miniaturization of planetary atmospheric probes tony colaprete nasa ames
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Miniaturization of Planetary Atmospheric Probes
Tony ColapreteNASA Ames
History of atmospheric entry probes and scienceWhat probes have flownWhat have they measuredWhat were their limitations
Building an entry probeSurvival First, Measure LaterTechnological (and Physical) Limitations
Changing the paradigmThe curse of Galileo - Hand-me-down scienceEnabling Sensors & TechnologyPico probes - New Architectures and Systems
“Outline”
Credits: Gary A. Allen, Jr., William H. Ailor, James O. Arnold, Vinod B. Kapoor, Daniel J. Rasky, Ethiraj Venkatapathy
History of planetary entry “probes”
Since the 1960’s:Mercury,Gemini, Apollo, Soyuz , etc. (Earth)PAET (Earth)Pioneer Venus, Vega, Venera (Venus)Viking, Pathfinder, MER, DS-2 (Mars)Galileo (Jupiter)Huygens (Titan)
Future (on the books):Phoenix Lander (Mars)Mars Science Laboratory (Mars)ExoMars – ESA (Mars)
Talked about:Venus SAGETitan Aerobot/Rover
Jupiter, Saturn & Neptune
Viking (1976)
Galileo (1995 )
Pioneer-Venus (1978)
PAET (1971), An Entry Probe Experiment in the Earth’s AtmosphereM = 62 kg, Minst = 14 Kg, Rb = .914 m
Atmospheric Science: PAET, Pioneer-Venus, Viking, Galileo and Huygens
State-of-the-Art (16 years ago): Huygens
Probe specifics:• 2.7 m diameter heat shield• Total Probe mass of 349 kg• 6 instruments (49 kg or 14%)
All In-Situ Mars Atmospheric Data…
Viking 1 & 2:• Atmospheric state variables during entry (direct). • 5 minutes each
Pathfinder and MER:• Atmospheric state variables during entry (derived).• 5 minutes each
Phoenix:• Atmospheric state variables during entry (derived).• 5 minutes
In-Situ Mars Atmosphere Profiling
In All, about 25 minutes has been spent making measurements between the surface and 80 km.
And now for the rest of the data…
T (K)100 200 300 400 500 600 700 800
z (k
m)
120110100
9080706050403020100
clou
ds
?
Venus Profile Titan Profile
And now for the rest of the data…
In all, planetary entry probes have measured ~14 individual profiles
The limitations of entry science
• Up to this point it is very costly in terms of mass, and always mass = $$
• Can only afford to fly a few (if your lucky) and usually only one - Statistics of small numbers (e.g., Galileo)
• Limited lifetime – poor temporal coverage
The challenge is to change the way probes are done to overcome these limitations!
Huygen Mission Design
Payload
Range: 5%-25%
Aeroshell (TPS)
Range: 3% - 50%
Aeroshell (strcutures)
Range: 5% - 12%
Aeroshell Parachute
Range: 2% - 5%
Power/Thermal/Com
Range: 5% - 20%
Orbit Insertion (Propulsion & Fuel)
Range: 15% - 40%
Spacecraft/Bus/ Com
Entry Probe
Range: 25% - 40%
Range: 25% - 40%
Spacecraft Mass fraction
Probe mass fraction
Cassini Spacecraft Components
Atmospheric Entry Mission & Probe Design
Mission Design Considerations:• Intended Science – Where are you headed?
• Key Factors: Mass, Volume, Power, Design Complexities (risk) and Cost
• Science payload (mass, power, etc) significantly impact both mission architecture and hardware (mass, power, complexity and cost) – Drives Probe Size
Galileo – A flight through a nuclear blast
About 50% of the probe was TPS
Jovian Entry TPS Study• Calculations by Dr. G. Allen / M. Tauber, ELORET based on Engineering Code by Tauber, et. al.
• Galileo entry conditions 48 Km/sec, - 6.64o E. angle, equatorial entry
• Carbon Phenolic TPS - TPS mass fraction is insensitive to entry probe size
• Science mass available for microprobe approx. 1 kg
Galileo: Probe Mass: 338 kg, Science Mass: 8.3% of Entry Probe massBase Radius: 1.28 m
microprobe
0.480
0.485
0.490
0.495
0.500
0.505
0.510
0.515
0
50
100
150
200
250
300
350
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Mas
s TP
S/M
ass e
ntr
y En
try mass (kg
)
Ballistic co
efficient, (kg
/m2)
Rbase
/Rbase(Galileo)
TPS mass fraction
Entry mass
Designing for Hell
The gas giants present extreme performance limits to TPS
Pascal Sample Network Configuration
Pascal – A Mars Network Mission Using Micro Probes
Pascal Probe Deployment Sequence
Pascal – A Mars Network Mission
Probe Entry System
0.5 m
Science Station
- 70° half angle cone- Hemispherical backshell- 20 kg entry mass - RHU powered
Pascal – A Mars Network Mission
Pascal Carrier S/C accommodates 24 Probes with a Delta III or IV Launch Vehicle
Stowed in D3940 Fairing
Fixed Solar Array
ADCS and Telecom Components
Power and C&DH Components
Hydrazine Thrusters
MGA’s and LGASpacecraft
Bus
Probe Dispenser Panels (4)
Pascal EDL SequencePascal EDL SequenceSelforientationSelforientation
Aft domeseparatesAft domeseparates
Parachute deployment separates
entry probe from science package
Q = 700 PaM = 1.5 – 2.2
Parachute deployment separates
entry probe from science package
Q = 700 PaM = 1.5 – 2.2
Jettison airbag andinitiate landed operations
Jettison airbag andinitiate landed operations
Airbag protects science station at impact – numerous bounces
Airbag protects science station at impact – numerous bounces
Airbag inflates immediately after chute deployment
Airbag inflates immediately after chute deployment
Entry•Speed = 6 km/s•Landing in 4 minutes
Entry•Speed = 6 km/s•Landing in 4 minutes
Chute separates after first impactChute separates after first impact
Pascal – A Mars Network Mission
Pascal requires several enabling technologies/developments
LandingSphere
Sensor Booms
Wind
Temperature
Pressure
Accelerometers
Gyroscopes
Enabling Sensors - Venus SAGE
IMU & Moutherboard
Provides information on all atmospheric state variables, stability, and winds during descent and landing.
Atmospheric Structure Investigation
2.54 cm
GSFC
1/ 2 mm.
GSFC Research thrust: one kg/one Wmass spectrograph with capability of
Cassini/Huygens technology 17 kg/ 15W
GSFC developmental time offlight mass spectrograph core 50 gm, 10 cm length
Jamieson & P. Roman/GS FC; L. Delizet,/ARC
Cassini/Huygens ion sourceThermionic electron gun
CNT based ion source undergoing evaluation
2.54 cm
GSFC
1/ 2 mm.
GSFC Research thrust: one kg/one Wmass spectrograph with capability of
Cassini/Huygens technology 17 kg/ 15W
GSFC developmental time offlight mass spectrograph core 50 gm, 10 cm length
Jamieson & P. Roman/GS FC; L. Delizet,/ARC
Cassini/Huygens ion sourceThermionic electron gun
CNT based ion source undergoing evaluation
Enabling Sensors - Amazing Shrinking Sensors
A miniaturized mass spectrometer
Modular reentry probe:• Conduct flight-testing of an integrated entry system• Flight qualification of subsystems such as TPS, innovative sensors and science instruments• Perform low cost atmospheric science experiments
Specifications:• ~ 20 cm in diameter• Total mass ~ 1 kg• Payload mass ~ 0.3 kg• Heatshield mass fraction < 7% (for Mars entry)
The Pico Reentry Probe (PREP)
Possible mission architectures
Multiple atmospheric sounders• More valuable in atmospheres where remote sensing is difficult (e.g., thick or opaque)• …or for measurements that are difficult to make with remote sensing (e.g., methane on Mars, water in Jupiter)• “Ground” truth for remote sensing (e.g., winds, composition, state)
Landed Network• Hard landers would retain the most simplicity• Synoptic weather• Seismic networks• Penetrator (e.g., DS-2)
Crewed Descent• Forward observers to high-value descent vehicles
Science instrument design•Multiple integrated sensors
TPS• Rethink design• New materials for outer planets
Terminal descent & landing• Parachute?• Heat shield separation• Novel Shapes?
Thermal and power management• Extreme operational ranges
Data storage, processing, relay & comm.• Miniature & ruggedized transmitters
Micro Probe System Considerations
Micro Probe System Considerations
3corner micro-satST5 micro-sat
Examples of integrated micro-systems
“A personal impression is that more can and ought to be done with simple sensors : a shift of emphasis from exquisite construction to testing and analysis.” – Ralph Lorentz
Concluding Thought
NASA V-Team Descent Probe• 4 accelerometers• 3-axis gyro• 2 external temperature• 2 external pressure• GPS• Total mass ~3kg
Existence Proof – NASA V-Team
The probe is no longer a vehicle but rather an instrument
into itself.
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