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Using Spitzer to Observe the Solar System

Sean Carey Spitzer Science Center

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Spitzer Space Telescope

•  NASA’s Infrared Great Observatory –  Launched on 25 August 2003 –  Solar Orbit -- Earth trailing –  85 cm telescope –  Calibrated data products provided through archive

•  Post-cryo mission started 27 July 2009 •  Operate as a general observatory through 2018

until JWST launches •  Solar system science 10% of last observing cycle •  Exoplanets 25% of warm observations •  Potentially useful in more directed science plan

for 2019-2020

Exoplanets

BrownDwarfs

Galac3cStructure

StarForma3on&DebrisDisks

YoungStellarObjectVariability

CompactObjects&EvolvedStarsDistantUniverse&Cosmology

NearbyGalaxies

GalaxyClusters

AGN/ULIRGS

SolarSystemObjects

TransientUniverse

Cycles11-12

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Solar System Programs Selected for Cycle 11

•  1033.1 hours selected (15 props, 3514.2 hrs submitted) –  Three are led by new Spitzer PIs

PID ScienceCategory Hours PI Ins4tu4on

11002 NEOs 710.1 DavidTrilling NAUAnExplora+onScienceSurveyofNearEarthObjectProper+es

11106 Comets 237.6 MichaelKelley MarylandCO2OrbitalTrendsinComets

11097 Asteroids 50.0 BenRozi3s TennesseeThermalEmissionLight-CurvesofRapidlyRota+ngAsteroids

11145 Asteroids 22.2 EricMacLennan TennesseeRegolithSizeSor+ngonQ-typeNEAs

11090 KBOs 6.5 NoemiPinilla-Alonso TennesseeRota+onallyresolvedstudyofthesurfaceofPlutoduringNASANewHorizonsflyby…

11112 Satellites 5.1 RichardCartwright TennesseeNorthPolarSurfacesoftheUranianMoons:CoatedwithCO2Frost?

11104 Comets 1.6 Ma]hewKnight LowellObs.P/1999R1:Sunskir+ngcometorasteroid?

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Spitzer as Solar System Investigator

•  Passive cooled operations at 3.6 and 4.5 µm using InfraRed Array Camera (IRAC) –  5 arcmin FOVs –  ~1.6 arcsec resolution –  1σ sensitivities in 100s are 21.2, 20.4 at

3.6 and 4.5 µm –  Saturate at 2 mag

•  Solar system science built into observatory –  Track at 1 arcsec / second –  Moving target support in observing mode

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Spitzer Orbit

6

IOC/SV Mission Lifetime Req't Thru Cryo Depletion Warm Mission

!

0.50 AU!

circle of radius 1 AU from Sun

Earth 1.50 AU!

Cryogen Depleted

Nov 2016 Oct 2018

Distance from Earth and geometry modify spacecraft heating, battery charging and downlink rates

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Spitzer Capabilities

•  Unique vantage point with respect to Earth (currently 1.4 AU away) –  Different path length through Zodiacal dust

cloud (could possible use shutter for Zody)

–  Different viewing angle for NEAs

•  ~7000 hours/year available for science observations

•  Can observe continuously for ~72 hours

•  Can observe targets quasi-continuously for 38 or more days (Need 2-4 hours gaps for downlinks every 24-72 hours)

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Spitzer Target Visibilities

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Long-term Photometric Stability

Absolute photometry stable to <0.5% over timescale of years Krick et al. (2015)

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Short-term Photometric Stability

Spitzer transits of GJ1214b 13

0.9860

0.9884

0.9908

0.9932

0.9956

0.9980

1.0004

Norm

alized

Flu

x

−0.04 −0.02 0.00 0.02 0.04Phase

−0.00020.00000.0002

Resid

uals

Fig. 5.— Phased & binned transit of GJ1214b at 4.5µm from our 13 Spitzer transits, plus the transit observed by Desert et al. (2011).

Phase

Rel

. Flu

x

12 Fraine et al.

10−4

10−3

RM

SS

catter

Theoretical√N−1

RMS Scatter

100 101 102 103

Time per Bin (s)

0.00000843

0.00003160

0.00005477

Diff

ere

nce

Fig. 4.— Standard deviation of the residuals (data minus the ‘simultaneous’ fit, in units of the stellar flux) for all 14 transits at 4.5µm,versus bin size. The red lines in the lower panel show a ±1σ envelope.

RM

S

Bin size in seconds

Fraine et al. (2013) measured transit depth of GJ1214b to precision of 40 ppm (radius to ~28 km) 14 consecutive transits coadded to produce final light curve Relative photometry < 100 ppm which is repeatable

10-3

10-4

1.0004

0.9860

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2011 MD – A Challenging Target

•  Spitzer tracked potential AARM target 2011 MD for 19.9 hours, covering a distance of 17.5 arcmin on the sky.

•  Shifting and adding data led to a 2.2 sigma detection (0.60+/- 0.27uJy) of asteroid at position consistent with prediction

•  Inferred diameter is 6m [4-10 is range]; density 1.1 g/cm+3

•  Suggest2011MDisarubble-pileasteroid

•  Asteroidwas~0.14aufromEarthatthe3me

•  ExploitedSpitzer’sEarth-trailingsolarorbit

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Asteroid (2867) Steins Example

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Create Observation

SBAG

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Visualize Observation

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Observation Planning Overview

•  Handled by SPOT user tool •  Find targets by NAIF ID or send orbital parameters to SSC •  Design observation – Final observations are submitted with

proposal •  Visualize observation •  Add a Shadow observation to measure background •  Constrain observation for specified date if desired or link

order of observations to have multiple epochs

•  Moving targets require special handling as they are observations that need to be fixed in time when scheduled

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Getting Data -- Spitzer Heritage Archive

Search for moving targets in the archive

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Precovery Tool

Search for moving targets in the archive

Find moving targets serendipitously observed by Spitzer

See Luisa’s talk about IRSA Services @ 1:30pm

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Final Thoughts

•  Plan to operate Spitzer through 2018 •  14000 hours available in 2017-2018

– Proposal deadline will be this summer •  Spitzer has unique capabilities for planetary

science and 3.6 and 4.5 µm data are unmatched until JWST

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Any Questions?

•  Contact the Helpdesk at the Spitzer Science Center –  help@spitzer.caltech.edu

•  Visit the Spitzer Science Center web pages –  http://ssc.spitzer.caltech.edu –  http://irsa.ipac.caltech.edu/data/SPITZER/docs/

spitzermission/observingprograms/solarsystemprograms/ –  http://irsa.ipac.caltech.edu/data/SPITZER/docs/files/

spitzer/SSO_Observing_With_Spitzer.pdf

•  Spitzer/IRSA demos on YouTube