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Dankanich J.W.,Gray Research Inc. | McAdams J.,Johns Hopkins University
Advances in the Astronautical Sciences | Year: 2011

NASA's Planetary Science Decadal Survey Committee was tasked to develop a comprehensive science and mission strategy that updates and extends the National Academies Space Studies Board's current solar system exploration decadal survey. A study for a Jupiter Trojan asteroid tour and rendezvous was led by the John's Hopkins University Applied Physics Laboratory. Mission concepts evaluated included ballistic chemical propulsion options and radioisotope electric propulsion options. The trajectory trades for the Jupiter Trojan rendezvous are presented herein.

Dankanich J.W.,Gray Research Inc. | Dankanich J.W.,NASA | Vondra B.,Ad Astra Rocket Company | Ilin A.V.,Ad Astra Rocket Company
46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit | Year: 2010

The use of electric propulsion for Mars has been explored since the 1970's when men looked to travel beyond the moon. The use of electric propulsion has been recommended in several studies as a low-risk, lower cost approach to the robotic Mars sample return missions. Electric propulsion has been evaluated for delivery of Mars cargo using power systems order of magnitude beyond state-of-the-art. Electric propulsion has also been considered for fast transits to Mars supporting manned exploration activities. Results of generalized electric propulsion transits form Earth to Mars are presented. Trades are presented as a generalized assessment based on spacecraft mass-to-power ratio, trip time, and propulsion system performance including variable and constant specific impulse, and efficiency. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

Dankanich J.W.,Gray Research Inc. | Dankanich J.W.,NASA
46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit | Year: 2010

The planetary science of small bodies includes missions for fly-by, rendezvous, and return samples from a diverse set of targets. Asteroids, comets, and deep space objects are found throughout the solar system over a wide range of heliocentric distances, inclinations, and eccentricities. The great diversity of targets and negligible gravity wells limits the use of chemical propulsion to the vast majority of targets. Electric propulsion enables the scientific exploration of several small body targets. The results of studies of small body missions enabled by electric propulsion are presented. Missions are evaluated for feasibility, performance, and propulsion and power system requirements. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

Smitherman D.,NASA | Griffin B.N.,Gray Research Inc. | Griffin B.N.,Jacobs Engineering
AIAA SPACE 2014 Conference and Exposition | Year: 2014

Future missions under consideration requiring human habitation beyond the International Space Station (ISS) include deep space habitats in the lunar vicinity to support asteroid retrieval missions, human and robotic lunar missions, satellite servicing, and Mars vehicle servicing missions. Habitat designs are also under consideration for missions beyond the Earth-Moon system, including transfers to near-Earth asteroids and Mars orbital destinations. A variety of habitat layouts have been considered, including those derived from the existing ISS designs and those that could be fabricated from the Space Launch System (SLS) propellant tanks. This paper presents a comparison showing several options for asteroid, lunar, and Mars mission habitats using ISS derived and SLS derived modules and identifies some of the advantages and disadvantages inherent in each. Key findings indicate that the larger SLS diameter modules offer built-in compatibility with the launch vehicle, single launch capability without on-orbit assembly, improved radiation protection, lighter structures per unit volume, and sufficient volume to accommodate consumables for long duration missions without resupply. The information provided with the findings includes mass and volume comparison data that should be helpful to future exploration mission planning efforts.

Dankanich J.W.,Gray Research Inc. | Patterson M.J.,NASA
47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2011 | Year: 2011

Electric propulsion thrusters with specific impulses from 1000s to 4000s are of interest for various mission applications. Mass constrained missions desire higher specific impulses, while time constrained GEO missions will optimize towards lower specific impulse and a higher thrust-to-power ratio. In the range of 1000 - 4000s specific impulse, thrusters are typically Hall thrusters for the higher thrust-to-power and gridded-ion engines for higher specific impulse. Mission flexibility can be increased by a thruster with a range of operability while maintaining high efficiency. A Dual-Mode Hybrid engine can provide mission flexibility with a single device providing either shorter transfer times or higher delivered mass without system complexities of multiple thruster systems. Dual-Mode Hybrid engine mission performance capabilities are presented herein. © 2011 by the American Institute of Aeronautics and Astronautics, Inc.

Griffin B.N.,Gray Research Inc.
Proceedings of the 12th International Conference on Engineering, Science, Construction, and Operations in Challenging Environments - Earth and Space 2010 | Year: 2010

With 1 rover, 2 astronauts and 3 days, the Apollo 17 Mission covered over 30 km, setup 10 scientific experiments and returned 110 kg of samples. This is a lot of science in a short time and the inspiration for a barebones, return-to-the-Moon strategy called Daylight Exploration. The Daylight Exploration approach poses an answer to the question, "What could the Apollo crew have done with more time and today's robotics?" In contrast to more ambitious and expensive strategies that create outposts then rely on pressurized rovers to drive to the science sites, Daylight Exploration is a low-overhead approach conceived to land near the scientific site, conduct Apollo-like exploration then leave before the sun goes down. A key motivation behind Daylight Exploration is cost reduction, but it does not come at the expense of scientific exploration. As a goal, Daylight Exploration provides access to the top 10 science sites by using the best capabilities of human and robotic exploration. Most science sites are within an equatorial band of 26 degrees latitude and on the Moon, at the equator, the day is 14 Earth days long; even more important, the lunar night is 14 days long. Human missions are constrained to 12 days because the energy storage systems required to operate during the lunar night adds mass, complexity and cost. In addition, short missions are beneficial because they require fewer consumables, do not require an airlock, reduce radiation exposure, minimize the dwell-time for the ascent and orbiting propulsion systems and allow a low-mass, campout accommodations. Key to Daylight Exploration is the use of piloted rovers used as tele-operated science platforms. Rovers are launched before or with the crew, and continue to operate between crew visits analyzing and collecting samples during the lunar daylight. © 2010 ASCE.

Dux I.J.,NASA | Huwaldt J.A.,SAIC | McKamey R.S.,SAIC | Dankanich J.W.,Gray Research Inc.
IEEE Aerospace Conference Proceedings | Year: 2011

The Mars ascent vehicle is a critical element of the robotic Mars sample return mission jointly planned by NASA and ESA. The Mars ascent vehicle must be developed to survive a variety of conditions including the trans-Mars journey, descent through the Martian atmosphere and the harsh Martian surface environments while maintaining the ability to deliver its payload to a low Mars orbit. The primary technology challenge of developing the Mars ascent vehicle system is designing for expected conditions while ensuring the mass limitations of the entry descent and landing system are not exceeded. The NASA In-Space Propulsion technology project has initiated the development of Mars ascent vehicle technologies with propulsion system performance and launch environments yet to be defined. To support the project's evaluation and development of various technology options the sensitivity of the Mars ascent vehicle gross liftoff mass to engine performance, inert mass, target orbits and launch conditions has been completed with the results presented herein. © 2011 IEEE.

Schmidt G.R.,NASA | Manzella D.H.,NASA | Kamhawi H.,NASA | Kremic T.,NASA | And 3 more authors.
Acta Astronautica | Year: 2010

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

Dankanich J.W.,Gray Research Inc. | Dankanich J.W.,NASA
46th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit | Year: 2010

The use of electric propulsion for near-Earth application has become routine and its capabilities continues to grow. However, there is limited experience with electric propulsion for planetary science missions. Low-thrust trajectory analysis is considered an art more than science with independent analyses producing inconsistent results. Planetary missions often have characteristics counterintuitive to standard ballistic trajectory design. A standard application of subsystem margins with the use of electric propulsion may not be appropriate due to margin associated interdependencies. An introduction to primary electric prolusion thrusters, mission design characteristics associated with low-thrust implementation and application are presented. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc.

Johnson L.,NASA | Whorton M.,NASA | Heaton A.,NASA | Pinson R.,NASA | And 2 more authors.
Acta Astronautica | Year: 2011

In the early to mid-2000s, NASA made substantial progress in the development of solar sail propulsion systems. Solar sail propulsion uses the solar radiation pressure exerted by the momentum transfer of reflected photons to generate a net force on a spacecraft. To date, solar sail propulsion systems were designed for large robotic spacecraft. Recently, however, NASA has been investigating the application of solar sails for small satellite propulsion. The NanoSail-D is a subscale solar sail system designed for possible small spacecraft applications. The NanoSail-D mission flew on board the ill-fated Falcon Rocket launched August 2, 2008, and due to the failure of that rocket, never achieved orbit. The NanoSail-D flight spare is ready for flight and a suitable launch arrangement is being actively pursued. This paper will present an introduction solar sail propulsion systems and an overview of the NanoSail-D spacecraft. © 2010 Elsevier Ltd. All rights reserved.

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