MARS DROP. Matthew A. Eby Mechanical Systems Department. Vehicle Systems Division/ETG The Aerospace Corporation May 25, 2013

Transcription

1 MARS DROP Matthew A. Eby Mechanical Systems Department Vehicle Systems Division/ETG The Aerospace Corporation May 25, 2013 The Aerospace Corporation 2013

2 The Aerospace Corporation (Aerospace), a California nonprofit corporation has flown 20 small satellites over the past 15 years. 2 Photograph courtesy of NASA

3 MARS DROP Landing System for a Mars Planetary Micro-probe Objective MARS DROP is an Aerospace research project to adapt Aerospace s REBR (Reentry Breakup Recorder) vehicle for use as a Planetary micro-probe Existing aeroshell is well suited for Mars entry (aerodynamically stable) Simply need to add a landing system Research objective to demonstrate proof-ofconcept landing system that leaves sufficient volume for a useful scientific payload. Approach Engage with scientific community from outset Collaboration with Planetary Science Institute Architect three aspects Backshell separation mechanism Deployment of aerodynamic drag device Terminal landing hardware Test on Earth with high altitude balloon deployments REBR Key Milestones Landing Architecture Study Fall 2012 First High Altitude Field Test Soon Complete Detailed Design Fall 2013 Final High Altitude Field Test

4 Entry, Descent, & Landing 7 Minutes of Terror Progressively larger NASA Mars Landers have produced progressively more exciting landings (e.g. MSL s 7 Minutes of Terror ) Larger mass densities equate to higher ballistic coefficients and faster terminal velocities, requiring complex multi-stage, supersonic deceleration Multi-stage, supersonic deceleration is untestable as a system on Earth (cost prohibitive) A micro-probe has the advantage of going smaller, with a low ballistic coefficient that greatly simplifies the landing architecture. A sufficiently low ballistic coefficient will produce a subsonic terminal velocity, requiring a simple, single-stage, subsonic deceleration to reach landing velocity Single stage, subsonic deceleration is easily tested on Earth Drop testing at high altitudes (where atmosphere has same density as Mars surface) Chute Deploy ~ Mach 0.8 Chute Deploy ~ Mach 2 Pathfinder / MER / MSL 4

5 Mach Number Entry, Descent, & Landing Ballistic Mars Entry Curves Pathfinder, 68 kg/m 2, Entry at 7.3 km/sec & DOF Simulation (Range, Height, Orientation) Spirit/Opportunity, 97 kg/m 2, Entry at 5.5 km/sec & Parachute Window Mars DROP, 35 kg/m 2, Entry at 6.9 km/sec & * 5 Altitude (km) Mach 1 Microprobe goes subsonic around 10 km subsonic landing system Pathfinder, Spirit, Opportunity, MSL all supersonic during parachute deploy *Microprobe goes subsonic across wide range of entry parameters

6 Aerodynamic Decelerator Trade Study Available Volume is the Limiting Factor Concepts: Solid Circular Parachute Disk-Gap-Band Parachute Inflatable Decelerator Vortex Ring Parachute Parawing Claim to Fame Standard Round Solid Parachute Used on all NASA Mars Landers Targeted for future NASA Mars Landers Highest Drag Supersonic No Yes Yes Unreliable No Gliding Chute Complexity Low Low High High (Swivel) Medium Prior Research Extensive Extensive Moderate Minimal Moderate Subsonic Drag Moderate (C D ~ 0.9) Mass / Volume for 7.5m/s vertical velocity (reference V) Notes / Landing Site Limitations Low (C D ~ 0.6) Moderate (C D ~ 0.8) Very High (C D ~ 2.0) Very Low (C D ~ 0.3), but Lift 1.1 kg / 2300 cm kg / 3480 cm kg / 5200 cm kg / 1050 cm kg / 200 cm 3 Poor subsonic drag prompts two-stage deceleration Is attractive for much larger vehicles Suspect Reliability Horizontal velocity -could be good or bad 6 ~ 3000 cm 3 internal volume

7 Why a Parawing Back to the Future NASA studied parawings in the 1960 s for Gemini & Apollo reentry vehicles, but ultimately did not employ them. For a Mars microprobe they are attractive We are volume limited, so the Lifting action (L/D ~ 3) sets up a glide path that greatly reduces the vertical landing velocity By far smallest volume amongst options We have a subsonic deployment and deceleration, where parawings are usable Extensive existing database of aerodynamic characteristics for microprobe design sizing Steerable & will glide for km! Image Courtesy of NASA 7

8 Parawing Challenges and why Gemini astronauts never glided back home It kicks like a mule during inflation, 2-3 times higher transient loads than an equivalent circular chute But lightweight instruments designed to MAC (Mass Acceleration Curve) launch loads should be able to handle this better than astronauts It s a bit of a packing nightmare, with 275 feet of rigging line But the advent of high performance synthetic fibers (Spectra) keeps the stowed volume small 8

9 Landing Architecture Entry Interface 100 km, V=7km/sec T+1 min, Max Q 35 km, 15 g s T+3 min, Backshell Sep. 6.5 km, Mach DOF Simulation (Range, Height, Orientation) T+3 min, Main Deploy 6.5 km, 200m/sec T+3 min, Peak Inflation Load 6.5 km, 65 g s T+10 min, Terminal Landing 3.0 km, Vertical < 7.5 m/sec Foreground Image Courtesy of NASA 9

10 High Altitude Testing Going to Mars on Earth Low density Mars surface atmosphere is replicated on Earth at high altitude (~100,000 feet), reachable for small payloads with weather balloons Test in stages Deployment tests of the Parawing across Q (dynamic pressure) bounds Proof-of-concept demonstrations for the full landing system Transition capability to mission development Approach yields high fidelity testing at minimal cost Small fraction of cost traditionally expended for verifying a descent and landing architecture 10

11 Test Architecture Release Target Drop Altitude 90k 100k feet Accelerate to Dynamic Pressure Launch Conduct Test Beacon 430 MHz Position & Telemetry MHz 11

12 Let s Propose a Mars Mission Together Some Design Parameters REBR has a history of riding on NASA & ESA spacecraft Who wants to try to hitchhike on a forthcoming Mars bound spacecraft? The parawing is sized to land a 3 kg probe (~1 kg available for the science payload) at most elevations on Mars Who wants to target an interesting but risky location the expensive rovers steer clear of? A parawing is steerable and will glide for kilometers over 10 or more minutes Who wants to fly into Valles Marineris? It s a Cubesat in a reentry package, so its pretty cheap (relatively speaking) Who wants to send a dozen as a distributed science project (weather, seismic, etc.)? 1.) Pick any Location (almost) 2.) Select the Science 3.) Design for Launch & EDL Packed Chute / Backshell Adhere to those Mass Acceleration Curve Loads (~60 g s) Range Enabled Science Probe / Forebody? 12 Map Courtesy of NASA ~ 3000 cm 3 internal volume

13 M RS DROP LET S DISCUSS COLLABORATING 13

14 References 1. NASA Technical Note D-5965 LOW-SPEED WIND TUNNEL INVESTIGATION OF ALL-FLEXIBLE TWIN- KEEL TENSION-STRUCTURE PARAWINGS, NASA Technical Note D-5793 PERFORMANCE AND DEPLOYMENT CHARACTERISTICS OF A TWIN-KEEL PARAWING WITH VARIOUS AMOUNTS AND PERMEABILITIES OF POROUS MATERIAL IN OUTER LOBES,