dr. ashitey trebi-ollennu technical group leader, mobility ......touch-and-go (tag) missions enable...

Overview of Key Technologies for Small Bodies “Gas, Dust, and

Surface Sampling” and Recommendations for Technology

Development Priorities for 2013-2032 Timeframe.

Dr. Ashitey Trebi-Ollennu

Technical Group Leader,

Mobility & Manipulation Group

Mobility & Robotic Systems Section

Jet Propulsion Laboratory,

California Institute of Technology

4th Meeting of the NASA Small Bodies Assessment Group

The Westin Washington National Harbor, Washington D.C.

Tuesday, January 25, 2011

Copyright 2011 California Institute of Technology.

Government sponsorship acknowledged.

1. Overview of Key Technologies for Small Bodies Sampling • Fly Through/Flyby Missions

• Touch-and-go Missions

• Landed missions

2. Recommendations for Technology Development Priorities for 2013-2032

Timeframe• Smart Sampling Systems Technologies

• In Situ Microanalytical Technologies

• Sample Verification Technologies

• Small Bodies Physics-Based Modeling and Simulation

3. Conclusion

Outline

201/25/2011Dr. Ashitey Trebi-Ollennu, 4th NASA SBAG

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Fly-through missions reduce cost by eliminating the need for direct contact by the

spacecraft with the surface, but currently they can sample only the coma of comets. The

spacecraft flies over the planet, a single time or repeatedly, at an orbit sufficiently low so

that the material sought crosses its trajectory.

1. Current-State-Of-The -Art

1. The Stardust mission brought back small particles collected from hypervelocity particle

impacts into aerogel when flying through the coma of comet 81P/Wild 2.

2. This type of mission is perfect for

1. Collecting samples of a planet’s atmosphere or a comet’s tail.

2. A variant of this mission is one that the spacecraft creates a plume of material from an

airless body by impacting a probe into the surface then the spacecraft flies through the

plume to collect samples.

3. Technology Needs

1. Fly-through missions would benefit from spacecraft flying a probe into the small body to

generate sample material, e.g. via an impactor.

Fly Through/Flyby Missions


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Touch-and-go (TAG) missions enable direct surface sampling during the brief touch

phase.

1. Current-State-Of-The –Art

1. JAXA’s Hayabusa mission attempted to acquire material ejected from the surface of

asteroid (25143) Itokawa after firing a bullet into the surface. Hayabusa demonstrated

a TAG mission scenario where the spacecraft briefly touched the asteroid for sampling.

2. This type of mission is perfect for1. Collecting surface samples from comets, asteroids or small moons, where the gravity

force is negligible.

2. Collecting surface samples from extreme planetary environments where spacecraft

exposure to the environment needs to be minimized.

3. Technology Needs1. Smart deployment mechanism designs to reduce severe and unpredictable forces and

torques experience by the spacecraft during the touch phase.

2. Sampling tool deployment mechanisms

1. Via ejector darts

2. Explosives

3. Subsurface Sampling tools

Touch-and-Go (TAG) Missions


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Touch-and-Go (TAG) Missions

JPL TAG Sampling Tool Brush Wheel Sampler

Video of brush wheel sampler

Sample Acquisition

• Flight-like shaped canister

• 60° off alignment to 30° slope

• 50-80 kPa mixed pumice

• 0.5 kg/s collection rate

Sample Acquisition

• Flight-like shaped canister

• 30° slope

• 6 cm/sec horizontal velocity

• Glass bead simulant

• 0.22 kg/sec collection rate


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Sample Acquisition

• Vaccum Chamber

• Glass bead simulant

• 0.22 kg/sec collection rate

Landed missions enable careful investigation of surface and subsurface samples but are

more costly due to the added complexity of landing and adhering to the surface in the

microgravity environment.

1. Current-State-Of-The –Art

1. Rosetta SD2 sampling system represents the state of the art in sampling to depth in

comets.

2. This type of mission is perfect for

1. Collecting surface and subsurface samples from planets, comets, asteroids or small

moons.

3. Technology Needs

1. Smart deployment mechanism designs to reduce sample tools preload requirements.

2. Sampling tools for sampling at depths of 1m or more.

Landed Missions

01/25/2011 6Dr. Ashitey Trebi-Ollennu, 4th NASA SBAG

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1. Robust systems for sample acquisition, handling and processing are critical to the

next generation of robotic explorers for investigation of planetary bodies.

2. Future missions will need to acquire surface and subsurface samples from comets,

asteroids, and small satellites such as Phobos and Deimos.

3. The breadth of technology challenges associated with sample acquisition for in situ

analytical surface exploration missions and sample return missions would severely

challenge the current state-of-the-art technology.

4. In addition, limited spacecraft resources (power, volume, mass, computational

capabilities, and telemetry bandwidth) demand innovative miniaturization and

advanced component design for integrated sampling systems that can survive and

operate in challenging environments (extremes in temperature, pressure, gravity,

vibration and thermal cycling).

5. NASA has very limited experience in planetary and small bodies sample

acquisition, in particular, astrobiological and subsurface volatiles (ice phase)

samples. For example on Mars, the experience is limited to Viking and Phoenix

scoops for sampling regolith.

Technology Development Priorities for 2013-2032


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1. In general technology development timescales are long, so it will be most productive to

align technology development strategy on the expected general characteristics of

future missions.

2. We propose an aggressive and focused technology development strategy that aligns

with the following potential recommended mission profiles

1. Comet Surface Sample Return (CSSR) Mission (sample size 250 cc to380 cc)

2. Cryogenic Comet Nucleus Sample Return (CNSR) Mission (core at least 25 cm

deep and 3 cm across )(2021–2030)

3. Key Technologies

1. Cryogenic sample acquisition

2. Cryogenic sample handling (sample distribution/interrogation systems)



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Smart Sampling Systems Technologies for preserving sample integrity

1. Development of smart surface and subsurface acquisition tools that preserves the

integrity of the sample cores resulting in an increase in science return.

1. The scientific conclusions of missions that need to acquire surface and subsurface

samples depend on knowing why and how samples may be chemically altered during

collection or processing.

2. There is a need for significant improvement in preserving the integrity of subsurface

sample cores from initial acquisition to the end of the sampling handling chain.

3. There are several loss mechanisms that can chemically alter acquired samples. For

example, the ice content of samples taken on Mars can undergo “passive” sublimation

after the desiccated outer layer is removed to expose the permafrost substrate, and

“active” sublimation during tool interactions, followed by passive sublimation during

sample transfer, prior to analysis.

4. To ensure the validity of H2O composition measured in the icy sample all loss

mechanisms must be considered. There is currently no tool for capturing and measuring

these types of transient compositional or morphological altering events in situ during

sample acquisition and transfer chain.



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In Situ Microanalytical Technologies

1. Development of in situ microanalytical technology that will enable transient

compositional or morphological altering events to be captured and detected in situ

during sample acquisition and transfer chain.

1. Another challenge is the lack of sufficiently sophisticated down-hole in situ analyses

technology as a result core samples must be transported to the surface for analyses.

Such surface analyses lead to additional technology and engineering issues that must be

addressed these include: the method of transporting and storage of excavated materials

to the surface; containment of sample during transport to surface; development of a

logging system; and sample analysis at the surface.

2. Microanalytical techniques should be applied in situ to identify physical textures and

surface chemical signatures of rocks, soils and ices.

3. Microanalytical characterization of sample spatial variability as a function of depth or

mineralogy



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Sample Verification Technologies

1. Development of in situ Sample Quantity Verification Technologies

1. There is a technology gap for sample acquisition verification systems for robotic sample

return missions.

2. A key mission success criterion for robotic sample return missions is that an assured

sample quantity (mass/volume ) has been collected before the return to Earth phase of

the mission is initiated.

3. For some robotic sample return missions sample acquisition verification must be done

autonomously without ground operations.

4. NASA's Genesis and Stardust robotic sample return missions successfully returned

samples to Earth without an in situ sample acquisition verification system on board the

spacecraft. Positive confirmation of successful sample acquisition and transfer was done

after the return of the sample capsule to Earth. These two missions are an exception

because of the types of sample they acquired, no direct interaction with the target body

was required and sample acquisition time was in order of several minutes.



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Sample Verification Technologies

1. Development of in situ Sample Content Verification Technologies

1. Sample elemental /mineralogical composition e.g. verify that sample contains at least

20% ice



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ASTEROID Brush Wheel

Sampler


Physics-Based Modeling and Simulation for Small Bodies Sampling

1. Provides a rapid and realistic test and design environment for comet stimulant

material, vacuum, low temperature and low gravity for testing and verifying

sampling concepts

1. TESTBEDS (- replicated easily, physics low/zero-g, hybrid testbeds, virtual field test, ops training)

2. ANALYSIS(- mechanisms, mobility, lighting, surface response, particles, parametrics, con-ops)

3. DESIGN( combined RCS, momentum wheel, leg systems, low-g systems, contact mechanisms, tethering systems, novel ideas, collaborative designs, evolutionary design)

4. BUILD & OPERATE ( V&V, visualize, maneuvers, targeting)


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Key Features

• Side-canister 3-wheel

• Average of 0.71 kg/s with a

variety of test simulants (glass

beads, Bandelier tuff with 1 cm

rocks, fine and coarse pumice,

talcum, 4 mm styrofoam peanuts)

• Test conditions (slopes up to 30 ,

6 cm/sec horizontal velocity)

• Sampler model integrated into

physics-based simulation with

thrusters and robot arm

Robot arm sampling device interactions with

during touch-and-go sampling operation

Attitude control profiles

ASTEROID Brush Wheel

Sampler

JPL Robotics

Physics-Based Modeling and Simulation of Contact/Sampling



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Key Features• Mass: 4.35 kg

• Dimensions: 350 mm

diameter x 440 mm high

(extended)

• Maximum Hopping Velocity:

2.63 m/s

• Range of Hopping Pitch

Angle (from horizontal): 50º-

90º

• Range of Hopping Direction:

Full 360º

• Capability in 10 μG

environment:35 m vertical

hop/; 69 m horizontal hop for

50 hop angle

Steering

actuators

Spring-loaded

legs for

hopping

Internal

gyro for

stability

Platform body for

science payload

and controls

The hopping robot can hop at various angles with adjustable strengths to

achieve a desired vertical height or horizontal distance.

JPL Robotics

Physics-Based Modeling and Simulation of Hopping Mobility



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Key FeaturesEnvironment

• Gravitational Acceleration: 0.0005 m/s2

• Number of Particles: 4600

• Particle sand box: 1m x 1m

• Particle shape: Randomized

dodecahedrons

• Particle radius distribution: 7mm to 10cm

• Particle mass distribution: 10g to 30kg

Hopper

• Mass: 10kg

• Height: 50cm

• Foot Size: 6cm x 12cm

• Initial velocity in x-direction: .03 m/s

• Initial velocity in y-direction: .05 m/s

Hopping robot interacts with granular material on surface of asteroid

Physics-Based Modeling and Simulation of Surface Mobility



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In Conclusion…


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1. In order to reduce development cost and risk for the potential Comet Surface

Sample Return and Cryogenic Comet Nucleus Sample Return (CNSR)

Missions we propose an aggressive and focused technology development

strategy in the following areas;

1. Cryogenic sample acquisition

1. Smart Sampling Systems Technologies for preserving sample integrity

2. Cryogenic sample handling (sample distribution/interrogation systems)

1. In Situ Microanalytical Technologies

2. Sample Verification Technologies

3. Small Bodies Physics-Based Modeling and Simulation

1. Technologies to simulate contact/sampling regolith interactions

2. Technologies that enables virtual field test, hybrid testbeds, and modeling of

comet stimulant material, vacuum, low temperature and low gravity.

2. For more information with ongoing updates see:

http://www-robotics.jpl.nasa.gov/

3. Please contact me if you would like to visit or work with us…

[email protected]

Conclusion


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Thank you. Questions?


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dr. ashitey trebi-ollennu technical group leader, mobility ......touch-and-go (tag) missions enable...

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