22 March 2007 1

MSL Entry, Descent, and Landing

Instrumentation (MEDLI)

Programmatic ReviewNeil 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 2

Project Formulation Overview

22 March 2007 3

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 4

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 5

System Overview

MEDLI Chief Engineer

Jeff Herath (LaRC)

22 March 2007 6

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

Recession Sensors

Pressure Sensors

22 March 2007 7

MEDLI Active: Atmospheric Interface t-10min

MEDLI Operations Concept During MSL EDL

MEDLI Inactive: Atmospheric Interface t+4min

MSL EDL Outline

MEDLI Data Transmitted

MEDLI is taking data and MSL is storing the data in the Rover for transmission after landing

22 March 2007 8

MEDLI System Description

• MEDLI consists of 7 pressure ports and 7 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.

Cruise Stage

Backshell

Descent Stage

Rover

Heatshield

Cruise Stage

Backshell

Descent Stage

Rover

Heatshield

MSL (For Reference)

Sensor SupportElectronics

DPAM

Rover

Descent Stage

Heatshield

Backshell

cutter

Power

cutter

cutter

1553 Bus

RS422 Serial

RCE-B

28v Power

Heatshield Sensors

RCE-A

RS422 Serial

22 March 2007 9

Hollow kapton tube

Wound resistive wire

Outer kapton layer (tube or coating)

MEDLI Consists of Three Main Subsystems

• MEDLI Instrumented Sensor Plug (MISP)

– A plug consists of 1.3” diameter heatshield Thermal Protection System (TPS) core with embedded thermocouples and recession sensors

– Each plug consists of 1 recession sensor and 4 thermocouple sensors

• Mars Entry Atmospheric Data System (MEADS)

– Series of through-holes, or ports, in TPS that connect via tubing to pressure transducers

• Sensor Support Electronics (SSE)

– Electronics box that conditions sensor signals and provides power to MISP and MEADS

Thermocouple Plug Recession Sensor

Mars Entry Atmospheric Data System

Sensor Support Electronics

22 March 2007 10

MEDLI on Heatshield w/ Backshell & Rover

SSEMISP (1 of 7 Plugs) MEADS (1 of 7 Ports)

Rover

22 March 2007 11

Science Objectives

22 March 2007 12

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.

Aerodynamics & Atmospheric

– Determine density profile over large horizontal distance

– Determine wind component – Separate aero from atmosphere– Confirm aero at high angles of attack

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 13

Aerothermal/TPS Objectives

Aerodynamics/Atmosphere Objectives

P1 P2 P3 P4 P5 P6 P7371 Basic Surface Pressure X X X X X X X

372 Angle of Attack X X X X X

373 Angle of Sideslip X X X

374 Dynamic Pressure X X

375 Mach Number X X

LocationReq ID Technical Objectives

MEDLI Measurements:Sensor Placement Strategy

T1 T2 T3 T4 T5 T6 T7363a Basic Aeroheating X X X X X X X

363b Stagnation Point Heating X X

364 Turbulent Leeside Heating X X X X X

365 TPS Recession Rate X X X X X X

366 Windside Heating Augmentation X X

367 TPS Total Recession X X X X X X

368 Subsurface Material Response X X X X X X X

369 Turbulent Transition X X X X

Req ID

LocationTechnical Objectives

22 March 2007 14

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)

– JustificationTransition 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 15

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 in-depth 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 16

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 A

22 March 2007 17

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 18

Technical Status

22 March 2007 19

MEDLI - MSL Interface Overview

+28V Pwr

Pressure Transducer4 Thermocouples

per plugMISP: X7

Sensor Support Electronics

Descent Stage

Heatshield

DPAM-B

BS/HS CUTTER (NEW)

DS/BS CUTTER

Backshell

4 wire Serial Bus interface

Pwr

Signal

ConditioningSignalConditioning

RecessionSensor

MUX

MEADS: X7

REU Telemetry Bus

Comm

22 March 2007 20

MEDLI Subsystem Designs

• MEADS Design

22 March 2007 21

MEDLI Subsystem Designs (Continued)

• MISP Design

22 March 2007 22

MEDLI Subsystem Designs (Continued)

• SSE Design Top Removed for Clarity

2 Electronics Boards 305mm x 159mm (12” x 6.25”)

6x Inserts TPS

6x #10 Fasteners

6x Standoffs

Aluminum Honeycomb Core

Composite facesheet

Enclosure 337mm x 248mm (13.25” x 9.75”)

22 March 2007 23

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

– 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

Cruise Stage

Backshell

Descent Stage

Rover

Heatshield

Cruise Stage

Backshell

Descent Stage

Rover

Heatshield

MSL (For Reference)

New Mass Allocation:

2.5 kg

12.5 kg

22 March 2007 24

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 25

MEDLI Technical Milestones

• Summary of Technical Milestones

– SRR Completed

– Level 2 Requirements Baselined & Level 4 Requirements in signature process

– Arc Jet Tests for MEADS development

• Phase I Completed, Phase II in Progress

– Interface Development

• ICD TIM Completed

• Analog/Digital Trade Study Completed: Digital Selected

• Mechanical and Thermal Draft ICD (3/2007)

– Transducer Procurement (3/2007), Delivery (10/2007)

– SSE Engineering Unit Delivery (5/2007)

– SLA and Coupon Delivery (8/2007)

– Environmental Qualification (12/2007)

– Flight System Delivery (4/2008)

Be

fore

Te

st

Aft

er

Te

st

Clo

se

Up

MEADS Arc Jet Testing

22 March 2007 26

MEDLI Project Organization

Exploration System Mission DirectorateJeff Volosin (HQ)

Principal InvestigatorPI: Neil Cheatwood (LaRC)

Deputy PI: Mike Wright (ARC)

Project ManagementPM: Alan Little (LaRC)

DPM: Helen Hwang (ARC)DPM: Mike Gazarik (LaRC)

CE: Jeff Herath (LaRC)Schedule: Cameron Pyle (LaRC)Resources: Kathy Ferrare (LaRC)

MEADS/SSE SubsystemFrank Novak (LaRC)

Mission OperationsJeff Herath (LaRC)

MISP SubsystemSteve Kihara (ARC)

Ground SystemsJohnny Fu (ARC)

Environmental TestRick Jones (LaRC)

MSL Project OfficeMission Manager

Mike Watkins (JPL)

MSL Flight System AccomodationArbi Karapetian (JPL)

MSL AeroshellChristine Szalai (JPL)Pam Hoffman (JPL)

Tony Agajanian (JPL)Eric Slimko (JPL)Rich Hund (LM)

QualificationEd Martinez (ARC)

Safety & Mission AssuranceRay Heineman (LaRC)Robert Burney (ARC)

Science Team Co-IsAerothermal: Mike Wright (ARC)

TPS: Bernie Laub (ARC)Aerodynamics: Walt Engelund (LaRC)

GNC: Chris Cerimele (JSC)

MSL Project ManagerRichard Cook (JPL)

Mars Program ManagerFuk Li (JPL)

Science Mission DirectorateDoug McCuistion (HQ)

Mark Dahl (HQ)Michael Myers (HQ)

Safety & Mission Assurance Cindi Kingery (JPL)Howard Tucker (LM)