Review of Past and Proposed Mars EDL Systems

Past and Proposed Mars EDL Systems MinMars Mars entry body design is derived from JPL Austere Mars entry body design (blue fields fixed) MinMars entry velocity may be higher due to direct entry –May need to perform aerocapture prior to Mars entry?

JPL Austere Mars Entry Body 30 degrees side-wall angle

High Ballistic Coefficient Mars Entry (JPL Austere)

MSL is designed to support landing altitudes as high as 2 km MOLA –Primary drives is science access Driving considerations for MinMars: –Solar power system performance, drives towards 30 deg N –Soil / ground water content –Facilitation of Mars EDL It seems that the MinMars considerations can be supported by landing sites with -2 km MOLA or less

EDL System for 2 mt Useful Mass

MSL reference MSL Technology Extension for Ballistic Coefficient 115 kg/m 2 Delivery of ~2000 kg of usable payload achievable with MSL techn. (see NASA Mars DRA 5.0) 2000 kg payload

4.6 m 7.3 m 2 mt lander based on MSL technology

Transportation assessment assuming capability for 1 mt usable surface payload Crew transportation: –2 crew per 25 mt package –In-space habitat that is discarded prior to aerocapture / entry –2 crew either enter together in single aeroshell or each crew has individual aeroshell Transportation of supplies and spare parts –Can be scaled down and delivered with individual aeroshells in 1 mt packages Transportation of power and ISRU systems –Can be scaled down and delivered with individual aeroshells in 1 mt packages Transportation of unpressurized mobility systems –Can be scaled down and delivered with individual aeroshells in 1 mt packages Transportation of habitat and workshop –Difficult, may require inflatable modules with interior outfitting; subsequent assembly on the surface ?

EDL System for 8 mt Useful Mass

EDL System for 45.9 mt Useful Mass

Basis: JPL Austere Mars Entry Body 30 degrees side-wall angle

Backup Slides

ParameterMinMars reference designNASA MSL Entry mass [kg] Payload mass fraction [-]0.4 (10 mt out of 25 mt)0.29 (0.8 out of 2.8 mt) Entry velocity [km/s]4.7 (from orbit) or 7-8 (direct)6 (direct) Entry angle [degrees] degrees (estimate)-15.2 Trim angle of attack during entry [degrees] Entry attitude control3-axis RCS Entry guidance?Apollo guidance algorithms Ballistic coefficient [kg/m2] Hypersonic L/D at angle of attack [-] Landing accuracy, 3 sigma [km]2 - 5 km~ 20 km Landing altitude [km]< 0 km MOLAUp to 2 km MOLA Aeroshell diameter [m]74.6 Final landing systemDescent stageMain parachute and skycrane Mars Science Laboratory (MSL) and MinMars Entry, Descent & Landing (EDL) comparison Vehicles and crew member notionally to scale MSL data from: Mars Exploration Entry, Descent and Landing Challenges, Braun RD, Manning RM, 2006

Major EDL Challenges for MinMars Significantly higher ballistic coefficient than MSL –Lower landing altitude than for MSL helps (denser atmosphere) –Landing altitude possibly as low as -2 km Higher landing accuracy –2-5 km vs. 20 km –But pre-deployed assets available (in orbit and on the ground) No use of main parachute(s) –Vehicle never slows down sufficiently for existing parachute technology (< Mach 2); also issues with chute scaling –All-propulsive descent will likely be required –Possibly use of a supersonic drogue parachute for aeroshell forebody separation and stabilization Off-center aerodynamic heating –Large aeroshell diameter leads to different Re-number regime, turbulent flow over forebody heat shield –Maximum heating may no longer occur at center / nose of heat shield but off-center in turbulent region Question: in a worst-case scenario, could we deliver MinMars infrastructure and crew with existing (Viking-based) EDL technology (or extensions thereof)?