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Weekly Summary Asteroid Sample Return. Spring Semester March 5, 2008 Ashley Chipman. Last Week. GN&C Wrote matlab program to iterate approach trajectory to determine: Delta v’s Time on approach orbit Impact accelerations Researched star tracker w/info from Steve
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Weekly SummaryAsteroid Sample Return Spring Semester March 5, 2008 Ashley Chipman
Last Week • GN&C • Wrote matlab program to iterate approach trajectory to determine: • Delta v’s • Time on approach orbit • Impact accelerations • Researched star tracker w/info from Steve • Gave initial weight estimates for all sensors to Structures • Propulsion • Picked quantity (4) and arrangement (about center of mass) of hydrazine rocket clusters • Determined Isp of 220 to 230s • Identified mass vs. fuel relations with rocket equation • Identified means of finding required fuel volume for Delta-v maneuvers • Researched fuel tanks • Structures • Trade study on driving force for landing spikes • Continue ANSYS work on landing stresses • Determine materials for structure of aircraft for trade study.
Outstanding Issues • Further spike testing (frozen) • Attitude Control Fuel
Next Week • GN&C • Finalize star tracker, altimeter, and imu that will be used to obtain weights • Work w/other groups to finalize approach and altitude of vertical drop • Start high level control systems architecture • Propulsion • Identify specific thrusters from distributors • Incorporate available thrusters into Matlab design code & select based on force reqs • Consider angular velocity capabilities of attitude thrusters • Look into methods of maintaining center of mass during fuel tank depletion • Investigate propulsion schematic (pyro-valves, latch-valves, solenoid-valves, service valves, pressure transducers, orifices, cryo-joints, and filters) • Structures • Different layouts for spacecraft structure (body and landing) • Thermal calcs and C.G. approximations • Further testing for spikes • Nail 3” long and 1/4” diameter (frozen ground)
Details of Attachment • Mechanical Attachment • Hilti Gun DX E72 • 2.0 kg (assuming necessary mechanics similar in wt) • Highest power .22 • Wt of 40 grains • Muzzle velocity of 2020 ft/s • Results: • 2.59 g and 615.7 m/s, yields momentum of 1.595 Ns • Delta V from ignition of V=4 (1.595/wt) • Final Specs • 14 kg and delta V between 0.008 and 0.012 (750 kg and 500 kg wt)