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Siding Spring at Mars: BOPPS Observations Andrew Cheng (JHU/APL)

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Presentation on theme: "Siding Spring at Mars: BOPPS Observations Andrew Cheng (JHU/APL)"— Presentation transcript:

1 Siding Spring at Mars: BOPPS Observations Andrew Cheng (JHU/APL)

2  BOPPS science objectives  BIRC calibration results  UVVis update  Science operations 8/11/142 Overview CIOC

3  BOPPS 2014 Mission Targets  Oort Cloud comets C/2012 K1 (PanSTARRS) and C/2013 A1 (Siding Spring) Measure water, CO 2, and dust activities Coordinated Earth-based and Mars-based observing of Siding Spring Coordinated Earth-based observing of PanSTARRS  Dwarf Planets Ceres and Vesta Hydrated surfaces on Ceres and Vesta Variable water vapor emission from Ceres  Uranus Resolved disk imaging Demonstrate UVVis fine pointing system 8/11/ Flight Science CIOC

4 Comet Siding Spring  Siding Spring will make an extremely close approach to Mars on October 19, 2014  Event to be observed by Mars spacecraft, as well as other missions  High resolution images and spectra of an Oort Cloud comet nucleus (HiRise m per pixel)  BOPPS flight from Fort Sumner can measure CO 2 and H 2 O emissions from this comet a few weeks before Mars encounter  A more difficult observation than PanSTARRS 4 CIOC 8/11/14 Unique characterization of CO 2 /H 2 O ratio in conjunction with an international campaign of observations

5  Ceres, Dawn mission target in 2015  A dwarf planet, the largest asteroid, with ~1/3 the entire mass of the main belt  A hydrated asteroid with 3µm spectral features  Water vapor emission  Vesta, a basaltic asteroid, unexpectedly reported by Dawn to have hydrated minerals 8/11/145 Ceres and Vesta CIOC DeSanctis et al. ApJL 758:L36 Ceres spectra (black and red) compared to CM meteorite (green) and model spectra (other lines) Rivkin et al. Icarus 185:563, 2006 Demonstration of Discovery-class science and synergistic role with other missions

6  BIRC is a multispectral IR imager with cryogenic HgCdTe detector  Cooled filter wheel and relay optics  Filters at  2.47  m  2.70  m  2.85  m  3.05  m  3.20  m  4.00  m  4.27  m  4.60  m  R band (600 – 800 nm)  FOV 3 arcmin  1.16 arcsec/pixel plate scale with 18  m pixel pitch  12 bit images 8/11/146 BIRC Summary CIOC water and continuum CO 2 and continuum Cold/Mini-Bench Primary hex bench (composite) Filter wheel & Enclosure Camera Asphere Fold Mirrors Window “2”

7 8/11/147 BIRC Filter Numbers CIOC Filter NumberCenter Wavelength 1R-band 24.6 µ 34.0 µ µ 52.7 µ µ 73.2 µ µ µ #2 #5 #8 #6 #9 #7#4#3 Continuum subtraction and ratio of CO 2 to H 2 O emissions, using eight NIR spectral filters; R-band filter not shown

8  BIRC photon transfer test from August, 2013 in altitude thermal chamber  Read noise is 1.67 ± DN  Measured non-linear gain characteristic  Saturation is at 1800 DN or ~100,000 electrons  SNR (read and shot noise) exceeds 100 above 300 DN; exceeds 200 above 900 DN 8/11/148 BIRC Noise, Gain, Linearity CIOC Above right: red symbols, gain versus DN Left: Cumulative electrons detected versus DN Right: SNR from read noise and shot noise, versus DN

9 8/11/149 CIOC 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  m pixel pitch  Guide channel  Fast framing CMOS imager  600 – 850 nm broad band  sCMOS detector with image format 2560x2160  Plate scale 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

10 8/11/1410 UVVis with Fine Steering Mirror GoalDesiredActualEvidence Coarse gondola/OTA pointing Pointing envelope (3- sigma) of ± 10 ” over 1- min Typical behavior: 3- sigma < 3 ” Observed w. Star Cameras Error signal quality (centroids) 0.1 pixel resolution at 20 Hz Centroids determined at 50 & 100 Hz (for 60” and 40 ” FOVs) Hang tests using the FSM reduced FWHM from 3 ” to 1.5 “, which is the theoretical expectation Motion compensation (Fine Steering Mirror) Control of FSM at 0.1 pixel level at 4-5 Hz FSM driven at 500 Hz to correct for 100 Hz motion During hang test at launch site, a single 5 ms exposure with FSM on During hang test at launch site, average of 50 frames with FSM on: FHWM reduced to 1.5” CIOC

11 UVVis Commis -sioning BIRC UVVis 8/11/1411 BOPPS Mission Timeline Notional Mission on September 24 CIOC 90,000 ft 120,000 ft ASCENT L1 missionBaseline mission PanSTARRS Siding Ceres Vesta Jupiter Mizar Castor PanSTARRS Uranus Jupiter Mizar Castor Spring stars PanSTARRS TARGETS Vesta Mizar Siding Spring Vesta Ceres Mizar Uranus

12 8/11/1412 Comet Siding Spring CIOC  Siding Spring will make an extremely close approach to Mars on October 19, 2014  Event to be observed by Mars spacecraft, as well as other missions  High resolution images and spectra of an Oort Cloud comet nucleus (HiRise m per pixel)  BOPPS flight from Fort Sumner can measure CO 2 and H 2 O emissions from this comet a few weeks before Mars encounter  A more difficult observation than PanSTARRS Unique characterization of CO 2 /H 2 O ratio in conjunction with an international campaign of observations

13 8/11/1413 Siding Spring Brightness CIOC Discovered 3 Jan 2013 by R. McNaught An Oort Cloud comet which encounters Mars near perihelion JPL predicted magnitudes are fainter than shown by Yoshida: 9.65 on 9/15/ on 10/1/14 First day in September that comet gets at least 8 degrees above horizon for an hour is 9/24/14 Seichi Yoshida Perihelion JPL

14 8/11/1414 PanSTARRS Brightness CIOC Seichi Yoshida Perihelion JPL  Discovered May 19, 2012  A bright Oort Cloud comet  Perihelion: Aug 27, 2014  JPL predicted magnitudes are fainter than those predicted by Yoshida:  8.4 on 9/15/14  8.2 on 10/1/14 High SNR determination of CO 2 /H 2 O ratio


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