Asteroid Sample Return Progress as of 3/12/2008

GN&C Sensor Data

Star Tracker Galileo Avionica A-STR Autonomous Star Tracker FOV: 16.4 X 16.4˚ Power Consumption: 8.9 W at 20˚C 13.5 W at 60˚C Size: 195 (L) X 175 (W) X 288 (H) mm Mass: 3 kg

IMU Honeywell Miniture IMU Mass: 5 kg Size: Unknown Power Consumption: Unknown This device has very little information available to us.

Altimeter Yet to be decided upon discussion with Steve

High Level Control System Control Inputs – Reaction Jets Vehicle Dynamics Sensors -Star Tracker -IMU -Altimeter Planned Trajectory

Telecomm Waiting for answers to questions

Approach of Asteroid GN&C has developed a code that gives the required delta v based on the point where the free fall begins. This will be finalized once the structures group determines what impact loads are acceptible.

Propulsion Propulsion has developed a code to determine fuel needs based on the delta v requirements and thrust for attachment. Code provides suggestions for tanks and thrusters required for mission based on data retrieved through web research of thrusters and tanks. Final fuel requirements are based on thrust requirements for attachment, which depends on final structure design

Structures Work so Far

Force needed to hold Spacecraft

Finding Needed Torque offset due to drill

Initial Sketch of Spike and Holding Method Spike 3 inches in length and ¼ inch in diameter Spike exits through hole in foot and head of spike clamps down on foot Barbs on spike increase surface area and holding power in ground

Attachment Method Use Mechanical fastening system based on Hilti Gun model DX E72. Assume built weight for guns to be same as hilti gun. Use F=m(v/t) to determine force from anchor deployment. t is assumed to be.01 s Determine required Thrust and Fuel based on Force. Deploy one anchor at a time to reduce thruster requirements. Assume 30s to deploy all 4 anchors Use _____ Anchor based on research.

Hilti Gun DX E72.22 caliber powder actuated fastening tool Drives up to 2.8” nails into concrete or steel 2 kg each Modify Design using space worthy materials

Reaction Force Ballistics information found at: Used: Remington.22 Short CB Cap Bullet Weight = 1.87 g Velocity = m/s Force from Attachment = (213.36/.01)*(1.87/1000)=39.898N per anchor

Thrust and Fuel Requirements Using Moments = 0 and forces = 0 T1=40(L/L=a) + (40-M) T2=40(L/L=a) - (40-M) T1 – thrusters on same side as anchor T2 – thrusters on opposite side as anchor M – Mass*g g=.006

Anchor Specifications Ideas

Trade Study (Final trade study between mech. And thruster methods will go here) At this point estimated fuel usage for 24 hr bun is ~ 300kg

Initial Trade Study IdeaHow worksProsCons Spikes on ImpactDrive stakes in when land from legs Don’t need separate propulsion system (less weight) Highest probability for success Leaves nothing behind HarpoonShoot something out and reel ourselves in Compensation torques Probably use more fuel Way more mechanisms involved Probably get tangled to roll back up. Thrusters Propulsion Only Use thrusters to hold in place Extra fuel Torque when drilling Need momentum wheel, “spikey feet” Cork Screw Spikes Post-ImpactTwo arms with small explosion that would rotate and come back while nailing into the ground Would work…kinda Able to retry Even more complicated than harpoon

Initial Trade Study Cont. ThrustersHarpoonSpikes on ImpactSpikes Post- Impact Corkscrew Weightbad goodishokayBad Mechanical Complexity Good (best) BADgoodokayBAD Fuel Consumption BADgood okaygood Power Requirements goodbadgood Bad DependabilitygoodbadokaygoodBad Applied Loadsgood badokaygood Reusabilitygoodbad okay Methods in bold font further researched to come to final decision.

Mass Budget Mass budget is under construction.