0 Assigned ID: 6474 ----- Attempting Submission 1 (Thu Apr 10 15:11:28 GMT 2025) ----- First version of Phase 2 for program 18006. We are happy to edit anything (including scheduling) as needed. 645042656 ----- Attempting Submission 1 (Thu Jul 31 16:27:19 GMT 2025) ----- Geophysical Characterization of the Distant Ocean World Makemake Recent JWST observations have revealed that the trans-Neptunian object (TNO) Makemake has a prominant IR excess indicating the existence of Enceladus-style hotspots on its surface. This makes Makemake possibly one of the Solar System's most distant ocean worlds. Unfortunately, little is known about many of the basic properties of Makemake, making high-fidelity geophysical investigations almost impossible. To solve this, we propose an investigation to measure the mass, density, and pole-axis orientation of Makemake via astrometric tracking of its small satellite, nicknamed MK2. Measuring mass and density will help to constrain the ongoing radiogenic heating of Makemake and provide firm footing for models of Makemake's interior structure. Determining Makemake's pole-axis orientation will provide critical context for interpreting the JWST thermal measurements and could help to constrain the geographical extent of any hotspots. Leveraging over a dozen orbits from past HST programs, we require just 4 well-timed HST orbits to complete our investigation, which will revolutionize our knowledge of Makemake and enable high-fidelity geophysical modeling of this distant ocean world. Our observations call for 4 single-orbit visits to image the Makemake system using the WFC3/UVIS instrument. During each visit, images will be acquired using the UVIS2-C512C-SUB aperture, paired with the F350LP filter to optimize astrometric precision. Exposure times are chosen to optimize SNR and schedulability, with 10+ dithered images taken during each visit. This allows us to remain robust to unlucky cosmic ray hits. Scheduling of observations is important to the goals of our program. The timing windows input into the Phase II are somewhat flexible, and can be changed if needed. If more observing windows are needed, we can provide them, although these are our "optimal" windows. We would prefer if each visit is at least 18 days apart, although this is not strictly necessary. Since poorly oriented diffraction spikes can degrade the astrometric quality of our observations, we request observations avoid orients where the diffraction spikes are aligned with the satellite's orbit. Inputting these a priori is difficult/time-consuming since the position of the satellite and orient ranges change in time. Once preliminary scheduling windows based on "betweens" are identified, we can further input the orients which are allowed. We will also check for bright nearby stars that could degrade image quality. Dr. Benjamin Proudfoot is a postdoctoral scholar at the University of Central Florida. He is an expert in non-Keplerian orbit fitting of TNO moons and the lead developer of the MultiMoon code, which will be used to do all orbit fitting in this investigation. He has led several past studies focusing on understanding the orbits of TNO moons, including other dwarf planet moons. Dr. Bryan Holler is a MIRI instrument scientist at STScI and his research focus is on near-infrared spectroscopy of trans-Neptunian objects (TNOs). He has previous experience working with JWST and HST programs as well as PSF fitting of TNO binaries. Dr. Darin Ragozzine is an expert in TNO satellite orbit fitting, with extensive experience in detecting non-Keplerian effects. He has been PI of multiple HST programs focusing on understanding the formation, evolution, and physical characteristics of TNOs. He was the PI/Co-I of 5+ programs to study the orbits of Haumea's moons. Dr. Will Grundy is a major expert in HST data reduction and analysis for TNBs. He has led several programs focusing on characterization of individual TNB systems. He maintains an extensive online catalog of TNBs. He was also a Co-I on previous proposals to study MK2's orbit. Solar System Astronomy 6 false false false false false false SUPPORTED SOLAR SYSTEM DWARF-PLANET Makemake STD=MAKEMAKE EARTH WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false Timing link suitability includes constraints ([02 After 01 by 18.0 to 365.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18006 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:44:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 54928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18006 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18006 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2574 :al-overhead-at-end 0 :internal-dur-at-end 97 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([02 After 01 by 18.0 to 365.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18006 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:44:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 54928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18006 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18006 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2574 :al-overhead-at-end 0 :internal-dur-at-end 97 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([04 After 03 by 9.0 to 365.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18006 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:45:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 54928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18006 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18006 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2574 :al-overhead-at-end 0 :internal-dur-at-end 97 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0 Timing link suitability includes constraints ([04 After 03 by 9.0 to 365.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18006 :visit-id "04" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:45:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 54928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18006 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18006 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2574 :al-overhead-at-end 0 :internal-dur-at-end 97 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0