BOPPS Observations of Oort Cloud Comets and Ceres

Andy Cheng (APL) Karl Hibbitts (APL) Eliot Young (SwRI)

Pietro Bernasconi (APL) Tibor Kremic (NASA GRC)

BOPPS Overview

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Balloon Observation Platform for Planetary Science: • Stratospheric balloon-borne observations above

99.6% of atmosphere ‒ Superior seeing vs. ground-based observations ‒ View wavelengths at which the atmosphere is

opaque • BOPPS flight Sept. 25-26, 2014 from Ft. Sumner, NM

‒ Observed H2O and CO2 wavelengths from an Oort Cloud comet

‒ Demonstrated sub-arcsecond pointing stability

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BOPPS Objectives

Develop and demonstrate gondola and payload systems for a balloon-borne platform ‒ IR imaging of Oort Cloud Comet ‒ NUV/Vis imaging and demonstration of Fine Steering

Mirror for obtaining sub-arcsec pointing stability Achieve high-value planetary science objectives ‒ Measure CO2 and H2O in an Oort Cloud comet and

determine their ratio ‒ Observe other high-value targets as available

Program management NASA GRC ‒ Project management, gondola, and integration APL ‒ BIRC payload APL; UVVis payload SwRI

NASA GRC 12/5/14

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BOPPS Gondola Description

Estimated MEV Mass

Dry 4134 lbs.

LN2 178 lbs.

Ballast 750 lbs.

Total Wet 5062 lbs.

Dry mass includes 345 lbs. of CSBF equipment (CIP/MIP, ballast hopper, science stack, live video transmitter with radiator plate, antennas & harness)

Maximum Suspended mass allowable: 5200 lbs.

STO 0.8 m Telescope

UVVis

BIRC

LN2 Dewars (x2)

CIP/MIP Package

Telescope Baffle Extension

Azimuth Reaction Wheel Suspension Point

Star Cameras (x2)

Avionics and Power bay

Roll Reaction Wheel

20’

Antenna boom

Science Instruments

Suite

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BIRC Instrument Overview

BIRC is a multispectral IR imager with cryogenic HgCdTe detector

Cooled filter wheel and relay optics Filters at

2.47 µm 2.70 µm 2.85 µm 3.05 µm 3.20 µm 4.00 µm 4.27 µm 4.60 µm R band (600 – 800 nm)

FOV 3 arcmin 1.16 arcsec/pixel plate scale with 18 µm

pixel pitch 12 bit images

water and continuum

CO2 and continuum

Filter wheel & Enclosure

IR Camera

Asphere

Fold Mirrors

Window “2”

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UVVis Instrument Overview

Science channel CCD camera with filter wheel 4 bandpass filters ( 300 – 450 nm ) Broad band ( < 300 – 600 nm ) Frame format 1024x1024 with optional

EMCCD Plate scale 0.19 arcsec/pixel with 13 µm pixel

pitch Guide channel

Fast framing CMOS imager 600 – 850 nm broad band sCMOS detector with image format

2560x2160 Plate scale 0.096 arcsec/pixel with 6.5 µm

pixel pitch Controls a fine steering mirror for fine image

stabilization to ~ 0.1 arcsec Inset fold mirror

Movable into the telescope light beam Divert light from telescope into UVVis optic Open lets light reach BIRC instrument

Guide camera

Science camera

Fold mirror Fast steering mirror

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BOPPS Pointing Stability

Coarse Pointing significantly exceeded mission requirement of 1 arcsec

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Achieved 0.5 arcsec RMS stability

Two 20-sec observing sequences on Polaris quantified ability to (a) obtain a pointing error signal at 50 and 246 Hz and (b) compensate for pointing errors below 5 Hz.

Performed rapid focus run using star image metrics (not images).

Pointing stabilization tests with and without BIRC cryocooler operating.

Performed fine image motion corrections RMS pointing errors were reduced to 280 & 165 mas

(AZ and EL) with the cryocooler ON RMS was 33.3 & 58.1 mas with the cryocooler OFF.

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UVVis Stabilized Pointing

NASA GRC 12/5/14

Young EF et al.

Launch delayed 1.5hrs by ground-level winds to 8:30 am Shortened commissioning Insufficient time to acquire morning targets:

PanSTARRS and Vesta. UVVis demonstrated operation of FSM BIRC observed Oort Cloud comets Siding

Spring (H2O detections) and Jacques (H2O and CO2 detections); also Ceres

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BOPPS as flown Sept. 25, 2014

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Target rH [AU] δ [AU] Phase [deg.]

Calibration star (type) mag

Detections [band center in µm]

Siding Spring C/2013 A1 1.46 1.12 43 HD163761

(A0V) V=6.69 R, 2.7, 2.47, 4.0

Jacques C/2014 E2 1.72 1.15 34 HD196724

(A0V) V=4.82 R, 2.7, 2.47, 3.05, 3.2, 4.0, 4.27

1 Ceres 2.75 3.37 15 HD133772 (A0V) V=7.47 R, 2.7, 2.47, 3.05, 3.2

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BIRC Observations

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PanSTARRS was a daytime target (not observed); Siding Spring and Ceres were twilight targets; Jacques was a night time target.

The 2.7µm water and 4.27µm CO2 emission wavelengths were observed from Jacques.

Coordinated IRTF observations: Poster P43A-3973 Lisse CM et al.

BOPPS detection of Comet C/2014 E2 (Jacques)

H2O emission at 2.7µm wavelength Four images of 15 sec exposure each

CO2 emission at 4.3µm wavelength Eight images of 59 sec exposure each Comet moves toward left in oval

CO2 Observations (unique)

H2O Observations

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Level 1 science observations

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BOPPS Observations of Comet C/2013 A1 Siding Spring

• Siding Spring observed in R band (641 nm) R=10.6

• Siding Spring water emission measured at 2.7 µ with Q[H2O]=4e27 /sec

00:20:15 UT 00:35:30 UT 00:50:39 UT

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Direct measurement of water production from Siding Spring

Ceres, the Dawn mission target in 2015 A dwarf planet,

with ~1/3 the entire mass of the main belt

A hydrated asteroid with 3µm spectral features

Water vapor emission

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Ceres

NASA GRC

Ceres spectra (black and red) compared to CM meteorite (green) and model spectra (other colored lines) Rivkin et al. Icarus 185:563, 2006; Ceres spectrum (grey line) Vernazza et al. A&A 436:1113, 2005 (also IRTF)

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BOPPS filters

Hibbitts CA et al.

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Preliminary Photometry

NASA GRC

S. Yoshida

BOPPS

Not corrected for target thermal emission

BOPPS Left, Ceres

Center, Jacques

Right, Siding Spring

2014 BOPPS Successful Flight

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Targets seen against bright background from sky and thermal self-emission Equal observing times on each target and its

calibration star All observations were scripted (e.g., ~50,000

images of HD196724) Take many short exposures (short to avoid

saturation) and co-add, subtract background Separate calibration star, near target in sky,

observed for each target Flux calibration of each filter from calibration star Same stars observed in coordinated IRTF

observation

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Observing Strategy

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Images acquired in pairs (bias and exposure) for bias subtraction

Images (target and calibration star) acquired in two sets (A, B) with pointing nod between them

Bad pixel removal by 5x5 median filtering (with peak preservation algorithm)

Co-adding frames, image shift based on high rate IMU data

Flat field from set A for set B and visa versa Aperture photometry for sky background

subtraction 18

BIRC Image Processing

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