<p>Atmospheric probes provide a critical method for understanding the Ice Giants, offering unique insight into atmospheric composition, structure, and dynamics. Such in situ measurements are vital to understanding the formation and evolution of these bodies and our solar system. To pursue these scientific opportunities space agencies are now turning their attention to the developmemnt of atmospheric probes to the Ice Giants and other bodies. The newly released Decadal Survey prioritized Uranus and Saturn probes as well as a Venus in situ explorer. Few such missions have flown and it is not likely that there will be other atmospheric entry probes until the DAVINCI+ Venus probe mission in the early 2030&#8217;s. Entry probe concepts such as these require a delicate balance between science objectives, orbital mechanics, atmospheres, and signal processing. The development of future entry probe missions will rely on tools which allow mission teams to concurrently filter and compare trajectories to optimize science return.</p> <p>To aid science planning for future entry probe missions we have developed a tool for Visualization of the Impact of PRobe Entry (VIPRE) conditions on science, mission and spacecraft design. VIPRE provides concurrent design capabilities for entry probe and lander missions by combining a precomputed database of optimized interplanetary trajectories with analytical models for entry point targeting, atmospheric descent and data-return rates. The user is able to explore the science trade-space using a GUI to constrain a variety of entry, trajectory, and data sufficiency parameters. Constraint-based interaction allows for direct, easy evaluation of scientific value and mission feasibility in real time. VIPRE is flexible to a variety of mission architectures allowing direct comparison of mission value between combinations of orbiters, entry vehicles and landers.</p> <p>Users primarily interact with VIPRE through a GUI. Figure 1 provides an illustration of some of the available mission design, science parameter and constraint intereractions within the VIPRE GUI. On its left edge, the GUI allows for the selection of a target body, Saturn in this case, and a range of filtering parameters. Based on these inputs, the GUI displays the top row of plots which indicate the filtered interplanetary trajectory parameters. Once a trajectory of interest is selected the &#8220;Overview&#8221; parameters are populated and the bottom row plots are generated to illustrate reachable probe entry locations, colored based on parameters of interest. Reachability, in this case, is defined by the selected filtering parameters as well as target specific constraints, i.e. avoiding Saturn&#8217;s rings. The GUI also allows for user definition of figures and filter parameters, shown in this example under the "Globe" and "Side by Side" tabs.</p> <p>This talk presents the motivation and models used for the development of VIPRE. Applications to Uranus and Saturn probe missions are discussed. Of particular interest is the accessibility of high and low latitudes for probe entry, how this is influenced by mission architecture (flyby versus orbiting probe release), and data constraints due to probe communications geometry.</p> <p>&#160;</p> <p><img src="" alt="" /></p> <p>Figure 1. Example of VIPRE trajectory selection for a Saturn probe mission</p> <p>&#160;</p> <p>[1] Probst, A. et al, VIPRE: A Tool Aiding the Design for Entry Probe Missions, The Planetary Science Journal 3.4 (2022) 98.</p> <p>[2] Hofstadter, M. et al., Uranus and Neptune missions: A study in advance of the next planetary science decadal survey, Planetary and Space Science 177 (2019) 104680.</p> <p>[3] National Academies of Sciences, Engineering, and Medicine. "Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032." (2022).</p>
Comet C/2002 T7 (LINEAR) was observed with the Microwave Instrument for Rosetta Orbiter (MIRO) on April 30, 2004, between 5 hr and 16 hr UT. The comet was 0.63AU distance from the Sun and 0.68AU distance from the MIRO telescope at the time of the observations. The water line involving the two lowest rotational levels at 556.936 GHz is observed at 557.070 GHz due to a large Doppler frequency shift. The detected water line spectrum is interpreted using a non local thermal equilibrium (Non-LTE) molecular excitation and radiative transfer model. Several synthetic spectra are calculated with various coma profiles that are plausible for the comet at the time of observations. The coma profile is modeled with three characteristic parameters: outgassing rate, a constant expansion velocity, and a constant gas temperature. The model calculation result shows that for the distant line observation where contributions from a large coma space is averaged, the combination of the outgassing rate and the gas expansion velocity determines the line shape while the gas temperature has a negligible effect. The comparison between the calculated spectra and the MIRO measured spectrum suggests that the outgassing rate of the comet is about 2.0x1029 molecules/second and its gas expansion velocity about 1.2 km/s at the time of the observations.
<p>In-situ probe measurements of planetary atmospheres add an immense value to remote sensing observations from orbiting spacecraft or telescopes, as highlighted and justified in numerous publications [1,2,3]. Certain key measurements such as the determination of noble gas abundances and isotope ratios can only be made in situ by atmospheric entry probes, but represent essential knowledge for investigating the formation history of the solar system as well as the formation and evolutionary processes of planetary atmospheres. Following the above rationale, a planetary entry mission to one of the outer planets (Saturn, Uranus and Neptune) has been identified as a mission of high priority by international space agencies. In particular, an entry probe mission proposal to Neptune has been selected as a flagship mission study in the next NASA decadal survey.</p><p>Within the scientific frame of atmospheric planetary sciences, a two- to three-year research study called IPED (<strong>I</strong>mpact of the <strong>P</strong>robe <strong>E</strong>ntry Zone on the Trajectory and Probe <strong>D</strong>esign) investigates the impact of the interplanetary and approach trajectories on the feasible range of atmospheric entry sites as well as the probe design, considering Saturn, Uranus and Neptune as target bodies. The objective is to provide a decision matrix for entry site selection by comparing several mission scenarios for different science cases.</p><p>In this presentation, the focus is on approach circumstances of the planetary entry probe upon arrival at a normalized, spherical planet. Science objectives are organised in four (planetocentric) latitude ranges: (1) low latitudes < 15&#176;, (2) mid latitudes between 15&#176; and 45&#176;, (3) high latitudes between 45&#176; and 75&#176; and (4) polar latitudes of > 75&#176;. The latitude ranges are considered as potential entry zones for the implementation. The implementation strategy will be explained and discussed. Astrodynamically accessible latitudes are presented as a function of the approach velocity&#160; vector v<sub>&#8734; </sub>(both declination of the approach asymptote and magnitude). A roadmap is shown that explains the next implementation step to include the physical characteristics of the destination planet such as the planet&#8217;s size, rotation period, shape, ring geometries and obliquity.</p><p>The presented research was supported by an appointment to the NASA Postdoctoral Program (NPP) at the Jet Propulsion Laboratory (JPL), California Institute of Technology, administered by Universities Space Research Association (USRA) under contract with National Aeronautics and Space Association (NASA). &#169; 2020 All rights reserved.</p><p>[1] Mousis, O. et al., Scientific Rationale for Saturn&#8217;s in situ exploration, Planetary and Space Science 104 (2014) 29-47.</p><p>[2] Mousis, O. et al., Scientific Rationale for Uranus and Neptune in situ explorations, Planetary and Space Science 155 (2018) 12-40.</p><p>[3] Hofstadter, M. et al., Uranus and Neptune missions: A study in advance of the next planetary science decadal survey, Planetary and Space Science 177 (2019) 104680.</p>
Aims. Using spectroscopic and continuum data measured by the MIRO instrument on board Rosetta of comet 67P/Churyumov-Gerasimenko, it is possible to derive and track the change in the water production rate, to learn how the outgassing evolves with heliocentric distance. The MIRO data are well suited to investigate the evolution of 67P, in unprecedented spatial and temporal detail.
