Brian Lewis

Systems Engineer

NASA Ames Research Center

BioSentinel: Monitoring DNA Damage

Beyond Low Earth Orbit on

a 6U Nanosatellite

BioSentinel

Mission Goals and Objectives

• Conduct life science studies relevant to human exploration – 1st biological study beyond LEO in over 40 years

– BioSentinel uses DNA double strand break frequencies to calibrate radiation damage in space

– Validate biological radiation damage models in space

– Demonstrate “biosentinel” science concept

• Design payload with sensors for multiple environments – BioSensor, LET Spectrometer, TID Dosimeter

– Secondary payload on Space Launch System (SLS) EM-1 in late 2017

– Instrument on ISS at similar time to EM-1 launch

– Ground controls in lab and at radiation beam facilities

2

BioSentinel

• Quantify DNA damage from space radiation environment – Space environment cannot be reproduced on earth

– Omnidirectional, continuous, low flux with varying particle types

– Health risk for humans spending long durations beyond LEO

– Radiation flux can spike 1000x during a solar particle event (SPE)

• Correlate biologic response with TID and LET data – BioSensor payload uses engineered S. cerevisiae

– Measures rate of double strand breaks (DSBs) in DNA

– LET spectrometer measures particle energy and count

– TID dosimeter measures integrated deposited energy

• Yeast assay uses microfluidic arrays to monitor for DSBs – Three strains of S. cerevisiae, two controls and an engineered strain

– Wet and activate multiple sets of microwells over mission lifetime

– DSB and associated repair enable cell growth and division of the engineered “biosentinel” strain

– Activate reserve wells in event of an SPE

BioSentinel Science Concept

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BioSentinel

• Freeflyer launched as a secondary payload on EM-1 – Exploration Mission 1: 1st flight

of NASA’s Space Launch System

• Final orbit of secondaries to be determined

• Will likely be Earth-interior, heliocentric orbit

• Far outside the LEOs typically occupied by CubeSats

– Range to Earth of 0.73 AU at 18 months

– Far outside the protective shield of Earth’s magnetosphere

A representative orbit that BioSentinel might occupy

Launch

Artist’s rendering of the Space

Launch System

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Mission Orbit BioSentinel

Orbit

BioSentinel

5

nogamma

25Gy

50Gy

100Gy

~180Gy

nogamma

25Gy

50Gy

100Gy

~180Gy

SCmedium(viability)

SC-LEUmedium

3daysat23°C

~2x106

cells/well~2x102

cells/wellNocells

Payloads and Data Products

LET Spectrometer Chip

Teledyne dosimeter Typical LET Spectrometer Frame

Prototype Fluidic Card

• 3 color optical system per well

• Colorimetric and optical density assay

• Pressure, RH and temp sensors in payload volume

• Selective downlink of spectrometer data

• Active monitoring of LET and TID to trigger SPE response

BioSentinel

Spacecraft Design

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PharmaSat carried a microwell and fluidics system similar to that which will be used in

BioSentinel

Avionics Transponder

Payload

Deployable Solar Arrays

Propulsion System

Batteries

Star Tracker

• Extend ARC biological nanosats to 6U form factor – Port application-based LADEE flight software to capable, reliable avionics

– Support autonomous guidance, navigation, attitude control, and propulsion

– Generate sufficient power for transponder over long link distances

BioSentinel

Electrical Power • Deployable solar arrays

– 31 W generated at end of life

• 3s2p Li-Ion Battery pack – 5100 mA-hr capacity

• Required for detumble after deployment

• Required for momentum management

• Evaluating cold gas and electric propulsion systems

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Propulsion

0 50 100 150 200 250 300 350 400 450 500-8

-6

-4

-2

0

2

4

6

8

time (sec)

de

g/s

ec

Body Rates

x

y

z

Detumble controller simulation

BioSentinel

Guidance, Navigation and Control • GNC Functions

– Detumble

– Pointing for communications, power generation, and safe mode

– Autonomous momentum management

• 3 axis controlled system

– Reaction wheels and star tracker for nominal operations

– Sun sensors and inertial measurement unit for contingencies

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GN&C Development Testbed

Simulated Controller Performance 0 5 10 15 20 25 30

0

10

20

30

40

50

60

70

time (min)

err

or

(arc

se

c)

Angular Attitude Error

unfiltered

EKF

BioSentinel

Communications • X-Band Coherent Transponder

– Command and Telemetry

– Ranging and Nav Support

– 100 – 4000 bps telemetry

• 20 dB medium-gain antenna and 6 dB low gain antenna

• Deep Space Network 34m ground station

• 2 – 8 hours aperture time per week

9

0

1

2

3

4

5

6

7

8

9

100 200 300 400 500 600

Po

ssib

le D

ata

Rat

e [

kb/s

]

Mission Elapsed Time (Days)

Achievable Downlink Data Rate During Mission

6dB link margin

3dB link margin

BioSentinel

Structures / Thermal • 6U volume nanosatellite

• BioSensor payload maintained at 1 atm pressure

• Payload cold biased to 4 C for yeast viability

• Active microfluidic “tile” maintained at 23 °C for growth

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Payload Thermal Variability

Spacecraft Internal Temperatures

BioSentinel

• 1st NASA biology studies beyond LEO in 4 decades

– Enabling comparison across multiple radiation & gravitation environments

• 1st 6U CubeSat to fly beyond LEO

– Challenges for communications and attitude control

– Collaboration with sister missions reduces risk

• 1st CubeSat to combine a biology science payload with capable C&DH and FSW

– Payload includes autonomous measurement response to SPEs

BioSentinel (Potential) Firsts and Challenges

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Support : NASA Human Exploration and Operations Mission Directorate (HEOMD)

Advanced Exploration Systems Division – Jitendra Joshi, Jason Crusan Program Execs.

Affiliations : NASA ARC, NASA JSC, NASA GRC, Loma Linda U. Med. Center, Univ. Saskatchewan