MSL Entry, Descent,
and Landing
Instrumentation
(MEDLI)
Programmatic Review
Neil Cheatwood, Principal Investigator
Mike Wright, Deputy Principal Investigator
Alan Little, Project Manager
Mike Gazarik, Deputy Project Manager
Helen Hwang, Deputy Project Manager
Jeff Herath, Chief Engineer
22 March 2007
22 March 2007
1
Project Formulation Overview
22 March 2007
2
MEDLI Rationale
• MSL is taxing the limits of current modeling capabilities for Mars entry missions
Aeroheating uncertainties are greater than 50% on heatshield, due to early transition to
turbulence, surface chemistry, and ablation induced roughness.
• A primary source of uncertainty is a lack of relevant flight data for improved model
validation
A small amount of TPS data was obtained from Pathfinder, but no direct measurements of
aeroheating, aerodynamics, or atmosphere.
• MEDLI instrumentation suite will collect an order of magnitude more EDL data than all
previous Mars missions
– Thermocouple and recession sensor data will define aeroheating uncertainties and
reduce TPS risk for future missions, and will determine performance limits of heritage
materials.
– Pressure data will permit accurate trajectory reconstruction, separation of aerodynamic
and atmospheric uncertainties in the hypersonic and supersonic regimes.
– MEDLI flight data is relevant to Orion since its Block-I backup TPS options include the
same material (SLA-561V), in a similar heating/shear stress environment, as MSL.
22 March 2007
3
Project Initiation
• Entry, Descent, and Landing (EDL) instrumentation study conducted by NASA
EDL team in July 2006
• Constraint set provided in August 2006 by SMD/Mars Exploration Program &
MSL Project to minimize/control risk, and provide a basis for analyses
• “Formalized” into Flight Project in September 2006 with LaRC as Project
Manager, ARC as Deputy Project Manager
• Baseline architecture briefed to ARMD/ESMD/SMD October 5th, 2006
– Excellent progress led to authorization to investigate enhanced option
• Final architecture briefed to Science, Exploration, and Aeronautics Directorate
AA’s on October 25th, 2006
– Authority to proceed given with implementation guidelines/constraints and a final
decision gate
• Final Authority to Proceed given at the Agency Program Management Council
Meeting on November 2nd, 2006
22 March 2007
4
System Overview
MEDLI Chief Engineer
Jeff Herath (LaRC)
22 March 2007
5
Description & Top Level Technical Objective
MEDLI is an instrumentation suite installed in the
heatshield of the Mars Science Laboratory’s (MSL) Entry
Vehicle that will gather data on the atmosphere and on
aerothermal, Thermal Protection System (TPS) and
aerodynamic characteristics of the MSL Entry Vehicle
during entry and descent providing engineering data for
future Mars missions.
Thermocouples
Pressure Sensors
Recession Sensors
22 March 2007
6
MEDLI Operations Concept During MSL EDL
MSL EDL Outline
MEDLI Active:
Atmospheric Interface t-10min
MEDLI Data
Transmitted
MEDLI is taking data and MSL
is storing the data in the Rover
for transmission after landing
MEDLI Inactive:
Atmospheric Interface t+4min
22 March 2007
7
MEDLI System Description
Cruise Stage
• MEDLI consists of 7 pressure ports and 7
Backshell
integrated sensor plugs (containing four
thermocouples and a recession sensor) all
installed in the forebody heatshield of the MSL
entry vehicle.
• These sensors are wired to a Sensor Support
Electronics (SSE) box, that provides power to
the sensors and conditions and digitizes the
sensor signals, which are sent to MSL’s
Descent Stage Power and Analog Module
(DPAM) and are then sent to the Rover
Compute Elements over the MSL EDL-1553
bus for storage until the data is telemetered
back to Earth after landing.
Descent Stage
Rover
Heatshield
MSL (For Reference)
Backshell
cutter
Descent Stage
DPAM
Power
RS422 Serial
cutter
Rover
1553 Bus
RCE-A
RCE-B
cutter
Heatshield
RS422 Serial
28v Power
Sensor Support
Electronics
Heatshield Sensors
22 March 2007
8
MEDLI Consists of Three Main Subsystems
•
MEDLI Instrumented Sensor Plug
(MISP)
–
–
•
Outer kapton layer (tube o r coating)
Hollow kapton tub e
Recession Sensor
Thermocouple Plug
Each plug consists of 1 recession
sensor and 4 thermocouple
sensors
Mars Entry Atmospheric Data
System (MEADS)
–
•
A plug consists of 1.3” diameter
heatshield Thermal Protection
System (TPS) core with embedded
thermocouples and recession
sensors
Wound resistive wire
Series of through-holes, or ports,
in TPS that connect via tubing to
pressure transducers
Mars Entry Atmospheric
Data System
Sensor Support Electronics (SSE)
–
Electronics box that conditions
sensor signals and provides
power to MISP and MEADS
Sensor Support Electronics
22 March 2007
9
MEDLI on Heatshield w/ Backshell & Rover
Rover
MISP (1 of 7 Plugs)
22 March 2007
SSE
MEADS (1 of 7 Ports)
10
Science Objectives
22 March 2007
11
MEDLI Top Level Flight Science Objectives
Overview
MEDLI is an instrumentation suite to be
installed in the heatshield of the Mars
Science Laboratory’s (MSL) Entry Vehicle
that will gather data on its aerothermal,
aerodynamic, and thermal protection
system (TPS) performance, as well as
atmospheric density and winds, during
entry and descent, and will provide
engineering data for all future Mars
missions.
Aerothermal & TPS
– Verify transition to turbulence
– Determine turbulent heating levels
– Determine recession rates and subsurface
material response of ablative heatshield at
Mars conditions
22 March 2007
Aerodynamics & Atmospheric
– Determine density profile over large
horizontal distance
– Determine wind component
– Separate aero from atmosphere
– Confirm aero at high angles of attack
12
MEDLI Measurements:
Sensor Placement Strategy
Aerothermal/TPS Objectives
Req
ID
363a
363b
364
365
366
367
368
369
Technical Objectives
Basic Aeroheating
Stagnation Point Heating
Turbulent Leeside Heating
TPS Recession Rate
Windside Heating Augmentation
TPS Total Recession
Subsurface Material Response
Turbulent Transition
Location
T3 T4 T5
T1
T2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
T6
T7
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Aerodynamics/Atmosphere Objectives
Req
ID
371
372
373
374
375
22 March 2007
Technical Objectives
Basic Surface Pressure
Angle of Attack
Angle of Sideslip
Dynamic Pressure
Mach Number
P1
P2
X
X
X
X
X
X
Location
P3 P4
X
X
X
X
X
P5
P6
P7
X
X
X
X
X
X
X
X
13
MEDLI Objectives: Aerothermal
• Basic and Stagnation Region Aeroheating (PS-363)
– Justification
Re-creation of heating distribution increases confidence in aerothermal predictive tools.
– Implementation
All seven plugs are located to enable profile reconstruction (including stagnation point,
streamline tracing, asymmetry).
• Turbulence and Transition (PS-364, PS-366 & PS-369)
– Justification
Transition on leeside predicted prior to peak heating. Predicted turbulent heating more
than a factor of two higher than maximum laminar heating, and uncertainty is higher.
– Implementation
• Five of the seven plugs located to detect peak heating levels, profile, and transition time.
• Two plugs located to detect possible windside transition.
Engineering Impact
• First in-situ model validation of flight aeroheating tools will lead to better uncertainty
quantification and margin clarity for future Mars entry missions.
• Validation of turbulent heating predictions will reduce the uncertainty that drives large vehicle
TPS sizing.
22 March 2007
14
MEDLI Objectives: TPS
• Recession Rate and Integrated Total (PS-365 & PS-367)
– Justification:
This is the primary remaining TPS response uncertainty for Mars entries (SLA-561V).
– Implementation:
• HEAT isotherm sensors track an isotherm through the material as a function of time.
• Recession reconstructed via calibration and analysis.
• Subsurface Material Response (PS-368)
– Justification:
TPS thermal response model is developed and validated with arc jet testing in air.
Improved model validation requires in-situ data in Mars atmosphere.
– Implementation:
Thermocouples and HEAT sensor data will be compared to theoretical predictions of indepth temperature response.
Engineering Impact
• First in-situ validation of TPS response in Mars atmosphere.
• Reduction of TPS design margins and expansion of performance envelope for future Mars
entry missions.
22 March 2007
15
MEDLI Objectives: Atmosphere and Aero
• Basic Surface Pressure (PS-371)
– Justification:
Recreation of surface pressure distribution increases confidence in computational tools.
– Implementation:
Pressure ports are located to enable reconstruction of pressure distribution.
Engineering Impact:
First in-situ model validation of flight aero tools will lead to better uncertainty quantification and
margin clarity for future Mars entry missions.
windside
leeside
A
22 March 2007
A
16
MEDLI Objectives: Atmosphere and Aero (cont)
• Dynamic Pressure and Mach Number (PS-374 & PS-375)
– Justification:
Uncertainties in atmospheric density are co-mingled with uncertainties in aero.
– Implementation:
Two of the seven pressure ports in the stagnation region.
• Angle of Attack and Angle of Sideslip (PS-372 & PS-373)
– Justification:
For a given density, accurate measurement of angle of attack and sideslip will allow
comparison between predicted and realized aerodynamics.
– Implementation:
Five of the seven pressure ports centered about the cone apex.
Engineering Impact
• Atmospheric density quantification for assessment of aerodynamics uncertainties.
• Identification of wind component within vehicle performance (a la MER).
22 March 2007
17
Technical Status
22 March 2007
18
MEDLI - MSL Interface Overview
Descent Stage
Backshell
DPAM-B
REU Telemetry Bus
+28V Pwr
DS/BS CUTTER
4 wire Serial Bus interface
BS/HS CUTTER (NEW)
Comm
Pwr
MUX
Heatshield
Sensor Support Electronics
Recession
Sensor
MISP: X7
22 March 2007
4 Thermocouples
per plug
Pressure
Transducer
MEADS: X7
19
MEDLI Subsystem Designs
• MEADS Design
22 March 2007
20
MEDLI Subsystem Designs (Continued)
• MISP Design
TC cross-section
(only 2 TCs shown)
20.32 mm
(0.800 in)
HEAT cross-section
33.02 mm
(1.300 in)
TC wires
HEAT
Alumina tube
MISP potted to
counter sink with
GX6300
Composite
face sheet
Wire insulation
22.86 mm
(0.900 in) thick
SLA561V
Honeycomb
structure
Composite
face sheet
22 March 2007
Leads are 250 mm (~10.0 in) long. After
inserting through structure and potting, they are
trimmed, crimped to an appropriate TC or
copper pin and inserted into a connector
Through holes for
an individual lead
or a pair of leads
21
MEDLI Subsystem Designs (Continued)
2 Electronics Boards
305mm x 159mm
(12” x 6.25”)
• SSE Design
6x #10
Fasteners
6x Inserts
22 March 2007
Top Removed
for Clarity
6x Standoffs
Aluminum Honeycomb Core
TPS
Composite
facesheet
Enclosure
337mm x 248mm
(13.25” x 9.75”)
22
Changes to Baseline MSL Accommodation
• Analog to Digital Interface Change
– Benefits both MSL and MEDLI
• Reduced Aeroshell Mass Impact
• Higher quality data (better signal to
noise)
• Mass Allocation Shift
– Needed to accommodate additional SSE
functions to support digital interface
New Mass Allocation:
Cruise Stage
– Original: (15 kg Total)
• 5 kg aeroshell mass impact
• 10 kg on heatshield, offset by removing
ballast mass
– New: (15 kg Total)
• 2.5 kg aeroshell mass impact
• 12.5 kg on heatshield, offset by
removing ballast mass
22 March 2007
2.5 kg
Backshell
Descent Stage
Rover
Heatshield
12.5 kg
MSL (For Reference)
23
MSL to MEDLI Resource Allocation Status
Resource
Limit
CBE
Margin
Heatshield Mass (Kg)
12.5
9.93
26%
Backshell and Descent Stage Mass (Kg)
2.5
1.79
40%
Power (EDL Phase) (W)
30
14
114%
Data (MB)
1.5
1.13
32%
22 March 2007
24
MEDLI Technical Milestones
MEADS Arc Jet Testing
– SRR Completed
– Level 2 Requirements Baselined & Level 4
Requirements in signature process
Before Test
• Summary of Technical Milestones
– Arc Jet Tests for MEADS development
• Phase I Completed, Phase II in Progress
• ICD TIM Completed
• Analog/Digital Trade Study Completed:
Digital Selected
• Mechanical and Thermal Draft ICD (3/2007)
After Test
– Interface Development
– Transducer Procurement (3/2007), Delivery (10/2007)
– SSE Engineering Unit Delivery (5/2007)
– Environmental Qualification (12/2007)
– Flight System Delivery (4/2008)
22 March 2007
Close Up
– SLA and Coupon Delivery (8/2007)
25
MEDLI Project Organization
Science Mission Directorate
Doug McCuistion (HQ)
Mark Dahl (HQ)
Michael Myers (HQ)
Mars Program Manager
Fuk Li (JPL)
Exploration System Mission Directorate
Jeff Volosin (HQ)
Principal Investigator
PI: Neil Cheatwood (LaRC)
Deputy PI: Mike Wright (ARC)
Science Team Co-Is
Aerothermal: Mike Wright (ARC)
TPS: Bernie Laub (ARC)
Aerodynamics: Walt Engelund (LaRC)
GNC: Chris Cerimele (JSC)
MSL Project Manager
Richard Cook (JPL)
Project Management
PM: Alan Little (LaRC)
DPM: Helen Hwang (ARC)
DPM: Mike Gazarik (LaRC)
CE: Jeff Herath (LaRC)
Schedule: Cameron Pyle (LaRC)
Resources: Kathy Ferrare (LaRC)
MSL Project Office
Mission Manager
Mike Watkins (JPL)
Safety & Mission Assurance
Cindi Kingery (JPL)
Howard Tucker (LM)
MSL Flight System Accomodation
Arbi Karapetian (JPL)
MSL Aeroshell
Christine Szalai (JPL)
Pam Hoffman (JPL)
Tony Agajanian (JPL)
Eric Slimko (JPL)
Rich Hund (LM)
Ground Systems
Johnny Fu (ARC)
22 March 2007
Safety & Mission Assurance
Ray Heineman (LaRC)
Robert Burney (ARC)
MISP Subsystem
Steve Kihara (ARC)
MEADS/SSE Subsystem
Frank Novak (LaRC)
Qualification
Ed Martinez (ARC)
Environmental Test
Rick Jones (LaRC)
Mission Operations
Jeff Herath (LaRC)
26