Advances by the Balloon Program research and development (R&D) activities in composite balloon materials and analytical tools, enabled NASA to consider development of an ULDB as an inexpensive altemative to place payloads into a near-space environment. A workshop was held in June 1996 to discuss the possibility of providing such a capability. This capability was targeted at providing roughly an order of magnitude increase in duration over the existing Long Duration Balloon (LDB) systems currently being flown from primarily Polar Regions. The scope of the development effort was to build upon the balloon philosophy and legacy in the identification, adaptation and implementation of relevant technologies found in the aeronautical, spacecraft and military environments for the development of a new science support capability to be demonstrated in the year 2000. In October 1997, a workshop was held at Goddard Space Flight Center (GSFC) concerning the prospects for such missions and identifying the scientific interest and preliminary science requirements for such systems and missions. Plans, schedules, cost estimates and management concepts were developed Efforts were initiated at GSFC/Wallops Flight Facility (WFF) for the management and development of the integrated, global ULDB system. A Technology Workshop was held at GSFC in June 1997 to identify new technologies and possible sources for the project. I339
1340
I. S. Smith, Jr.
Support for the development of ULDB has continued to grow since the first initial meeting held in June 1996. It is expected to be capable of supporting approximately 1000 kgs of scientific payload on a 600,000 m3 super pressure balloon for 100 days (-5 circumnavigations of the globe in either the northern or southern hemisphere). BALLOON VEHICLE & RECOVERY SYSTEMS The biggest technical challenge of the ULDB Project is the balloon vehicle. Small polyester film superpressure balloons have flown for up to several hundred days since the 1960’s. In the 1970’s attempts were made to scale these balloons up to larger volumes for heavier payloads and higher altitudes. Problems were identified with intrinsic properties of the polyester films, namely material defects and effectively zero tear strength, which would prevent scale up with any degree of reliability. Work was initiated by WFF starting in the earlier 1990’s to develop new materials to eliminate some of the problems with the polyester films. It was concluded that the best approach would be to develop a composite material, taking advantage of the good properties that different materials offered to offset deficiencies in the other components. With the initiation of the ULDB Project, trade studies and balloon designs have been performed. Prototype materials have been fabricated, tested in the laboratory and built into test structures and test balloons. Fabrication studies were initiated to evaluate various methods of seaming the materials for use in balloon structures. Development and production of the balloons are being supported by a multi-phase contract. This approach (Cathey 1998) establishes teaming partners, the materials, fabrication techniques, production equipment, procedures, quality control methods, and a mechanism for balloon procurement and risk mitigation. The first phase is to demonstrate a basic understanding and capability by manufacturing teams and wilI culminate with scaled hangar and flight test balloons in September 1998. A primary manufacturer will then be selected for the remaining phases to support the continued development of the balloon vehicle and material, development of new fabrication technology to lower production cost and increase reliability and produce flight test and the Demo 2000 flight balloons. The baseline balloon design is based on a modified spherical shape with an estimated volume between 450,000 and 600,000 m3, depending on the final material density. Load attachment is through hard end fittings. The balloon shell is ( or some slight derivative of) a composite material baaed on a polyester woven fabric, 6 micron polyester film and a 6 micron layer of polyethylene. The material strength is approximately 5,300 N/m and has an area1 density of between 50 to 70 g/m’. BALLOONCRAFI’ The Ballooncraft includes the power, electrical, telecommunications, command and data handling, sensors, attitude control, cryogenics, thermal and mechanical subsystems. The system is based largely on the experience gained from the LDB Program with additional redundancy and some new subsystems added. The power subsystem must be scalable, conformable to mission specifics and provide 1000 watts based on a 12-hour day/l2 hour night at 28V DC. The design is a pointed modular solar array, with NiMH battery power storage. The power distribution is modeled after the LDB power distribution unit with solid state switching. Pyrotechnics may include laser initiated ordnance due to increased static discharge
The Ultra Long Duration Balloon Project
1341
from the balloon and will make use of the NASA/Physical Sciences Laboratory Universal Terminate Package. Telecommunications will make use of TDRSS and will make use of a second generation Balloon-Class transceiver with a pointed TDRSS antenna to increase the downlink bit rate to 25Okbps. An Iridium housekeeping and backup system will be developed as part of the ULDB Project. The INMARSAT capability will be maintained in the event Iridium does not perform as expected. The ARGOS and line of site systems will also be maintained Data acquisition will be based on the LDB stacks for sensor and balloon apex plate acquisition. The Universal Termina te Package (UTP) will be used for terminate monitoring and control. A 1553B bus will be used to communicate with the science instrument with a fiber optic but through the balloon being considered, again due to possible increased balloon static charge build up. Data processing will be handled by a 486 class PC-104 bus single board computer, with PC-104 Quad serial cards and PC- 104 1553 interface cards. Data will also be stored onboard in hermetically sealed hard disks with 254 GB capacity. The ground station will be a PC platform running Window NT and using LabView for the monitor and control process and data display. Sensors will include GPS for position, velocity and timing, pressure transducers for pressure altitude, and other sensors such for housekeeping and monitoring of balloon performance and the flight enviromnent. Attitude control will be provided by an enhanced WFF/LDB rotator to provide improved accuracy and additional pointing modes. Cryogenics will be provided by a balloon flight qualified Sunpower Model M77 Stirling cycle cryocooler currently being evaluated and being flown on the Fairbanks ‘98 LDB flight Thermal will be provided primarily by passive techniques with application of next level of complexity methods, such as shutters, heaters, radiators, etc., as required. The Balloonc&/gondola fabrication will make use of conventional materials and fabrication techniques. MISSION & OPERATIONS The conducting of loo-day balloon missions is not trivial due to international overflight and the variability in the flight trajectories over the duration of the mission. The difficulties associated will not be addressed in this paper. Work has already been initiated with NASA Code I: International Affairs and the U.S. State Department to begin preparation for such missions. The mission and operations can he broken down into five phases: mission planning, integration and test, launch operations, flight monitoring and control and termination and recovery. Several studies have been initiated to further refine what can be expected during a loo-day mission and new mission planning tools are being developed Several studies are being performed in support of mission planning and operations. These include Southern Hemisphere wind studies, trajectory simulations to identify trajectory probabilities as well as launch site and launch date selection A Trajectory Simulation Tool and Workstation is being developed for mission planning and flight trajectory predictions which will be used for in-fIight monitoring and control. Storm probability and severity studies will be conducted in the ULDB Project to determine
1342
I. S. Smith,
Jr.
probabilities of severe storms and their impact on the mission. developed for the missions.
New atmospheric
models are being
The Demo 2000 mission will be launched in the Southern Hemisphere from Alice Springs, Australia or Christchurch, New Zealand depending on the science instrument. Integration and testing will be performed at WFF. Launch operations will be performed by NSBF personnel with the Operational Control Center located at the NSBF as it is currently. Flight monitoring and control will be supported by the current NSBF infrastructure with some augmentation by WFF Ballooncraft personnel for the Demo 2000 mission. Science will be able to access their data from their home institution via the Internet with science commanding via the Internet through the OCC for checking and validation. An onboard GPS dropsonde is being developed to aid in termination and descent trajectory predictions. Location aids will also be employed. Flight termination and recovery will occur over dry land and is currently planned for Australia or Brazil. Flight termination will be controlled by the OCC or in the field SCIENCE INSTRUMENT One of the requirements of the ULDB Demonstration Flight in the year 2000 (Demo 2000) was to accomplish meaningful science. Although this would sound like a natural requirement, implementation is not that easily accomplished. Current LDB missions lasting up to 22 days in the polar regions have demonstrated repeatedly that it has been very difficult for the science instruments flown on conventional balloons to make the transition to longer duration missions and have, in a large majority of the cases, resulted in instrument failure and problems just a few days into the mission. There may be some reasons for this occurring such as low funding levels. There is also an underlying feeling within the science community, stemming from the conventional program, that if something goes wrong the flight can be terminated, the payload recovered, refurbished and flown again This philosophy will not work for ULDB missions due to complexity and program costs. An integrated approach, similar to spacecraft is being implemented for ULDB missions. NASA Headquarters (HQ) for the Demo 2000 mission identified six (6) science instrument candidates. These included two cosmic ray, two-gamma ray and two infrared payloads. A primary and backup instrument was selected in February 1998 based on risk level, instrument maturity, demonstrated performance and redundancy of sub-systems for the Demo 2000 mission. The primary instrument, the Trans-Iron Galactic Element Recorder (TIGER) of Drs. Binns and Hink of Washington University, is a cosmic ray instrument for measuring the abundance of all elements with 2612540. The instrument is large enough to obtain good science with a loo-day flight from a latitude of 130 degrees. The instrument will have four scintillation counters for dlYdx measurements, two Cherenkov counters with radiators of different refractive index for velocity measurements, and scintillating fibers as a hodoscope. The overall dimensions of the detector, baaed on the ISOMAX balloon instrument, are 1.15 meters square by 0.6 meters deep and will be contained within a 3m kevlar pressure vessel. ACKNOWLEDGEMENTS The author we like to express his appreciation to the members of the ULDB IMT for their support and hard work. They are Msrs. David Stuchlik-Ballooncraft Manager and ULDB Systems Engineer, Henry Cathey-Balloon Vehicle and Recovery Systems Manager, David Gregory-Mission and Operations
The Ultra Long Duration Balloon Project
1343
Manager, Dr. Paul Hink-TIGER Co-1 and Instrument Manager and Dr. Michael Pelling-HIREGS Co-1 and Instrument Manager.
Cathey, H.M., Development of the NASA Long Duration Balloon Vehicle, 3Td COSPAR Scientz$c Assembly-Advances in Space Research, PSB l-0009, Nagoya, Japan, July 1998. Smith, I. S., D. Stuchlik, H. Cathey, D. Gregory, P. Hink, ULDB Systems Definition Review, Wallops Flight Facility, March 1998.
Adv. Space Res. Vol. 26, No. 9, pp. 1339-1343,2000 0 2000 COSPAR. Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0273-l 177KMJ$20.00 + 0.00 PII: SO273-1177(00)00119-8
THE ULTRA LONG DURATION BALLOON PROJECT IS. Smith Jr.
NASA Goddard Space Flight Center- Wallops Flight Facility
Wallops Island, VA 2333 7, USA
ABSTRACT The USA NASA Balloon Program research and development (R&D) efforts have focused on the development of technologies to support increased capability balloon missions. Advances made in analytical structural/performance modeling and lightweight composite materials offered the promise of superpressure balloons capable of extended flight duration. In 1997 a project was approved to develop and demonstrate a new capability to support balloon missions lasting up to 100 days above 33.5 kms. The development project, called the Ultra Long Duration Balloon Project (ULDB), will conclude with a demonstration flight in the year 2000. The ULDB Project consists of four major systems: Vehicle and Recovery, Ballooncratt, Mission and Operations, and the Science Instrument. Major challenges include the balloon material, balloon fabrication, power, cryogenic refrigeration, thermal control, attitude control, telecommunications and data storage, and international overflight. An overview of ULDB Project (Smith, 0 2000 COSPAR. Published by Elsevier Science Ltd. et al, 1998) will be presented BACKGROUND Advances by the Balloon Program research and development (R&D) activities in composite balloon materials and analytical tools, enabled NASA to consider development of an ULDB as an inexpensive altemative to place payloads into a near-space environment. A workshop was held in June 1996 to discuss the possibility of providing such a capability. This capability was targeted at providing roughly an order of magnitude increase in duration over the existing Long Duration Balloon (LDB) systems currently being flown from primarily Polar Regions. The scope of the development effort was to build upon the balloon philosophy and legacy in the identification, adaptation and implementation of relevant technologies found in the aeronautical, spacecraft and military environments for the development of a new science support capability to be demonstrated in the year 2000. In October 1997, a workshop was held at Goddard Space Flight Center (GSFC) concerning the prospects for such missions and identifying the scientific interest and preliminary science requirements for such systems and missions. Plans, schedules, cost estimates and management concepts were developed Efforts were initiated at GSFC/Wallops Flight Facility (WFF) for the management and development of the integrated, global ULDB system. A Technology Workshop was held at GSFC in June 1997 to identify new technologies and possible sources for the project. I339
1340
I. S. Smith, Jr.
Support for the development of ULDB has continued to grow since the first initial meeting held in June 1996. It is expected to be capable of supporting approximately 1000 kgs of scientific payload on a 600,000 m3 super pressure balloon for 100 days (-5 circumnavigations of the globe in either the northern or southern hemisphere). BALLOON VEHICLE & RECOVERY SYSTEMS The biggest technical challenge of the ULDB Project is the balloon vehicle. Small polyester film superpressure balloons have flown for up to several hundred days since the 1960’s. In the 1970’s attempts were made to scale these balloons up to larger volumes for heavier payloads and higher altitudes. Problems were identified with intrinsic properties of the polyester films, namely material defects and effectively zero tear strength, which would prevent scale up with any degree of reliability. Work was initiated by WFF starting in the earlier 1990’s to develop new materials to eliminate some of the problems with the polyester films. It was concluded that the best approach would be to develop a composite material, taking advantage of the good properties that different materials offered to offset deficiencies in the other components. With the initiation of the ULDB Project, trade studies and balloon designs have been performed. Prototype materials have been fabricated, tested in the laboratory and built into test structures and test balloons. Fabrication studies were initiated to evaluate various methods of seaming the materials for use in balloon structures. Development and production of the balloons are being supported by a multi-phase contract. This approach (Cathey 1998) establishes teaming partners, the materials, fabrication techniques, production equipment, procedures, quality control methods, and a mechanism for balloon procurement and risk mitigation. The first phase is to demonstrate a basic understanding and capability by manufacturing teams and wilI culminate with scaled hangar and flight test balloons in September 1998. A primary manufacturer will then be selected for the remaining phases to support the continued development of the balloon vehicle and material, development of new fabrication technology to lower production cost and increase reliability and produce flight test and the Demo 2000 flight balloons. The baseline balloon design is based on a modified spherical shape with an estimated volume between 450,000 and 600,000 m3, depending on the final material density. Load attachment is through hard end fittings. The balloon shell is ( or some slight derivative of) a composite material baaed on a polyester woven fabric, 6 micron polyester film and a 6 micron layer of polyethylene. The material strength is approximately 5,300 N/m and has an area1 density of between 50 to 70 g/m’. BALLOONCRAFI’ The Ballooncraft includes the power, electrical, telecommunications, command and data handling, sensors, attitude control, cryogenics, thermal and mechanical subsystems. The system is based largely on the experience gained from the LDB Program with additional redundancy and some new subsystems added. The power subsystem must be scalable, conformable to mission specifics and provide 1000 watts based on a 12-hour day/l2 hour night at 28V DC. The design is a pointed modular solar array, with NiMH battery power storage. The power distribution is modeled after the LDB power distribution unit with solid state switching. Pyrotechnics may include laser initiated ordnance due to increased static discharge
The Ultra Long Duration Balloon Project
1341
from the balloon and will make use of the NASA/Physical Sciences Laboratory Universal Terminate Package. Telecommunications will make use of TDRSS and will make use of a second generation Balloon-Class transceiver with a pointed TDRSS antenna to increase the downlink bit rate to 25Okbps. An Iridium housekeeping and backup system will be developed as part of the ULDB Project. The INMARSAT capability will be maintained in the event Iridium does not perform as expected. The ARGOS and line of site systems will also be maintained Data acquisition will be based on the LDB stacks for sensor and balloon apex plate acquisition. The Universal Termina te Package (UTP) will be used for terminate monitoring and control. A 1553B bus will be used to communicate with the science instrument with a fiber optic but through the balloon being considered, again due to possible increased balloon static charge build up. Data processing will be handled by a 486 class PC-104 bus single board computer, with PC-104 Quad serial cards and PC- 104 1553 interface cards. Data will also be stored onboard in hermetically sealed hard disks with 254 GB capacity. The ground station will be a PC platform running Window NT and using LabView for the monitor and control process and data display. Sensors will include GPS for position, velocity and timing, pressure transducers for pressure altitude, and other sensors such for housekeeping and monitoring of balloon performance and the flight enviromnent. Attitude control will be provided by an enhanced WFF/LDB rotator to provide improved accuracy and additional pointing modes. Cryogenics will be provided by a balloon flight qualified Sunpower Model M77 Stirling cycle cryocooler currently being evaluated and being flown on the Fairbanks ‘98 LDB flight Thermal will be provided primarily by passive techniques with application of next level of complexity methods, such as shutters, heaters, radiators, etc., as required. The Balloonc&/gondola fabrication will make use of conventional materials and fabrication techniques. MISSION & OPERATIONS The conducting of loo-day balloon missions is not trivial due to international overflight and the variability in the flight trajectories over the duration of the mission. The difficulties associated will not be addressed in this paper. Work has already been initiated with NASA Code I: International Affairs and the U.S. State Department to begin preparation for such missions. The mission and operations can he broken down into five phases: mission planning, integration and test, launch operations, flight monitoring and control and termination and recovery. Several studies have been initiated to further refine what can be expected during a loo-day mission and new mission planning tools are being developed Several studies are being performed in support of mission planning and operations. These include Southern Hemisphere wind studies, trajectory simulations to identify trajectory probabilities as well as launch site and launch date selection A Trajectory Simulation Tool and Workstation is being developed for mission planning and flight trajectory predictions which will be used for in-fIight monitoring and control. Storm probability and severity studies will be conducted in the ULDB Project to determine
1342
I. S. Smith,
Jr.
probabilities of severe storms and their impact on the mission. developed for the missions.
New atmospheric
models are being
The Demo 2000 mission will be launched in the Southern Hemisphere from Alice Springs, Australia or Christchurch, New Zealand depending on the science instrument. Integration and testing will be performed at WFF. Launch operations will be performed by NSBF personnel with the Operational Control Center located at the NSBF as it is currently. Flight monitoring and control will be supported by the current NSBF infrastructure with some augmentation by WFF Ballooncraft personnel for the Demo 2000 mission. Science will be able to access their data from their home institution via the Internet with science commanding via the Internet through the OCC for checking and validation. An onboard GPS dropsonde is being developed to aid in termination and descent trajectory predictions. Location aids will also be employed. Flight termination and recovery will occur over dry land and is currently planned for Australia or Brazil. Flight termination will be controlled by the OCC or in the field SCIENCE INSTRUMENT One of the requirements of the ULDB Demonstration Flight in the year 2000 (Demo 2000) was to accomplish meaningful science. Although this would sound like a natural requirement, implementation is not that easily accomplished. Current LDB missions lasting up to 22 days in the polar regions have demonstrated repeatedly that it has been very difficult for the science instruments flown on conventional balloons to make the transition to longer duration missions and have, in a large majority of the cases, resulted in instrument failure and problems just a few days into the mission. There may be some reasons for this occurring such as low funding levels. There is also an underlying feeling within the science community, stemming from the conventional program, that if something goes wrong the flight can be terminated, the payload recovered, refurbished and flown again This philosophy will not work for ULDB missions due to complexity and program costs. An integrated approach, similar to spacecraft is being implemented for ULDB missions. NASA Headquarters (HQ) for the Demo 2000 mission identified six (6) science instrument candidates. These included two cosmic ray, two-gamma ray and two infrared payloads. A primary and backup instrument was selected in February 1998 based on risk level, instrument maturity, demonstrated performance and redundancy of sub-systems for the Demo 2000 mission. The primary instrument, the Trans-Iron Galactic Element Recorder (TIGER) of Drs. Binns and Hink of Washington University, is a cosmic ray instrument for measuring the abundance of all elements with 2612540. The instrument is large enough to obtain good science with a loo-day flight from a latitude of 130 degrees. The instrument will have four scintillation counters for dlYdx measurements, two Cherenkov counters with radiators of different refractive index for velocity measurements, and scintillating fibers as a hodoscope. The overall dimensions of the detector, baaed on the ISOMAX balloon instrument, are 1.15 meters square by 0.6 meters deep and will be contained within a 3m kevlar pressure vessel. ACKNOWLEDGEMENTS The author we like to express his appreciation to the members of the ULDB IMT for their support and hard work. They are Msrs. David Stuchlik-Ballooncraft Manager and ULDB Systems Engineer, Henry Cathey-Balloon Vehicle and Recovery Systems Manager, David Gregory-Mission and Operations
The Ultra Long Duration Balloon Project
1343
Manager, Dr. Paul Hink-TIGER Co-1 and Instrument Manager and Dr. Michael Pelling-HIREGS Co-1 and Instrument Manager.
Cathey, H.M., Development of the NASA Long Duration Balloon Vehicle, 3Td COSPAR Scientz$c Assembly-Advances in Space Research, PSB l-0009, Nagoya, Japan, July 1998. Smith, I. S., D. Stuchlik, H. Cathey, D. Gregory, P. Hink, ULDB Systems Definition Review, Wallops Flight Facility, March 1998.