The Challenge of Mars EDL (Entry,Descent, and Landing)

Ron SostaricNASA Johnson Space Center

AlAA Senior MemberApril 2010

https://ntrs.nasa.gov/search.jsp?R=20100017668 2018-02-03T13:06:00+00:00Z

n The information contained in this presentation reflects thecollective wisdom and experience of a large number ofindividuals across the EDL community. It would be very difficultto attempt to list them all individually without missing a majorcontributor.

n However, I would like to acknowledge Carlos Westhelle of NASAwho directly provided much of the data shown here.

2

4 Ares-V Cargo

Launches

Ares-I Crew Launch

3 Ares-V Cargo Launches

40

In-Situ propellant production for Ascent V

Aerocapture / Entry, Descent & Land Ascent Ve

Aerocapture Habitat Landerinto Mars Orbit ©- -

©

Cargo:

350 days

to Mars

to EDLTTF-IMre for Trans-Earth Injection

OCrew: Use Orion totransfer to Habitat Lander; thenEDL on Mars

QCrew: Jettison droptank after trans-Mars injection-180 days out to Mars

Crew: -180 daysCa rgo Crew

back to EarthVehicles Transfer

-L Vehicle

-26 -30

NOW if,

months months ^-Orion direct

-^ — - — — Earth return

ATMOSPHERE:• Thin Martian atmosphere (surface density equivalent to Earth's at 30

km)

• Too little atmosphere to decelerate and land like we do at Earth• Atmosphere is thick enough to create significant heating during entry

125

100

75

Almude 7km

50

• Lack of understanding of the atmosphere: 25

• Aerodynamics, aeroheating, winds, and density variations-5 kn X.,

5 10 15 20 25

R/Pnc" f

50% 2010%4n

(0 GEAR RATIOS:• All Propulsive: 1 metric ton (MT) on surface of Mars requires 20 MT in Low Earth

Orbit (LEO). This would lead to unreasonably large masses in LEO.

• Using the Atmosphere allows a significant reduction in the gear ratio

• 1 MT on surface of Mars requires 5-6 MT in LEO

WILL IT WORK?So far all potentially feasible human-scale Mars EDL architectures require thesuccessful development of SEVERAL low TRL elements.

There are many promising ideas that need assessment and testing. Theseinclude:

• Large rigid heat shields (10m diameter by 30m length)

• Inflatable heat shields (20 to 25 m diameter)

• Inflatable aerodynamic decelerators

• Supersonic retro-propulsion

• Precision landing5n

Spirit

7W j

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Phoenix60' Ilikinn /I

Pathfinder

Viking

Opportunity

W

0,

-30'

-60

180 240 300: 0, 60 120: 180--

-8000 -4000 0 4000 8000

All six of the successful U.S. Mars EDL systems had:

• Low Landing Site: elevation sites below —1 km MOLA ^— that 's Mars Sea Level

• Low Mass: Had landed masses of less than 0.6 MT

• UNGUIDED: Had large uncertainty in targeted landing location (300 km forMars Pathfinder, 80 km for MER)

Mars Science Laboratory (MSL) '11 EDL Architecture:

• Low Landing Site: Landed elevation requirement for sites below 0 km MOLA

• Low Mass: Has landed mass of 0.9 MT

• GUIDED: Has uncertainty in targeted landing location of 10km

HUMANS need more capability:

Ch • All of the current Mars missions have relied on large technologyinvestments made in the late 1960s and early 1970's as part of the VikingProgram (heatshield shape, thermal protection material, and parachute)

• Large Mass (Entry Mass of — 100 — 150 MT)

• Higher elevations — interesting science

• Precision Landing

Previous Viking derived EDL systems and the thin Martian atmosphere and small scale heighthave limited accessible landing sites to those below -1.Okm MOLA

To date the southern hemisphere has been largely out of reach (approximately 50% of theplanet surface remains inaccessible with current EDL technologies)

-40100 -2000 0 2WO 4000(Courtesy of Rob Manning, JPL) AJtttude Above NAG LA Areald (m)

8n

MOLA 1/4 0 Topographic Data

i^ rt

4n' ;;as

30rnaa 15

0

-60 _ +^

-75.90-_0 50 100 150 200 250 300 350

East Longitude (deg)

< 1.0 km (65% of Surface)

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0 50 100 150 200 250 300 350

East Longitude (deg)

< 2.5 km (90% of Surface)

90

75 —

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^ 0

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-45

-60

-75

900 50 100 150 200 250 300 350East Longitude (deg)

< -1.0 km (45% of Surface)

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9

MSLViking MPF MER Phoenix

Core Viking Technologies.700 sphere-cone aeroshell

Parameter Viking MPF VIER Phoenix MSL

Entry Mass (kg) / Ballistic Coeff. (kg/m l ) 980/66 585/63 836/90 603/65 3257/140

Lander/Rover Mass (kg) 612 11 173 64 850

Aeroshell Diameter (m) 3.5 2.65 2.65 2.65 4.5

Angle-of-Attack (deg) / L/D 11.1-/0.18 0./0.0 0./0.0 0./0.0 -15.5° / 0.24

Peak Heatrate (W/cm z ) 21 106 44 59 <210

Parachute Diameter (m) 16.15 12.4 14.1 11.5 19.7

Landing Site Elevation (km) -3.5 -1.5 -1.3 -3.5 0.0

10

0 0

Human

100-150 MT/150-600 kg/m2

' 40-50 MT

1L 30

0 . _0;8).

MSL

Core Viking Techr'700 sphere-cone a.SLA-561V TPSSupersonic DBG parac

Parameter

Entry Mass (kg) / Ballistic Coeff. (kg/ml ) °; .

Lander/Rover Mass (kg)

Aeroshell Diameter (m)

612

3.5

Angle-of-Attack (deg) / L/D 11.1° / 0.150°,

Peak Heatrate (W/cm') 21 106

Parachute Diameter (m) 16.15 12.4

Landing Site Elevation (km) -3.5 -1.5

Engineering 11

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sti

Mach 5 Mach 10 iylaclr 15

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When entering from lowMars orbit, start here.

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Subsonic parachute inflation"Mach - dynamic pressure box"

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'Supersonic parachute inflationti "Mach - dynamic pressure box" \

^ I Subsonic propulsionMach - thrust/weight box"

5

500 10030 1-00 1000

Goal is to land here.

Cat 1

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force

Cat 5

Hurricane

force

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tart subsonic propulsive descent here (< 1 km AGL)

1000 1300 2000 2300 3000 3300

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AIt.(Krn M0LA)

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Mach 5 , Mach 10 I I S

II I II II II II

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Entry at 3400 m/s

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Supersonic parachute inflation"Mach - dynamic pressure box"

I I I Supersonic Decelerator '"gap"I

ti t

Mach 15 li y

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Tecnnology bap:This gap can be closed using a

supersonic aerodynamic orpropulsive decelerator.

500 1000 1100 ^JJI LJOO 300 -)JO

Without new technologies we have surface impact at Mach 2.5

14

01 M mom Ah Ah so

n Technologies that can help close the "gap"— Rigid Aeroshell— Inflatable Aerodynamic Decelerator (IAD)— Supersonic Retro-Propulsion

n Other technologies of interest— Aerocapture— Precision Landing— Hazard Detection and Avoidance

15M

n Technologies that can help close the "gap"— Rigid Aeroshell— Inflatable Aerodynamic Decelerator (IAD)— Supersonic Retro-Propulsion

n Other technologies of interest— Aerocapture— Precision Landing— Hazard Detection and Avoidance

16M

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Low LrD, AerodynamicSurface Control

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Low Beta, Mid L/D TrajectoryH ac h 5 ` , I H ach 10 , Mach 15

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With large enough inflatables,it may be possible to achievesubsonic speeds in some cases

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30- 40 m diameterinflatable or otherpersonic drag system

4 5ti

tit ti, +,ti

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500 HOOD 1500 1000 4- 0

19

n Advantages:• More precise landing — aerodynamics / winds now secondary effect• Control authority and altitude from Mach > 3 to the ground• Fewer complex systems (e.g.parachutes, deployable systems)

n Disadvantages:• Large propellant mass fractions• Aerodynamic stability of the vehicle plume and flow impingements• RCS / flow interactions

— Aerodynamic / propulsion flow interactions— Plume/ flow aeroheating

• Surface contamination issues

20

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Some possible combinations...

A*-%sow

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MIMI21

n Technologies that can help close the "gap"

— Rigid Aeroshell— Hypersonic Inflatable Aerodynamic Deceleration (HIAD)— Supersonic Retro-Propulsion

n Enabling technology

— Aerocapturen Risk reduction and performance enhancement

— Precision Landing— Hazard Detection and Avoidance

22

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24

n Precision landing is the capability to land very accuratelyn Requires very good knowledge of the vehicle state (navigation) at the right

time, in addition to the ability to correct for state errors (guidance andcontrol)

n A combination of sensors including star tracker, inertial measurement unit(IMU), altimeter, and velocimeter are used for state estimation

n Terrain Relative Navigation is a technology being developed for the Moonand Mars which may enable a precision landing level of performance

25

n HDA is the capability to detect and avoid hazards during the landingn An onboard hazard map is developed real time during the descent using

flash LIDARn The flash LIDAR returns a 3-D image of the landing area which contains

higher resolution information of the landing area than currently possibleusing orbit reconnaissance

n An updated landing point is then selected (either automatically or via crewintervention) and the vehicle re-targets to the new landing point

26M

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*-------0.9m radiushemispheres

r0.6m radiusiemispheres—,►

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SHIMMIES

n Current state of the art has a gap for large robotic (> 1 MT) and humanMars EDL

n NASA is developing a number of promising technologies that may eliminatethe gap and enable future missions to Mars

n In addition, a general planetary capability for Safe and Precise Landing isbeing developed under the ALHAT (Autonomous Landing and HazardAvoidance Technology) project

28

BACKUP

IN

n For 50-100 MT entry masses we need a 20-40 m diameter aeroshell.n Large uncertainties (unknown-unknowns):

— Lift control (how to modulate drag) with large density uncertainties— Dynamic stability issues at supersonic and transonic conditions— Subsonic position correction— Subsonic separation mechanism

Specifically for an Inflatable Hypersonic Decelerator:— Lift control— RCS— Fluid structures interactions— Light weight flexible TPS with large radiative heating

Specifically for a Rigid On-orbit-deployed Hypersonic Decelerator:— Mass fraction of Aeroshell & deployment device

n Again, there are NO Earth analog for these systems.— NASA, Russia and ESA have tested very small scale inflatable Earth entry systems (IRVE,

RDT)

30