Planetary Probes:When it Has to be In-Situ

Anthony ColapreteNASA Ames Research Center

10th Annual International Planetary Probe WorkshopJune 17, 2013

Planetary Probes:When Less is More

What is a Planetary Probe?

Planetary “probes” come in all shapes and sizes:• Atmospheric entry probes, landers, rovers, orbiters, balloons, airplanes• Common feature: in-situ

Some questions required measurements that are in-situ• Potentially limiting the total data and/or the “breadth” of observation• Often very complex (read: “expensive”) to get “a lot” on an in-situ probe

They have to compete with a perception that more is better• A missions duration or number of terabytes often used as measure of intrinsic

value• Sometimes more data is better, e.g., increasing SNR, more complete spatial or

temporal coverage, etc.• All against a backdrop of dwindling opportunities and resources

Examples of when in-situ measurements are unique and critical

Atmospheres• Concentrations of key species, e.g., Nobel gasses• Ratios of stable isotopes, e.g., those in the Martian (MAVEN and

Curiosity), Venus, Titan and in the Saturn atmosphere• Dynamics, e.g, atmospheric structure, stability and winds in the Venus,

Mars, Titan and Saturn

Surface and Subsurface• Specific elemental composition at small scales• Soil/regolith processing for composition or other parameter• Micro-scale morphologies• Sub-surface access; volatiles, environment (thermal state)• Geophysical parameters: seismometery and geotechnical measures

How do we adapt our thinking of planetary probes to changing resource profiles?

To be acceptable (i.e., selected) in-situ probes must align with:

• Be more affordable – Both monetarily and in terms of engineering metrics (mass, power, etc.)

• Use new techniques, designs, and architectures – Make them applicable to a range of parent architectures; take advantage of multitude of launch opportunities

• Unique and critical measurements – Worth the headache of not making the measurement remotely

From D. Bearden, The Aerospace Corporation

KISSKeep the Science Focused

Once the focused goals are set….stay disciplined!

The key science objectives that would be addressed by a Saturn Probe mission include:

– Origin and Evolution – Saturn atmospheric elemental ratios relative to hydrogen (C, S, N, O, He, Ne, Ar, Kr, Xe) and key isotopic ratios (e.g., D/H, 15N/14N, 3He/4He and other noble gas isotopes), He relative to solar, Jupiter.

– Planetary Processes – Global circulation, dynamics, meteorology. Winds (Doppler and cloud track), interior processes (by measuring disequilibrium species, such as PH3, CO, AsH3, GeH4, SiH4). [P, C]Ref: Atreya, S. K. et al., (2006) Multiprobe exploration of the giant planets – Shallow probes, Proc. International Planetary Probes Workshop, Anavyssos, 2006.

Ref: David Atkinson

NASA – Cassini: PIA03560: A Gallery of Views of Saturn's Deep Clouds

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An example of how focusing the science can “enable” a probe mission: Saturn Probes

Probe Size and Data Rate Drive Architecture

Data Telecom

Antenna Size and Type

# and Type of Instruments

A high-level view to illustrate how two key parameters drive design to the same conclusion

Descent vs Com. Power

Size Mass

LV

Cost

# of ProbesGalileo-Type

Probes8

An alternate Architecture would start with the most focused payload possible

For example, to address the critical questions regarding composition, the most important instruments are:• Neutral Mass Spectrometer (NMS) or Gas Chromatograph Mass Spectrometer (GCMS)• Atmosphere Structure Instrument (ASI)

Accepting just these two measurement/instrument types would approximately halve the data, mass, and power requirements of the payload• This assumes no improvements over Galileo instrumentation, which is an incorrect assumption• Significant savings can be realized in reduced mass instrumentation, in particular in the area of the

NMS/GCMS

The lower mass, power and data rate can result in a smaller probe• Assuming a payload mass fraction of approximately 10% the probe mass, a 100-150 kg probe is a

reasonable goal

Alternate Architectures

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Example of Alternate Architecture Trade Space

Focused Payload

Probe Size/Mass

Instruments on Probe and Probelet

Relay Options

Descent Depth

Probelet Drop Depth

Wind Shear

Frequency vs Antenna Reqs.

Look Angles

Water Constraint

Data Rate

Structure Measurements

A fresh look, beginning with a highly focused measurement set, greatly opens otherwise closed trade space

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JPL cubesat transponder

LMRST antenna

NanoSpace MEMS propulsion module

Aerojet 1U Champs

MIT Space Propulsion Lab/Paulo Lozano

Cubesat reaction wheels(Sinclair Interplanetary)

NLAS 6U dispenser

Shrinking the Probe: Technologies looking for a home?

• While we can build all sorts of nano-scale probes, are they capable enough to address important questions in a meaningful way?

• Strengths in their small “footprint”: more opportunities to fly more payloads more often

• Need to take care to align with the “Unique and critical science”

MicroProbe Examples

Microprobes defined here as 10-100 kg• Include cubesat technologies and architectures

Concepts floating about include entry vehicles, aero-platforms, landers, rovers, spacecraft (orbiting, flyby, or rendezvous, comm-relay)

Payload mass typically 1-10 kg• Sufficient to include instrument capable of of critical

measurement(s)

Newer technologies allow for very capable propulsion

These Microprobes have the potential to extend deep-space access to low-cost research

One example is the Planetary Hitch Hiker (PHH), a low-cost rideshare platform for exploring Near-Earth Asteroids (NEAs)

Initial mW GeneratorFits at the core of the Baseline Science Station

Cubesat Compatible Spine(Science Station Baseline)

• Small entry probes have potential to open up a new means of exploring Mars, Venus, and other planetary bodies with atmospheres

• With small payloads entry probes can be scaled down considerably (2x-3x scaling)

• In the low end of the Microprobe size class (~10 kg) with half the mass being for the payload

Micro-Entry Probes Examples

From Marc Murbach

For Example: Mars MET Stations

Commercial Partnerships, COTS Products, and Secondaries

Increased commercial access to space is accelerating commercial product lines, everything from components to complete spacecraft

Many smaller commercial companies eager to work with NASA or other agencies and larger business to provide or develop instruments, components and systems

A few examples:• Using commercial product line, partnered with NASA to

develop a flight version: LCROSS Ultraviolet spectrometer done in <9 months RESOLVE NIR spectrometer, done in <1 year

One of the largest financial commitments is the launch vehicle• Every kg of lift capacity should be taken advantage of• Opportunities for micro-probes

Spectrometer

LimbTelescope

SolarViewer

LADEE UVS

Closing Thoughts

Past Probe Missions:• 1978 (PV), 1995 (GL), 2000(DS2), 2004(HUY)• With this trend might have expected the next probe

mission in ~2012

But what opportunities?• Decadal Survey called out Venus and Saturn Probe

missions• Numerous Discovery class concepts• Very competitive, risk adverse

Need to be ready with Strong Concepts and New Ideas:• Starts with focus, unique science goals

Minimize complexity• Take advantage of smaller systems and components• Build commercial / government alliances• A secondary on every launch!

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Thank you!