13805( 6) - 22-Dec-2014 20:36:04 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13805 Version: 6 Check-in Time: 22-Dec-2014 20:36:04 STScI Edit Number: 4 Title Io's Atmosphere Silhouetted in Transit by Jupiter Lyman-alpha ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kurt D. Retherford Southwest Research Institute Y CoI: Dr. Lorenz Roth Royal Institute of Technology N CoI: Dr. Lori M. Feaga University of Maryland N CoI: Dr. Cesare Grava Southwest Research Institute N CoI: Dr. Kandis Lea Jessup Southwest Research Institute N CoI: Dr. Constantine Tsang Southwest Research Institute N ------------------------------------------------------------------------------------ Abstract Io's active volcanos both directly establish local gas plumes and indirectly establish a more global sublimation atmosphere, through plume deposited sulfur dioxide frost patches. Despite decades of study and recent observational advances the very basic question about the relative role of each of these sources is unresolved. The correlation between volcanic activity variability and Io's dramatic influence on numerous time-variable phenomenon in the Jupiter system cannot be causally linked until this answer is in hand. Our experienced team has developed a novel approach to use STIS in a new way to obtain global radial profiles of SO2 scale height distributions above both plume and sublimation dominated regions. We exploit the bright Lyman-alpha dayglow of Jupiter as a background illumination source together with the strongly absorptive nature of SO2 at 121.6 nm to image Io's atmosphere in silhouette with unprecedented detail during transit events. Our program provides the following key information for SO2: 1) First high-altitude (>400 km) radial measurements of tangential column densities and scale heights; 2) First clear measurement of sublimation densities at polar locations; 3) Volcanic densities for large and mid-sized plumes (possibly new ones); 4) Globally distributed limb profiles allowing strong distinctions between plume and sublimation dominated locations; 5) Repeated imaging on a few day and a few week timescales for improved plume variability constraints; and 6) Lyman-alpha reflectance imaging at Io central lon. ~180 deg, filling a gap in previous coverage. These new information are critical to breaking through an impasse in our understanding of Io's atmosphere. ------------------------------------------------------------------------------------ Observations Description ------------------------ Io transits Jupiter during each of 4 requested visits with one HST orbit each. The STIS G140M mode is used with the 52"x2" slit, which completely images the 1.16" disk of Io and its surrounding gas. Central wavelength 1222A selects the Lyman-alpha feature at 121.6 nm within its 119.4-124.9 nm range. The medium resolution mode dispersion is needed for spectral purity compared with STIS G140L, and diminishes potential confusion from nearby Jupiter continuum, Io aurora, and plasma torus features. Four visits with 1 orbit each are needed to search for plume density 13805( 6) - 22-Dec-2014 20:36:04 - [ 2] variability. To achieve the goal of constraining the timescales for variability in plume gas densities, two visits should be separated by a few days near Jupiter opposition and one additional visit each should be separated by ~3 weeks before and after opposition, respectively. The proximity to Jupiter opposition in Feb. 2015 both maximizes the spatial resolution and reduces the contribution of foreground geocoronal Lyman-alpha background signals, as the geometry is aligned with Earth shadow. Observations within a few weeks of opposition (February 5, 2015) hence maximize both the size of Io and the amount of time in Earth's shadow, reducing the background from terrestrial airglow emission from ~10-15 kR to instead ~2.5-4 kR. An essential requirement is to capture Io while in transit near Jupiter's central meridian. ------------------------------------------------------------------------------------ 13805( 6) - 22-Dec-2014 20:36:04 - [ 3] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 TARGET NAME: IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS TRANSIT OF IO ACROSS JUPITER FROM EARTH, SEP OF IO CALLISTO FROM EARTH GT 2", SEP OF IO EUROPA FROM EARTH GT 2", SEP OF IO GANYMEDE FROM EARTH GT 2", SIZE IO GT 1.0 ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.2 +/- 0.1 Io is targeted while it transits the disc of Jupiter. An ideal program would further constrain one visit/orbit to occur when Io is located exactly in the center of the Ephemeris Center: EARTH plasma torus, i.e. with sub-Jupiter system III latitude of 0 deg (i.e., CML=110 deg or 290 deg) and the other three visits to occur when Io is located at the extrema of the torus (i.e., CML=20 deg or 200 deg). Torus proton charge exchange induced auroral Lyman-alpha is expected to contribute a signal of 200-500 R in the same above limb region (Trafton, AJ, 2000). One orbit at low latitudes when the charge exchange rates are highest would test this process. The scheduling odds are good that this distribution would occur by happenstance, and so specific observing windows are not included for this 'nice-to-have' constraint. However, no more than two of the four visits should occur with Io at low magnetic latitudes, so that our primary SO2 attenuation measurement are not compromised. ------------------------------------------------------------------------------------------------------------------------------------ 13805( 6) - 22-Dec-2014 20:36:04 - [ 4] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 TARGET NAME: EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=EUROPA ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS NOT TRANSIT OF EUROPA ACROSS JUPITER FROM EARTH, NOT ECL U OF EUROPA BY JUPITER, SEP OF EUROPA JUPITER FROM EARTH GT 2", SEP OF EUROPA CALLISTO FROM EARTH GT 2", SEP OF EUROPA GANYMEDE FROM EARTH GT 2" ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 5.3 +/- 0.1 For target acquisition when Io is in Jupiter transit. Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 3 TARGET NAME: GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=GANYMEDE ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF GANYMEDE JUPITER FROM EARTH GT 2", SEP OF GANYMEDE CALLISTO FROM EARTH GT 2", SEP OF GANYMEDE EUROPA FROM EARTH GT 2", NOT TRANSIT OF GANYMEDE ACROSS JUPITER FROM EARTH, NOT ECL U OF GANYMEDE BY JUPITER ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 4.6 +/- 0.1 For target acquisition when Io is in Jupiter transit. Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 13805( 6) - 22-Dec-2014 20:36:04 - [ 5] TARGET LIST Solar System Targets ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 4 TARGET NAME: CALLISTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE CALLISTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 TARGET POSITION LEVEL 2 STD=JUPITER STD=CALLISTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 WINDOWS SEP OF CALLISTO JUPITER FROM EARTH GT 2", SEP OF CALLISTO EUROPA FROM EARTH GT 2", SEP OF CALLISTO GANYMEDE FROM EARTH GT 2", NOT TRANSIT OF CALLISTO ACROSS JUPITER FROM EARTH, NOT ECL U OF CALLISTO BY JUPITER ------------------------------------------------------------------------------------------------------------------------------------ DATA COMMENTS V = 4 +/- 0.1 For target acquisition when Io is in Jupiter transit. Ephemeris Center: EARTH ------------------------------------------------------------------------------------------------------------------------------------ 13805( 6) - 22-Dec-2014 20:36:04 - [ 6] Visit: 01 Visit Requirements: BETWEEN 01-JAN-2015:00:00:00 AND 12-MAR-2015:00:00:00 On Hold Comments: Additional Comments: Highest accuracy guide-star tracking is desired. Consider minimizing BUFFER time down from 600 sec to reduce time lost between exposures. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=19, 1 0.1 S (0.1 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Satellite can be changed to Ganymede or Callisto (Target GANYMEDE-ACQ / CALLISTO-ACQ) if more suitable for acquisition. The CHECKBOX parameter needs to be changed to 27 (GANYMEDE) or 25 (CALLISTO). ------------------------------------------------------------------------------------------------------------------------------------ 2 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 QASISTATES STIS CCD -MAMA G S) OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ 3 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 QASISTATES STIS CCD -MAMA G S) OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IO 2 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G IO 3 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G 13805( 6) - 22-Dec-2014 20:36:04 - [ 7] Visit: 02 Visit Requirements: BETWEEN 01-JAN-2015:00:00:00 AND 12-MAR-2015:00:00:00 On Hold Comments: Additional Comments: Highest accuracy guide-star tracking is desired. Consider minimizing BUFFER time down from 600 sec to reduce time lost between exposures. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=19, 1 0.1 S (0.1 GS ACQ SCENARIO BASE1B3 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Satellite can be changed to Ganymede or Callisto (Target GANYMEDE-ACQ / CALLISTO-ACQ) if more suitable for acquisition. The CHECKBOX parameter needs to be changed to 27 (GANYMEDE) or 25 (CALLISTO). ------------------------------------------------------------------------------------------------------------------------------------ 2 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 GS ACQ SCENARIO BASE1B3; -MAMA G S) QASISTATES STIS CCD OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ 3 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 QASISTATES STIS CCD -MAMA G S) OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IO 2 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G IO 3 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G 13805( 6) - 22-Dec-2014 20:36:04 - [ 8] Visit: 03 Visit Requirements: BETWEEN 01-JAN-2015:00:00:00 AND 12-MAR-2015:00:00:00 On Hold Comments: Additional Comments: Highest accuracy guide-star tracking is desired. Consider minimizing BUFFER time down from 600 sec to reduce time lost between exposures. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=19, 1 0.1 S (0.1 GS ACQ SCENARIO BASE1B3 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Satellite can be changed to Ganymede or Callisto (Target GANYMEDE-ACQ / CALLISTO-ACQ) if more suitable for acquisition. The CHECKBOX parameter needs to be changed to 27 (GANYMEDE) or 25 (CALLISTO). ------------------------------------------------------------------------------------------------------------------------------------ 2 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 GS ACQ SCENARIO BASE1B3; -MAMA G S) QASISTATES STIS CCD OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ 3 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 QASISTATES STIS CCD -MAMA G S) OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IO 2 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G IO 3 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G 13805( 6) - 22-Dec-2014 20:36:04 - [ 9] Visit: 04 Visit Requirements: BETWEEN 01-JAN-2015:00:00:00 AND 12-MAR-2015:00:00:00 On Hold Comments: Additional Comments: Highest accuracy guide-star tracking is desired. Consider minimizing BUFFER time down from 600 sec to reduce time lost between exposures. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EUROPA STIS/CCD ACQ F28X50LP MIRROR ACQTYPE=DIFFUSE, CHECKBOX=19, 1 0.1 S (0.1 GS ACQ SCENARIO BASE1B3 DIFFUSE-CENTER=GEOMETRIC-CENTE S) R Comments: Satellite can be changed to Ganymede or Callisto (Target GANYMEDE-ACQ / CALLISTO-ACQ) if more suitable for acquisition. The CHECKBOX parameter needs to be changed to 27 (GANYMEDE) or 25 (CALLISTO). ------------------------------------------------------------------------------------------------------------------------------------ 2 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 GS ACQ SCENARIO BASE1B3; -MAMA G S) QASISTATES STIS CCD OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ 3 IO STIS/FUV TIME-TA 52X2D1 G140M 1222 BUFFER-TIME=600 1 800 S (800 QASISTATES STIS CCD -MAMA G S) OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ EUROPA 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IO 2 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G IO 3 STIS/FUV TIME-TA 52X2D1 G140M 1222 none none none none 1 N/A -MAMA G 13805( 6) - 22-Dec-2014 20:36:04 - [ 10] Summary Form for Proposal 13805 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X2D1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE, BUFFER-TIME=600, CHECKBOX=19, DIFFUSE-CENTER=GEOMETRIC-CENTER ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-JAN-2015:00:00:00 AND 12-MAR-2015:00:00:00, GS ACQ SCENARIO BASE1B3, QASISTATES STIS CCD OPERATE OPERATE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names EUROPA, IO ------------------------------------------------------------------------------------------------------------------------------------