Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1292c Report Date: 09-May-96:16:26 Version: ********** Check-in Date: ********** 1.Proposal Title: SURFACE COMPOSITION OF PLUTO/CHARON ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID SOLAR SYSTEM GTO/OS Sub Category MINOR PLANETS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone John J. Caldwell YORK UNIVERSITY CANADA 416-736-2100 X PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract Pluto/Charon will be observed at both orbital elongations with the PC grism, to search CH4 absorptions features (undoubtedly from condensed CH4) on both. Previous spectroscopy from the ground has not been able to resolve the pair spatially, so that previous detections of CH4 features have been attributed to an average planet, not to the individual members of the pair. A special orientation will be needed, so that the two spectra do not overlap on the objective grating field of view, forcing the observations to be made near geocentric Solar opposition, where constraints on the spacecr aft roll angle due to power concerns will be minimized. Differences in the spectral characteristics of the two surfaces should be very easy to detect if they exist. ------------------------------------------------------------------------------------ 8. Scientific Key Words: PLUTO/CHARON, METHANE ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 1.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1292c PI: John J. Caldwell Proposal Title: SURFACE COMPOSITION OF PLUTO/CHARON ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ John J. Caldwell YORK UNIVERSITY CANADA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Two observations, separated by about 3 Earth days (i.e., by about 1/2 an orbital period for Pluto/Charon) will be made, preferably near Pluto opposition, so that role angle constraints are minimal. Roleangle, zero rotational phase will be specified when an approximate time for the observations is established. It is requested that the optimum position in the PC field be used for the grism observation. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. ST is required because the Pluto/Charon pair are so close together that their spectra cannot be individually recorded from the ground. Since Pluto is about two magnitudes brighter, its spectrum dominates the pair, and virtually nothing is known about the spectral nature of the fainter component, Charon. Ground-based observations can barely resolve the two in broad-band filter images using speckle techniques. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. There is no need for real time observations. Scheduling must put the observations at opposite orbital elongations, so that two hemispheres are observed independently. Also, it would seem to be most efficient to schedule the observations at Pluto opposition, so that the effects of role angle on power constraints can be minimized. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The two spectra (Pluto's and Charon's) will be compared to see if there is a difference attributable to CH(sub)4 absorption bands throughout the near infrared. There will be some blurring of the Pluto data because of its finite diameter. At this time, no grism observations of G stars havebeen requested, but that might change. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Other investigators will be observing Pluto with different science goals in mind. It would probably be convenient to schedule all such observations together. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). We have a dedicated SUN computer for data analysis. ------------------------------------------------------------------------------------ 13. Two 30 minute exposures, one at each orbital elogation, will be made of the Pluto/Charon pair with the PC grism (6000 - 10000 A) to search for CH4 absorption features on Charon as well as Pluto. There has not been any previous spatially resolved spectroscopy of this pair. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: JOHN J. CALDWELL Category: PI Institution: YORK UNIVERSITY Address: PHYSICS DEPT. City: NORTH YORK State: ON Zip Code: M3J 1P3 Country: CANADA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST b)Solar System Targets ID = 1292c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 1 | TARGET NAME: PLUTO-CHARON1 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = PLUTO | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF CHARON BETWEEN 80 100 | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V=17.3 | VISUAL MAGNITUDE IS FOR CHARON ONLY. | | (V=15.4 FOR PLUTO) TRK = 0.1 | ------------------------------------------------------------------------------------------------------------------------------------ TARGET NUMBER: 2 | TARGET NAME: PLUTO-CHARON2 ------------------------------------------------------------------------------------------------------------------------------------ TARGET DESCRIPTION: PLANET PLUTO ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 1 | TARGET POSITION LEVEL 2 | STD = PLUTO | | ------------------------------------------------------------------------------------------------------------------------------------ TARGET POSITION LEVEL 3 | WINDOWS | | OLG OF CHARON BETWEEN 260 280 | ------------------------------------------------------------------------------------------------------------------------------------ REF | DATA | COMMENTS | | 1 |V=17.3 | TRK = 0.1 | ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1292c [ 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 PLUTO- PC IMAGE ANY G800L 6000- 1 30M 100 1 2 ORIENT 131D +/- CHARON1 10000 60D / 1,2 CYCLE 2 / 1,2 GROUP 1,2 WITHIN 4D AT 8-MAY- Comments: OPTIMIZE POSITION OF IMAGE ON 1991:00:00:00 +/- ANY PC QUADRANT FOR BEST GRISM 15D SPECTRUM. SPECIFIED TIME IS PLUTO OPPOSITION, WHEN PLUTO IS 17 DEG FROM ANTI-SUN. ------------------------------------------------------------------------------------------------------------------------------------ 2 PLUTO- PC IMAGE ANY G800L 6000- 1 30M 100 1 2 CHARON2 10000 Comments: OPTIMIZE POSITION OF IMAGE ON ANY CCD QUADRANT FOR BEST GRISM SPECTRUM. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1292c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/OS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 1.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category SOLAR SYSTEM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category MINOR PLANETS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 131D +/- 60D / 1,2; CYCLE 2 / 1,2; GROUP 1,2 WITHIN 4D; AT 8-MAY-1991 00 00 00 +/- 15D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G800L ------------------------------------------------------------------------------------------------------------------------------------ Target Names PLUTO-CHARON1 PLUTO-CHARON2 ------------------------------------------------------------------------------------------------------------------------------------