350 likes | 489 Views
Asteroid Wrangler-Contractor 4. Grant Atkinson Chris Drury Brian Fredericks. Anton Kolomiets Kim Liotta Daniel Seitz Marcus Payne. Mission Statement and Objective.
E N D
Asteroid Wrangler-Contractor 4 Grant Atkinson Chris Drury Brian Fredericks Anton Kolomiets Kim Liotta Daniel Seitz Marcus Payne
Mission Statement and Objective “To deliver a manned mission to a near-earth asteroid, conduct experiments critical to the human colonization and utilization of extra-planetary bodies, and ensure the safe return to earth of all mission data, equipment, and personnel.” • Explore possibility of space colonization • Mining and use of resources • Geology and scientific experimentation
Mission Profile (3) 30 day loiter at asteroid (4) Depart asteroid for Earth under sustained thrust (2) Accelerate to asteroid under sustained thrust (1) Depart low Earth orbit (LEO) under low thrust (5) Return to LEO under low thrust
An Initial Look at Asteroids The initial criteria for selecting asteroids: • Very close to earth in at least one pass • Must be large enough to land a craft • Prefer to have exotic compounds • Mineral rich or organic • Asteroid needs to be solid • Prefer around relative speed of 2 km/s
Asteroids not selected • These asteroids initially looked promising but due to their small size and mass it would be impractical to land on them. • 1991 VG • 2008 HU4 • 2008 EA9 • These asteroids were more promising due to size and close approaches. wallpapers-diq.com
Selected Asteroid:1998 KY26 • Diameter of 30 meters • Relative velocity of 3.14 km/s • A relatively small asteroid • Fast spinning: rotation period of 10.7 minutes • Likely solid mass rather than rubble pile • Believed to be a water-rich asteroid • Further scientific research • Potential water is important to future space colonization • Gives an insight to the distribution and history of water
Overall Configuration Propulsion Module Habitat Module Powerplant Module • Main Components: • Habitat Module • Propulsion Module • Powerplant Module
Propulsion and Power Configuration • Propulsion Module: • VASIMR- 2,500 kg • PowerplantModule • 1.64 MW Reactor - 4,900 kg • Radiator -3,600 kg • Other Systems • Radiation Shelter- 5,000 kg • Scientific Payload/Communications • - 10,000 kg • Life Support- 8,800 kg
Habitation Module Configuration • Similar in size and configuration to Bigelow Sundancer: • Total Spacecraft Mass - 35,800 kg
Propulsion Trade Tree Propulsion Subsystem Chemical Nuclear Thermal Electric LOX/LH2 LOX/LCH4 NTO/MMH LH2 NH3 Electrostatic Hall Effect VASIMR
Propulsion Selection • Chemical eliminated • Lowest isp • Highest initial mass in LEO • Nuclear thermal eliminated • isp better than chemical, but still too low • High initial mass in LEO • Political issues • Electric selected • Highest isp • VASIMR offers best isp and T/W ratio • Lowest initial mass in LEO
Power Subsystems Power subsystem Nuclear Solar photovoltaic Solar thermal • Nuclear primary • Lowest specific mass • 3 kg/kW achievable • 1.64 MW required for VASIMR (4,920 kg) • Liquid sodium coolant • Lowest mass • Highest reliability • Solar auxiliary • Large area required for VASIMR power levels • Flight heritage solar specific mass >10 kg/kW • Hab, communications power supplied by photovoltaics
Fuel and Thrust Estimates • Assumptions: • Total Dry mass: Approx. 35,800 kg • Isp: Approx. 5000 sec • Transit time about 100 days • Stay time of 30 days • Relative Asteroid Velocity of 3.14 km/s • Propellant Mass is approximately 13.6 MT • Thrust Required:
Launch System • Initial mass in LEO requires at least 2-3 EELV launches. • One HLLV launch reduces on orbit assembly if available. • At least one assembly/checkout mission before departure. • Crew transport by commercial vehicles.
Crew Demographics • Five crew • One commander • Two scientists • One field geologist • Two engineers • Key responsibility: Maintaining vehicle health • At least one crew with medical training
Psychological Aspects • Confined spaces are detrimental to human mental health, especially for extended periods of time. • 36m3 of living space was allotted for each person, which is double that required by NASA • Windows and careful design can make confined spaces less harmful
Rotation and Life Support Artificial Gravity • Rotation • Linear Acceleration • Mass • Magnetism • Tether Rotation • Rotation Parameters • 0.6 g selected • 3 rpm • Tether Mass: ~100 kg • Propulsion Module located at CM
Artificial Gravity 0.035 g Limit of low traction 1g Comfort zone 4 rpm Onset of motion sickness 6 m/s rim speed Apparent gravity depends on direction of motion
Life Support System • Excellent Protection • Micrometeoroid and radiation • Low mass for given volume • 180 m3 pressurized volume • 10,000 kg mass • All mass estimates for five crew, one year requirements: • Oxygen/CO2 removal: 1,850 kg • Food: 3,890 kg • Water (With 90% recycling): 3,080 kg • Mass total: 8,820 kg
Acute Radiation Shielding Subsystem • Advantages: Disadvantages: • Very high density: 19 g/cm3 • Currently costs about $200/kg • Not useful in blocking gamma radiation • Weakens in the presence of oxygen • Cannot block gamma radiation • Maintaining field strength at low temperatures has yet to be demonstrated • Highly effective in absorbing gamma rays • Low halving thickness: 0.2 cm (1/5 Lead) • Attenuates neutrons extremely well due to hydrogen rich make-up • Low density (0.941 g/cm3) and very cheap ($1.50/kg) • Mass saving • Little or no electrical power input required • Great at deflecting solar flare protons Depleted Uranium High Density Polyethylene Active Electromagnetic
Storm Shelter and Chronic Shielding • To protect the astronauts during a solar storm, the Habitation module will contain a storm shelter at its core. • The walls of this shelter will be lined with Depleted Uranium 0.04” thick, reducing radiation inside the shelter by 25% • Mass of shelter approximately 5,179 kg • Polymer rich walls (~16” thick) and deployable water jackets provide ample chronic radiation protection. Hab walls provide chronic radiation shielding Inner chamber is the storm shelter
Transportation to Asteroid • Tether between spacecraft and asteroid • Spacesuit maneuvering thrusters used for safety • Mass savings relative to free-flying vehicles • Cargo capability built into mining machinery • Free flying vehicles • More massive • More expensive to develop
Asteroid Mining Options • Drilling: Similar to oil exploration • Would require an anchor to counter the small gravity environment • Well-suited on Earth due to high gravity • Strip Mining: scraping away at the asteroid’s surface and a canopy collects debris that is kicked up. • Would require either anchors or cables around the asteroid. • Less massive than drilling.
Telecom Trade Tree Telecommunications Subsystem • Omnidirectional and fixed antenna bandwidth insufficient • Helical gain per unit mass less than parabolic • 2.5 m steerable parabolic antenna selected • Color TV transmission from asteroid @ 1.6 kW radiated power Omnidirectional Antenna Helical Antenna Fixed Parabolic Steerable Parabolic
Timeline • Closest Approach Date: May 24, 2024 • Arrive at LEO – December 16, 2023 • Depart from LEO- February 8, 2024 • Arrive at Asteroid – May 18, 2024 • Depart from Asteroid – June 17, 2024 • Arrive at LEO – September 25, 2024
Mission Strengths • Low technical risk • High artificial gravity reduces medical risk to crew • Easily accessible target • Lays groundwork for future human missions in deep space.
Sources-1 • Advanced Life Support Requirements Document. NASA: Lyndon B. Johnson Space Center, Crew and Thermal Systems Division. Feb. 2003. • Chang-Diaz, Franklin R., et. al. Rapid Mars Transits with Exhaust-Modulated Plasma Propulsion. NASA Technical Paper 3539. Mar. 1995. • Depleted Uranium: Sources, Exposure, and Health Effects. World Health Organization. Apr. 2001. • G.R. Longhurst, B. G. Schnitzler, B. T. Parks, Multi-Megawatt Power System Trade Study, Nov. 2001. Idaho, LLC. • Glover, Tim W., Franklin R. Chang-Diaz, and Andrew V. Ilin. Projected Lunar Cargo Capabilities of High-Power VASIMR Propulsion. 30th International Electric Propulsion Conference. Sep. 2007.
Sources-2 • Human Space Exploration Update: Bigelow’s C1 and C2 Set. Everest Explorers Web. <http:// www.explorersweb.com/everest_k2/news.php?id=18079>. Hyland, David. kepler.m, AsteroidTrajectLoT.m, AsteroidEulerHillLoT.m. MATLAB code. Nov. 2010. • JPL Small-Body Database. Jet Propulsion Laboratory. < http://ssd.jpl.nasa.gov/sbdb.cgi>. • Joosten, B. Kent. Preliminary Assessment of Artificial Gravity Impacts to Deep-Space Vehicle Design. Feb. 2007. NASA: Lyndon B. Johnson Space Center. • Lackner, J.R., and P. DiZio. Artificial Gravity as a Countermeasure in Long-Duration Spaceflight. NIH: 2000.
Sources-3 • Landis, Geoffry A. Magnetic Radiation Shielding: An Idea Whose Time Has Returned? 10th Biennial SSI/Princeton Conference on Space Manufacturing. May 1991. • Larson, Wiley J., and James R. Wertz. Space Mission Analysis and Design. 3rd ed. Microcosm, 1999. • Nuclear Material: DOE Has Several Potential Options for Dealing with Depleted Uranium Tails, Each of Which Could Benefit the Government. Government Accountability Office. Mar. 2008. • Radiation Shielding. Sharp Mfg. < http:// www.nuclead.com/radiationshielding.html>. • Ultra-High Molecular Weight Polyethelyene. Shielding Solutions. < http://www.radiationshieldingsolutions. com/ shielding_solutions_neutron_shielding.html>.