How Do You Qualify Heat
Shields on Earth?
April 14, 1982
Space Shuttle Columbia STS-003
Kuiper Airborne Observatory
Infra-Red image
Or:
Electric Arc Jet Testing at
NASA Ames
1998
Ames IHF arc jet facility
Ablating disk with bow shock
INITIALS-2
CSC/SETI Institute Colloquium Series
December 2004
Meridiani Planum
Mars Exploration Rover Opportunity
Heat shield and impact site
July 29, 2009
John Balboni
Thermo-Physics Facilities
NASA Ames Research Center
INITIALS-3
Heat Shields: Impact on Science
Heat Shield: ~10% of landed mass
820 kg (rover, lander, heatshield, parachute)
~$820,000,000 for two Mars Rovers
(APPROXIMATE)
~$500,000 per kg landed mass (two rovers)
(APPROXIMATE)
two Heat Shields cost ~$80,000,000
(APPROXIMATE)
INITIALS-4
Galileo Jupiter Probe: 1995
Galileo entry probe was 45% heat shield: 150 kg “dead” wt.
Mass
Mass
Mass
Science payload
mass is inversely
proportional to
the “delivery” mass,
including the heat shield
INITIALS-5
Columbia STS-107: April 1, 2003
Heat shield failure may lead to
complete failure of the mission and
loss of the spacecraft
INITIALS-6
Rationale for Arc Jet Testing
• R&D: provide critical data for the research and development of thermal
protection (TPS) materials
PAET
NASP
SHARP B1 & B2
X-33
FALCON/CAV
X-37
• Flight Qualification/Sustaining Engineering: qualify/certify TPS
materials and processes for National Programs
APOLLO
SPACE SHUTTLE
Orion
VIKING
GALILEO
MARS
PATHFINDER
MER
PIONEER-VENUS
MAGELLAN
STARDUST
PHOENIX
• Instrumentation: Develop surface and in-depth instruments and sensors
• Space Ops: Support TPS damage assessment and
verification of repair techniques for crewed spacecraft
Space Shuttle
Tile Damage
INITIALS-7
Acknowledgements
Contributions and charts provided by:
Dr. Michael Wright, NASA Ames
Dr. George Raiche, NASA Ames
Dr. Bernie Laub, NASA Ames
Ernest Fretter, NASA Ames
Bonnie James, NASA Marshall Space Flight Center
INITIALS-8
Summary:
The Problem (and Solution)
The Analyses
The Experiments
The Facilities
INITIALS-9
The Problem (and Solution)
INITIALS-10
The Solution: Blunt Bodies_2
INITIALS-11
Stardust Mission: Video
(play video here)
INITIALS-12
The Root Problem: Speed
Physics dictates high speeds for space travel. Consider
circular orbits at 1.025 x Radius:
Satellite Speed
Mars . . . . . . . . 3.5 km/sec
Venus . . . . . . . 7.2 km/sec
Earth . . . . . . . . 7.8 km/sec
Jupiter . . . . . . 41.7 km/sec
Escape Speed
5.0 km/sec
10.3 km/sec
11.2 km/sec
59.5 km/sec
Kinetic Energy ~ mV2
Surface Convective Heat Transfer Rate ~ V3
INITIALS-13
The Solution: Blunt Bodies
INITIALS-14
The Solution: Blunt Bodies
INITIALS-15
The Solution: Blunt Bodies
INITIALS-16
The Solution: Blunt Bodies
MSL = Mars Science Laboratory (rover); 2011 Launch
INITIALS-17
The Space Shuttle: Thermal Protection
AIM-22 Tile
AFRSI Blanket
TUFI/AETB Tile
Gap Fillers
FRCI-12 Tile
RCG Coating
INITIALS-18
The Analyses
INITIALS-19
Hypersonic Flight: Analysis
INITIALS-20
Hypersonic Flight: Analysis
CFD = Computational Fluid Dynamics
INITIALS-21
Hypersonic Flight: Analysis
INITIALS-22
Hypersonic Flight: Analysis
Except for Space Shuttle, all past Earth entry vehicles and all
planetary entry vehicles use “Ablative” heat shield materials.
TPS = Thermal Protection Sysetm (Heat Shield)
INITIALS-23
Ablative Heat Shield: Physics
INITIALS-24
Ablative Heat Shield: Physics
INITIALS-25
The Experiments
INITIALS-26
Arc Jet Test Objective
Verify on the ground the heat shield integrity before atmospheric entry
Example:
Develop and characterize material properties
Screen candidate materials
Verify heat shield design: gaps, attachments
Develop and characterize instrumentation
Verify heat shield repair techniques
INITIALS-27
Arcjet Diagnostics and Analysis:
Flight Traceability example
Aerothermal analysis predicts
the flight environment
Arc Jet flow analysis determines
appropriate arc jet test configuration
and in-depth material response
and 3 TIRS rockets with covers
were added at a late date
in 3D with chemically reactions
in the flow and at the surface
CFD solution of TIRS cover and
backshell TPS arc jet test in PTF
Arc jet diagnostics measure the
free-stream conditions and
material response
Comparing experimental and
modeling data confirms arcjet-toflight correspondence
TPS is sized to the aerothermal
environment; Final arc jet tests
establish TPS flight certification
Entry vehicle shape is established,
MER
aeroshell
Calibration Data and Pre-Test Predictions
Heat Flux, W/cm
2
Calibration Data
CFD
10
1
0.1
0.0
Photo of TIRS arc jet test in PTF
0.1
0.2
0.3
X, m
0.4
0.5
0.6
MER TIRS flight article
INITIALS-28
Space Shuttle Wing Leading Edge Repair
Pre-test:
9x9 inch
panel with
7’’ plug
repair
15 min. arc-jet
test; exceeding
2000 C on the
material
INITIALS-29
The Facilities
INITIALS-30
Arc Jet Complex
STATUS: Operational (Commissioned 1962)
LOCATIONS: N-234 and N238
Four Arc-Jet Facilities:
• Aerodynamic Heating Facility (20
MW)
• 2-By- 9-Inch Supersonic Turbulent
Flow Duct (20 MW)
• Panel Test Facility (20 MW)
• Interaction Heating Facility (60 MW)
One of only three such facilities in the US;
(Two NASA, One DoD)
INITIALS-31
Arc Jet Panel Test
Panel test in
semi-elliptical
flow nozzle;
side view;
80 cm x 80 cm
Flow
IR image of tile panel;
Top view
INITIALS-32
Arc Jet Schematic
Objective: Simulate entry heating in a ground-test facility
Goal: Verify a thermal protection material/system design before flight; support continuing
engineering during operations
ARC HEATER
NOZZLE
TEST CHAMBER
High Energy Flow
Mach 5 - 7 at exit
10-45 MJ/kg
Gas Temp.
> 8,000 K
Vacuum Test Chamber
Simulates altitudes 30–60 km
Method: Heat a test gas (air) to plasma temperatures by an electric arc,
then accelerate into a vacuum chamber and onto a stationary test
article
Ames High Enthalpy Test Facilities
Aerodynamic
Heating Facility
Interaction Heating
Facility
20 MW - TPS Free
Jet Testing
60 MW - TPS Free Jet and
Panel Testing
Panel Test Facility
20 MW - TPS Panel Testing
2”x9” Turbulent Flow Duct
20 MW - TPS Panel Testing
INITIALS-34
Arc Jet Test Crew
Arc Jet
Jet Photo
Test Samples
Arc
Arc Jet Walk-Around
(play video here)
Arc Jet Test
(play video here)
Future Human Exploration
INITIALS-39
Scenario: Lunar Exploration
All lunar sorties require Earth return entry vehicle:
EXAMPLE ONLY
Reference ESAS Requirements Study, June 1, 2005
INITIALS-40
Candidate CEV Configuration
Ames is positioning itself for a major role in TPS design
Reference ESAS Requirements Study, June 1, 2005
INITIALS-41
Summary - Conclusion
INITIALS-42