National Aeronautics and Space Administration
Small Business Innovation Research 2002 Program Solicitations

TOPIC H7 Space Transportation

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H7.01 High Power Electric Propulsion For Human Missions
H7.02 Unmanned Autonomous Rendezvous Systems
H7.03 Propulsion Systems Ground Test Operations

The goal of the HEDS Space Transportation topic is to identify and develop specific new space transportation technologies that can significantly increase the safety and reliability of ambitious future human exploration missions and campaigns beyond Earth orbit, while dramatically reducing the transportation-related cost of human exploration initial missions and sustained campaigns. This includes both systems and infrastructures associated with Earth-to-orbit transportation, in-space transport, and excursions from space to and from targets in space (including the Moon, Mars and asteroids). The objectives under this topic include 1) developing and demonstrating selected, highly innovative technologies needed to assure that future human exploration space transportation systems and infrastructures are safe and "robustly" reliable, 2) developing and validating technologies for the affordable transportation to - and from - targets in space beyond low Earth orbit, 3) enabling reliable and affordable transportation to all points of interest globally on the Moon or Mars, 4) establishing a foundation for profitable commercial development of space applications of these technologies in the mid- to far-term, 5) revolutionary propulsion systems and advanced space transfer technologies with application to mid- and far-term space exploration missions. Propulsion technologies that push the state-of-the-art in electric, electromagnetic, thermal and chemical systems, and 6) fission propulsion systems technologies that enable rapid and affordable in-space transportation, potentially leading to ambitious exploration of the solar system and beyond.

H7.01 High Power Electric Propulsion For Human Missions
Lead Center: GRC
Participating Center(s): JSC, MSFC

High-power (> 100 kW) electric propulsion technologies are a critical component of orbit transfer and planetary insertion in the HEDS missions. High-power electric propulsion can reduce propellant mass requirements (compared to all-chemical propulsion) to the extent that it allows a reduction in launch vehicle class or an increase in payload. In either case, the mass savings result in significant cost savings for HEDS missions. For interplanetary missions, high-power electric propulsion will provide quicker trips times (depending on available power) than all-chemical propulsion since its high specific impulse (Isp) allows for direct transit to planetary bodies.

Innovations in high-power electric propulsion technology are sought that will increase high-power electric thruster efficiency, increase thruster life, reduce total system mass, reduce system complexity, and reduce trip time. Thruster parameters of interest include power levels of 100-kW to several megawatts; Isp values of 2000 s for earth-orbit transfers to over 5000 s for planetary missions; thruster efficiencies in excess of 50%; and system lifetimes commensurate with mission requirements (typically 10,000 hours of operation). Proposals that seek to investigate and resolve, either theoretically or experimentally, the fundamental life-time and performance limiting mechanisms of high-power electric thrusters are of particular interest.

Several propulsion devices are being considered for high-power HEDS missions including Hall, Ion, mag-netoplasmadynamic (MPD) thrusters, pulsed inductive thrusters (PIT), and VASMIR. The specific technology challenges for high-power propulsion devices include:

Hall and Ion

• Scaled up in power (100 kW class)
• Use of alternate propellants such as krypton or argon
• Maintain high efficiency of today's lower power systems (>55 to 70% efficient)
• Long lifetimes (>10,000 hours)

MPD

• Long lifetime components >10,000 hours
• Improved efficiency (>60%)
• Simpler, higher efficient, continuous (not pulsed) power processing systems (>90%)
• Lighter thermal control (most of the inefficiency results in waste heat not removed by the exhaust, e.g. almost 400 kW of heat must be removed for a 1 MW MPD) (<2 kg/kWt)

  Pulsed Inductive Thrusters
  

• High efficiency >60%
• Simple, efficient and light pulsed power processing systems ( >90%, <1 kg/kW)

VASMIR

• High efficiency stages and processes (total efficiency >60%)
• Light components including superconducting magnets
• Advanced, long-term fuel storage (e.g. hydrogen and helium) [years on-orbit, <20% tankage]

Specific Impulse Throttling

• Techniques to allow for throttling of Isp at constant power (~2500 sec to 10,000 sec)
• Other innovative propulsion concepts providing the above Isp's, >60% efficiency, at power levels from 100 kW to multi-megawats

Support Systems

• Light, inexpensive, throttleable propellant feed systems for various fuels
• Radiation-resistant components to resist cosmic and power system radiation
• Safety and redundant systems to ensure crew member safety and mission success
• Gimbaling systems: (2DOF >+/- 20°)

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H7.02 Unmanned Autonomous Rendezvous Systems
Lead Center: MSFC

In support of future unmanned missions in Earth orbit, the need for an autonomous rendezvous and docking system has been identified as a critical enabling technology.

This subtopic addresses hardware and software technologies necessary to develop a robust autonomous guidance, navigation, and control (GN&C) capability to allow an unmanned autonomous rendezvous and docking of two vehicles in Earth orbit. This subtopic also addresses the technologies necessary to perform precision station keeping for capture and/or inspection of one vehicle by another vehicle. The primary objective is a low cost and highly robust system. The mission begins at launch vehicle main engine cutoff and includes autonomous orbit transfer, rendezvous, on-board mission planning and replanning, autonomous proximity operations and docking/capture.

Because of the absence of humans, the rendezvous and docking capability must be low risk with high robustness, ensuring a very high level of mission success. The proposed system should be modular and adaptable to wide range of missions and vehicles.

Specific innovations are sought to solve the following technology challenges:

• Spacecraft self determination of orbits. Innovative concepts may include ground tracking methodologies, land based or orbiting navigation and communication aids.
• Low Earth orbit, geostationary Earth orbit, and highly elliptical orbit rendezvous.
• Autonomous on-board mission planning and replanning algorithms and methodologies. Algorithms should include constraints inputs and optimization variability for mission time and propellant use.
• Relative navigation methods and sensors. A minimum relative navigation sensor suite addressing spacecraft-to-spacecraft ranges of 100 kilometers through docking, including relative attitude control during the final 100 meters of the approach.
• Light weight, low cost docking mechanisms which may include data, power, and fluid transfer capability.

Alternative strategies and supporting technologies are additionally sought.

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H7.03 Propulsion Systems Ground Test Operations
Lead Center: SSC

Proposals are solicited for innovative technologies applicable to ground testing of rocket engines. The goal is to reduce overall propulsion test operations costs (recurring costs) and/or increase reliability and performance of ground test facilities.

Specific areas of required technology innovation include the following:

• Improved cryogenic high-pressure/high-flow rate instrumentation. Temperature sensors that are exposed to the high pressure (up to 12,000 psi) and high flow rates (up to 2000 lb/sec, 333 ft/sec) required in cryogenic (down to 34R) rocket engine testing must be built with significant mass to survive the testing environment. Such robust sensors tend to have slower response rates. There is a need for temperature sensors with sub-millisecond response times that can withstand the afore-mentioned rocket engine testing environment.
• Improved low-cost cryogenic insulation. A requirement exists for more durable insulation materials for cryogenic (liquid oxygen and liquid hydrogen) tanks, pipes, and valves. This insulation must be resistant to deterioration in an environment of intense sunlight, high humidity, and frequent, heavy rainfall. It must also be resistant to detachment during thermal contraction and expansion cycles of the insulated components.
• New innovative approaches to incorporating knowledge and information processing techniques (prepositional logic, fuzzy logic, neural nets, etc.) to support test system decision making and operations. A requirement exists to develop, apply, and train intelligent agents, behavioral networks, and logic streams for rocket engine testing modes of operations and practice. Applications must operate statistically well on small and disparate data sources. The resulting products are inferential, representative, and they capture tacit and explicit knowledge. Statistic analysis must be supported.
• Model-based and knowledge-based methods to capture features from one dimensional sensor signals. The features of interest should help identify behaviors indicative of operating conditions (health) of sensors and the processes they monitor.
• Improved cryogenic propellant conditioning methods. New propulsion systems using cryogenic fueled rocket engines are designed with advanced propellant requirements, which includes propellant densification through sub-cooling. Improved methods are sought to meet these cryogenic propellant conditioning requirements for production and storage of densified propellants, such as sub cooled and slush hydrogen.
• Model development and validation of flare stacks, flare stack flame geometry, and flare stack atmospheric effects. When using hydrogen as a rocket engine propellant, hydrogen from boil-off, or hydrogen exhaust from testing components cannot be vented to the atmosphere. Flare stacks are used to burn off this excess hydrogen during both standby and testing operations. New techniques for modeling and designing flare stacks are needed to develop flare systems having improved operational ranges, reduced cost for supplemental purge gas usage, and low environmental impact. These flare systems must operate over a wide range of hydrogen flow rates, which span the range of a few cubic feet per minute to hundreds of pounds per second. Reduced interference with aircraft flying overhead is a desirable feature.

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