Transcript EDL Development Needs

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
–
•
Driving considerations for MinMars:
–
–
–
•
Primary drives is science access
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
2000 kg payload
MSL reference
MSL Technology Extension for Ballistic Coefficient 115 kg/m2
Delivery of ~2000 kg of usable
payload achievable with MSL
techn. (see NASA Mars DRA 5.0)
2 mt lander based on MSL technology
4.6 m
7.3 m
•
•
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
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
Parameter
MinMars reference design
NASA MSL
Entry mass [kg]
25000
2800
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]
10 - 20 degrees (estimate)
-15.2
Trim angle of attack during entry [degrees]
-18.5
-15
Entry attitude control
3-axis RCS
3-axis RCS
Entry guidance
?
Apollo guidance algorithms
Ballistic coefficient [kg/m2]
433
115
Hypersonic L/D at angle of attack [-]
0.3
0.22
Landing accuracy, 3 sigma [km]
2 - 5 km
~ 20 km
Landing altitude [km]
< 0 km MOLA
Up to 2 km MOLA
Aeroshell diameter [m]
7
4.6
Final landing system
Descent stage
Main parachute and skycrane
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)?