Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 25 Report Date: 18-Jul-95:16:17 Version: ********** Check-in Date: ********** 1.Proposal Title: THE EXCITATION OF THE ATMOSPHERES OF PLANETARY SATELLITES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GO Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Joe Astronomer STSCI USA (301) 338-4700 ------------------------------------------------------------------------------------ 7. Abstract We will observe Io at near and far UV wavelengths in a set of observations designed to study the excitation of the satellite atmospheres. The distinguishing element of this program is the design of the observations to separate the following processes: resonant scattering of solar emission, charged particle excitation by magnetospheric plasma, and (in the case of Io) the decay of the atmosphere in the absence of solar- driven sublimation from the surface. Io will be observed with the FOS/HST combination in the far-UV over a period of time centered on the passage of Io into eclipse to separate the solar emissions (while sunlit) from particle excited emissions (while in shadow) and the near UV SO2 aurora will be observed while Io is in shadow. The far UV lines of atomic sulfur and oxygen emanate from an extended atmosphere, and are produced by a combination of resonant scattering of solar emission and plasma impact relatively high in the atmosphere. The near-UV bands of SO reflect particle impact on SO2, the parent molecule believed to be driven by sublimation vapor pressure from the surface, and may be excited relatively closer to Io's surface (due to the ------------------------------------------------------------------------------------ 8. Scientific Key Words: PLANETARY SATELLITE, PLASMA TORUS, AURORA ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 25 PI: Dr. Joe Astronomer Proposal Title: THE EXCITATION OF THE ATMOSPHERES OF PLANETARY SATELLITES ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Joe Astronomer SPACE TELESCOPE SCIENCE USA INSTITUTE ------------------------------------------------------------------------------------ 3. Description of proposed observations. The observations will consist of: i) a series of FOS/blue 4.3 arc sec aperture 15 min. RAPID spectra of Io beginning 10-15 minutes before eclipse disappearance of Io for a period of 40 min. (or as long as possible in one dark orbit), and ii) a series of FOS G270H 4.3 arc sec aperture 15 min. RAPID spectra beginning near the time of eclipse disappearance for one dark orbit. The total is 2 dark orbits with the priority listed above. Acquisition of Io requires short spectra at different y-deflections to center in y (IO_TA). Using the 4.3 arc sec aperture to optimize the sensitivity to diffuse emission, we request coarse track to avoid any loss of lock. In both cases, Io is to be observed when it is in the active sector of Jupiter's magnetic field and also in the Io plasma torus, i.e. when the sub-Io CML of Jupiter is 240-310 degrees. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Justification for use of HST goes here. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. As discussed above, the efficiency of the HST/FOS to a 1 arc sec object with G130H is roughly 0.5 cts/sec-kR for diffuse emission; HST/FOS with G270H and 1 arc sec aperture will yield roughly 2 cts/sec-kR. The S/N estimates given above are based on 30-40 min. integrations in a single dark orbit per observation. The time for acquisition of two guide stars in coarse track (no fine lock) is estimated to be 5 min. FOS acquisitions cannot be used while tracking Io with track 51, so a real-time uplink is needed to center Io in the Y-direction (1.3 arc sec diode length). We will accept the blind blind ponting in X. We define a target IO-TA for 5 spectra of Io in sunlight at different y-deflections: the real -time uplink will be used to select the optimum y-deflection for the science data. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. The observations of Io must begin 10-15 minutes before Io eclipse disappearance. To be able to follow Io in the shadow of Jupiter, the sun-Earth-Jupiter angle must be 90 +/- 25 degrees. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. A description of your data reduction plans go here. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Any additional comments go here. ------------------------------------------------------------------------------------ 9. Description of previous HST work. A description of any previous HST data goes here. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Resources provided by your home institution goes here. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: JOE ASTRONOMER Category: PI Institution: STSCI Address: 3700 SAN MARTIN DRIVE City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: (301) 338-4700 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 25 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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 | | OLG OF JUPITER BETWEEN 54 104, | ECL U OF IO BY JUPITER, | CML OF JUPITER FROM IO BETWEEN 240 310, | SEP OF EUROPA IO FROM EARTH GT 10", | SEP OF GANYMEDE IO FROM EARTH GT 10", | SEP OF CALLISTO IO FROM EARTH GT 10" | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |SURF(V) = 5.8 +/- 0.5 | OBSERVE IO GOING INTO ECLIPSE BEHIND 2 |SIZE = 1.0 +/- .2 | JUPITER; BEGIN G130H SERIES 10-20 3 |SURF-CONT(2700) = 2 +/- 1 E-13 | MIN AND G270H SERIES 0-9 MINUTES | | BEFORE IO ECLIPSE DISAPPEARANCE AND | | SCHEDULE WHEN EARTH-SUN-JUPITER | | ANGLE IS 54-104 DEGREES AND CML OF | | SUB-IO POINT ON JUPITER IS 240-310 | | DEG. PLEASE NOTE THAT THE WINDOWS | | CAN BE EXPANDED IF NEEDED TO | | SCHEDULE. | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: IO-TA ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: SATELLITE IO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = JUPITER | STD = IO | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |SURF(V) = 5.8 +/- 0.5 | IO-TA IS IO IN SUNLIGHT FOR TARGET 2 |SIZE = 1.0 +/- .2 | ACQUISITION WITH FOS. THIS WILL BE A 3 |SURF-CONT(2700) = 2 +/- 1 E-13 | SET OF 5 SPECTRA AT DIFFERENT Y- 4 |SURF-CONT(1600) = 2 +/- 1 E-14 | DEFLECTIONS TO DETERMINE WHERE IO IS | | CENTERED ON THE 1.3 ARC SEC LONG FOS | | DIODES. | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 25 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IO-TA FOS/BL IMAGE 4.3 G270H Y-SIZE=5 1 300 S 2 1 RT ANALYSIS FOR 2- Y-SPACE=128 3.1 COMB=YES CYCLE 1 /1-6.1 SUB-STEP=4 Comments: FOS SPECTRA OF IO FOR TARGET ACQ. BEFORE EA. OF 2 SPECTROSCOPY SESSIONS: W/ G130H AND G270H. REQUIRES RT UPLINK WILL UPLINK CORRECT POINTING DURING EARTH OCC BASED ON 5 SPECTRA IN OSS IO WILL BE RE- ACQ'D.TAKE 2-3 POST OCC. ------------------------------------------------------------------------------------------------------------------------------------ 2 IO-TA FOS/BL IMAGE 4.3 G270H STEP-TIME=1.0 1 4.0S 2 2 SEQ 2-3.1 NO GAP SUB-STEP=1 Y-SIZE=4 Y-SPACE=64 COMB=NO Comments: QUICK MAP OF 4.3 APERTURE,AFTER UPLINK CORRECTING POINTING, TO DETERMINE TRUE LOCATION OF IO IN APERTURE. ------------------------------------------------------------------------------------------------------------------------------------ 3 IO FOS/BL RAPID 4.3 G130H 1368. STEP-PATT=DEF 1 1590S 1 1 READ-TIME=40 Comments: BEGIN EXPOSURES AFTER ACQ MAP AND 5-10 MINUTES BEFORE IO ECLIPSE DISAPPEARANCE. ------------------------------------------------------------------------------------------------------------------------------------ 3.1 IO FOS/BL RAPID 4.3 G130H 1368. STEP-PATT=DEF 1 170S 1 1 READ-TIME=40 ------------------------------------------------------------------------------------------------------------------------------------ 4 IO-TA FOS/BL IMAGE 4.3 G270H Y-SIZE=5 1 300S 2 1 RT ANALYSIS FOR 5- Y-SPACE=128 6.1 COMB=YES SUB-STEP=4 Comments: 5-STEP IMAGE FOR RT POINTING CORRECTION BEFORE 5,6. MUST OCCUR WITH IO IN SUNLIGHT. ------------------------------------------------------------------------------------------------------------------------------------ 5 IO-TA FOS/BL IMAGE 4.3 G270H STEP-TIME=1.0 1 4.0S 2 3 SEQ 5-6.1 NO GAP SUB-STEP=1 Y-SIZE=4 Y-SPACE=64 COMB=NO Comments: QUICK MAP OF 4.3 APER FOR GROUND TRUTH POINTING INFO. MUST OCCUR BEFORE LINE 6. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 25 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 IO FOS/BL RAPID 4.3 G270H STEP-PATT=DEF 1 1590S 1 1 READ-TIME=40. Comments: 40 S. SPECTRA OF IO: BEGIN 0-5 MIN. BEFORE ECLIPSE OF IO BY JUPITER. ------------------------------------------------------------------------------------------------------------------------------------ 6.1 IO FOS/BL RAPID 4.3 G270H STEP-PATT=DEF 1 170S 1 1 READ-TIME=40. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 25 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters Y-SIZE Y-SPACE COMB SUB-STEP STEP-TIME STEP-PATT READ-TIME ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements RT ANALYSIS FOR 2-3.1; CYCLE 1 /1-6.1; SEQ 2-3.1 NO GAP; RT ANALYSIS FOR 5-6.1 SEQ 5-6.1 NO GAP; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G270H G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names IO IO-TA ------------------------------------------------------------------------------------------------------------------------------------