JuanCastillo29/space-mission-intelligence-data huggingface dataset:
arycentric Positions (m) Velocities (m/d) Interval A B A B Mercury 3500 4600 260 280 Venus 1700 2500 37 41 EMB 760 4000 11 48 Mars 980 14000 9 140 Jupiter 240000 1300000 350 1900 Saturn 320000 560000 161 320 Uranus 1800000 1800000 290 410 Neptune 2400000 7500000 320 620 Pluto 7500000 140000000 1700 7200]

the Mars Express and Venus Express tracking data processed by ESA and normal points deduced from the Cassini mission. Thanks to these data, large improvements were made in the determination of the orbits of Venus and Saturn. They open doors to new tests of gravity which were hitherto limited to only Earth-Mars distance accurate observations. These tests and their results will be presented in a dedicated paper very soon. However, as was already stressed in section 5.1.1, VEX tracking data and Saturn Cassini normal points have a crucial role to play in such investigations. The LLR data have been used for the adjustment of the lunar orbit and libration in INPOP08 (Manche et al. 2007). The fit to these data as well as the complete lunar model will be described in a forthcoming paper. The INPOP08 planetary ephemeris is available for users on the INPOP website (www.imcce.fr/inpop) as Chebychev polynomials coefficients interpolated via provided routines in C and fortran. Positions and velocities of the nine planets, the Sun, the moon libration and the 3 Euler angles of the Earth rotation can be extracted as well as the TT-TDB relation at any time. An alternative version with rescaled GM of the sun and AU fixed is also provided on request. In the next version, we plan to adjust directly the GM of the sun instead of the AU. Simulations of Mercury missions data and use of fly-by data will be introduce in order to evaluate the improvements in terms of accuracy limits in the determination of PPN parameters and J2.

[Table: Table 6. Maximum differences between DE421 and INPOP08 estimated on interval A from 1990 to 2010 and on interval B from 1900 to 2050.
Barycentric Barycentric Positions (m) Velocities (m/d) Interval A B A B Mercury 3900 4400 290 310 Venus 740 3200 13 39 EMB 870 3900 11 36 Mars 1300 9200 10 82 Jupiter 210000 1300000 290 2000 Saturn 35000 40000 22 23 Uranus 1400000 2500000 190 390 Neptune 3700000 14000000 480 1200 Pluto 4300000 120000000 830 6700]
arycentric Positions (m) Velocities (m/d) Interval A B A B Mercury 3900 4400 290 310 Venus 740 3200 13 39 EMB 870 3900 11 36 Mars 1300 9200 10 82 Jupiter 210000 1300000 290 2000 Saturn 35000 40000 22 23 Uranus 1400000 2500000 190 390 Neptune 3700000 14000000 480 1200 Pluto 4300000 120000000 830 6700]

Acknowledgements. We thank S. Klioner for multiple dicussions during this work and M. Standish for constructive comments. This work was supported by CNES under contract 05/CNES//00-DCT 094, by the CS of Paris Observatory, and by PNP-CNRS.
which will require at least five years of continuous observations for Jupiter orbit. For Mars and the EMB, one can see on figure 7 the differences are also reduced between DE421 and INPOP08 compared to the differences obtained between INPOP06 and INPOP08. As well for the EMB in table 5, if one uses the differences between ephemerides as a tool to estimate ephemerides accuracy, the uncertainties on its barycentric positions are about 900 meters over 10 years and 4 kilometers over 100 years, and about 10 meters per day to 50 meters per day for its barycentric velocities.
References Baer, J., Chesley, S. R. 2008, Celestial Mechanics and Dynamical Astronomy, 100, 27 Baer, J., Milani, A., Chesley, S., Matson, R. D. 2008, AAS/Division for Planetary Sciences Meeting Abstracts, 09-28, 40 Budnik, F., Morley, T. A. and Mackenzie, R. A. 2004, ESA SP, 548, 387 Damour, T., & Vokrouhlick´y, D. 1995, Physical Review D, 52, 4455 Damour, T.,Soffel, M., Xu, C. 1991, Phys. Rev. D, 43, 3273 Fairhead, L. Bretagnon, P. 1990, A&A, 229, 240 Fienga, A., Manche, H., Laskar, J.,Gastineau, M. 2008, A&A, 477, 315 Folkner, W.M. 2008, JPL Interoffice Memorandum, 343R, 08 Irwin, A. W., Fukushima, T. 1999, A&A, 348, 642 Hilton, J. L. 1999, AJ, 117, 1077 IERS Conventions 2003, 2004, IERS Technical Note, 32, Frankfurt am Main: Verlag des Bundesamts fur Kartographie und Geodesie Klioner, S. A.2007private communication. Klioner, S. A. 2008, IAU Symposium, 248, 356
7. Perspectives and conclusions In this article, INPOP08 was fully described as a new 4-D planetary ephemeris. New modeling of asteroid perturbations were introduced and as described by Kuchynka et al. (2009), improvements in the methods of asteroid mass determinations are possible. Introduction of these new methods will be done in the next INPOP version, leading to an improvement of the extrapolation capabilities of the ephemerides as well as more realistic determination of asteroid masses.

[Figure: Fig. 7. Differences between INPOP08 and INPOP06 (left-hand side) and between INPOP08 and DE421 (right-hand side). For each planet, comparisons are made on the heliocentric longitude (barycentric for the Sun), expressed in the ecliptic frame. Units are milliarcseconds for Y-axis and years around J2000 for X-axis.]
ations are possible. Introduction of these new methods will be done in the next INPOP version, leading to an improvement of the extrapolation capabilities of the ephemerides as well as more realistic determination of asteroid masses.

[Figure: Fig. 7. Differences between INPOP08 and INPOP06 (left-hand side) and between INPOP08 and DE421 (right-hand side). For each planet, comparisons are made on the heliocentric longitude (barycentric for the Sun), expressed in the ecliptic frame. Units are milliarcseconds for Y-axis and years around J2000 for X-axis.]

Konopliv, A. S., Yoder, C. F., Standish, E. M., Yuan, D.-N., Sjogren, W. L. 2006, Icarus, 182, 23 Kuchynka, P., Laskar, J., Fienga, A., Manche, H., Somenzi, L. 2009, JOURNEES-2008/ Astrometry, Geodynamics and Astronomical Reference Systems, ed. M. Soffel, N. Capitaine. , Dresden Manche, H., Bouquillon S., Fienga A., Laskar J., Francou G. 2007, JOURNEES-2007/The Celestial Reference Frame for the Future , ed. N. Capitaine. , Paris Michalak, G. 2000, A&A, 360, 363 Moyer, T. 2000, ed. Joseph H. Yuen, John Wiley & Sons, Moyer, T. 1971, Technical report 32-1527 , JPL, May 15 Morley, T. 2006a, 2007a, 2007b, MEX data release Morley, T. and Budnik, F. 2007, Proceedings 20th International Symposium on Space Flight Dynam- ics, Annapolis, MD Pitjeva, E. V. 2008, JOURNEES-2008: Astrometry, Geodynamics and Astronomical Reference Systems, ed. M. Soffel, N. Capitaine. , Dresden Soffel, M., Klioner, S. A., Petit, G., Wolf, P., Kopeikin, S. M., Bretagnon, P., Brumberg, V. A., Capitaine, N., Damour, T., Fukushima, T., Guinot, B., Huang, T.-Y., Lindegren, L., Ma, C., Nordtvedt, K., Ries, J. C., Seidelmann, P. K., Vokrouhlick, D., Will, C. M., Xu, C. 2003, Astron. J., 126, 2687 Somenzi, L., Fienga, A., Laskar, J. 2009, A&A, submitted, Standish, E.M. 1998a, A&A, 336, 381 Standish, E.M. 1998b, JPL Interoffice Memorandum, 312.F, 98 Standish, E. M., Williams, J.G. 2001, ftp://ssd.jpl.nasa.gov/pub/eph/planets/ioms/, ExplSupplChap8.pdf, Standish, E. M. 2006, JPL Interoffice Memorandum, 343R-06-002, 1 Tedesco, E. F., Cellino, A., & Zappal´a, V. 2005, AJ, 129, 2869
Xiang Tang ,1, 2 Xian Shi ,1 and Mohamed Ramy El-Maarry 1Shanghai Astronomical Observatory, Chinese Academy of Sciences 80 Nandan Road, 200030 Shanghai, China 2School of Astronomy and Space Sciences, University of Chinese Academy of Sciences 19A Yuquan Road, Beijing 100049, China 3Khalifa University of Science and Technology P.O. Box: 127788, Abu Dhabi, UAE
(Accepted 2024 Nov) ABSTRACT European Space Agency’s Rosetta mission is the only space mission that performed long-term monitoring of comet at close distances. Its over two years’ rendezvous with comet 67P/Churyumov-Gerasimenko revealed diverse evolutionary processes of the cometary nucleus. One of the most striking events is the migration of a ∼30-m boulder in the southern hemisphere region of Khonsu. Previous works found the boulder’s ∼140-m displacement occurred during the three months from August to October 2015, and several triggering mechanisms were proposed, including outburst at the boulder site, seismic vibrations from nearby activities, or surface erosion of the slope beneath the boulder. In this work, we further analyze this impressive event by analysing imaging data from Rosetta’s OSIRIS camera. We constrained the boulder’s migration time to within 14 hours and derived a detailed timeline of the boulder migration event and local dust activities. High-resolution thermophysical modelling shows significant dichotomy in the thermal history of the boulder’s southern and northern sides, which could have triggered or facilitated its migration via its own volatile activity.
Keywords: Comet nuclei, Comet surfaces, Comet activity 1. INTRODUCTION European Space Agency’s Rosetta mission acquired vast amount of high resolution data from close proximity that reveal the evolution of a comet during its over two-years’ operation around comet 67P/Churyumov-Gerasimenko (hereafter 67P) (Taylor et al. 2017). Comet 67P is a Jupiter-family comet that orbits the Sun every ∼6.5 years. It has a bi-lobed shape consisting of a ∼3 km body and a ∼2 km head connected by a narrow neck (Sierks et al. 2015). One of the most significant findings by Rosetta is the intricate interplay between the cometary nucleus and its coma. The nucleus, being
Corresponding author: Xian Shi shi@shao.ac.cn 2 the source of gas and dust coma, is simultaneously being replenished and reshaped by coma materials (Thomas et al.
ion (2015 August 13, rh = 1.243AU) (Hasselmann et al. 2019). The migrated boulder was first reported by El-Maarry et al. (2017), who narrowed the time of the migration to between 2015 August 1 and October 30. Hasselmann et al. (2019) estimated the activity time to within two months after 67P’s perihelion (Figure 2). The triggering mechanism of such event 3 remains not well understood, while nominal water ice activity should not be sufficient to mobilize such massive boulder.

Several hypotheses were proposed to explain the boulder’s destabilisation, including: an outburst that directly lifted or pushed the boulder, the erosion of the sloped surface where the boulder resided, or a local seismic vibration from an active source. Among them, the most commonly agreed one is that an outgassing from the boulder’s original location or in the neighboring areas, exerted a force on the boulder and triggered its roll downslope (El-Maarry et al. 2017; Hasselmann et al. 2019).

[Figure: Figure 1. High-resolution images and Shape model of the boulder and its surrounding areas. In images, the arrows point to the boulder at that time and the red cross marks the original position of boulder in the ‘after’ image, the dates are the image acquisition time. (a) Local shape model showing the boulder at both locations before and after the migration. Red area covers the localized shape model used for thermal analysis. (b) Location of the Khonsu region (outlined in dashed red line) on the large lobe of the nucleus. Blue area is as shown in decimated shape model a.]

In this work we further investigate this boulder migration event, aiming to determine the time and condition of the movement, together with its potential link to local dust activity. Moreover, by modeling the thermal history of the boulder and its surrounding areas, we discuss possible mechanism for its mobilisation and the implications on cometary material redistribution.
2. OBSERVATIONS We utilise observations acquired by Rosetta’s scientific camera system OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) (Keller et al. 2007). OSIRIS consists of one Narrow Angle Camera (NAC) and one Wide Angle Camera (WAC) with field of view of 2.2◦× 2.2◦and 4 11.6◦× 11.6◦, respectively.

They acquired image sequences of 67P’s nucleus and its surrounding coma with different operation modes fulfilling designated science objectives (Sierks et al. 2015). We used the Level 3 (CODMAC Level 4) imaging data with same filters and similar exposure times. The images were geometrically and radiometrically calibrated, and archived in PDS format (Tubiana et al. 2015). For determining a timeline of the event, we searched through OSIRIS database with the help of ESA’s Planetary Science Archive(PSA, https://archives.esac.esa.int/psa/). A candidate catalog of images was first built by filtering out images that cover the region of interest within the time range of the boulder migration. We then select from the catalog images that display the surface area containing the boulder with favorable viewing geometries. Key images used in this study are listed in Table 1.
and radiometrically calibrated, and archived in PDS format (Tubiana et al. 2015). For determining a timeline of the event, we searched through OSIRIS database with the help of ESA’s Planetary Science Archive(PSA, https://archives.esac.esa.int/psa/). A candidate catalog of images was first built by filtering out images that cover the region of interest within the time range of the boulder migration. We then select from the catalog images that display the surface area containing the boulder with favorable viewing geometries. Key images used in this study are listed in Table 1.

[Table: Table 1. Information of selected OSIRIS image data for this study.
Sequence(s) (UTC) Sun lat(°) Sun lon(°) rh (AU) α(°) d(km) Res.(m px−1) NAC 2015-03-25, 19:00 15.0 232.6 2.01 72.8 83.0 1.544 NAC 2015-05-02, 15:09 3.0 208.8 1.73 60.5 124.9 2.323 NAC 2015-05-23, 21:51 -5.7 184.9 1.57 61.8 159.3 2.963 NAC 2015-09-26, 06:00 -48.9 328.6 1.36 53.4 771.3 14.347 NAC 2015-10-03, 09:26 -46.7 303.6 1.39 52.3 1072.9 19.956 NAC 2015-10-03, 19:30 -46.6 6.4 1.39 52.7 1021.1 18.992 NAC 2015-10-03, 22:49 -46.6 268.0 1.39 52.9 1004.1 18.676 NAC 2015-10-04, 19:01 -46.3 30.9 1.40 54.0 903.0 16.797 NAC 2015-10-04, 19:21 -46.3 20.9 1.40 54.0 901.4 16.766 NAC 2015-10-04, 19:41 -46.3 11.1 1.40 54.0 899.8 16.736 NAC 2015-10-04, 20:01 -46.3 1.3 1.40 54.1 898.1 16.705 NAC 2015-10-04, 20:21 -46.3 351.3 1.40 54.1 896.5 16.675 NAC 2015-10-04, 21:18 -46.2 323.4 1.40 54.2 891.9 16.589 NAC 2015-10-09, 09:39 -44.7 357.3 1.42 59.9 580.2 10.792 NAC 2015-12-13, 01:14 -22.0 334.1 1.87 89.3 101.0 1.879 NAC 2016-02-07, 13:10 -7.8 220.9 2.31 59.2 47.0 0.875 NAC 2016-02-10, 13:23 -7.2 226.3 2.33 65.1 49.8 0.925 NAC 2016-08-15, 11:19 16.86 228.9 3.58 89.0 8.9 0.166]
87 89.3 101.0 1.879 NAC 2016-02-07, 13:10 -7.8 220.9 2.31 59.2 47.0 0.875 NAC 2016-02-10, 13:23 -7.2 226.3 2.33 65.1 49.8 0.925 NAC 2016-08-15, 11:19 16.86 228.9 3.58 89.0 8.9 0.166]

Note—Column description: acquisition date of the NAC images, sub-solar point latitude and longitude, 67P heliocentric distance (rh), phase angle (α), spacecraft-comet distance (d) and surface resolution.
It is worth mentioning that, OSIRIS images taken during the time of interest are of significantly varying resolutions. At the beginning of 2015 October, Rosetta performed an excursion to the comet tail when the spacecraft reached as far as over 1500 km away from the nucleus (Figure 2). As illustrated in Figure 3, NAC image taken on 2015 September 26 at a distance of ∼771 km yields a surface resolution of ∼14.347 m px−1, compared to ∼0.166 m px−1 of that image taken on 2016 August 15. During Rosetta’s extended mission after perihelion, the spacecraft rendezvoused with the 5 comet at closer distances, enabling us to investigate comet surface features in detail, including the boulder and its surrounding environment after the migration event.

[Figure: Figure 2. Variations of sub-solar point latitude (degree), 67P’s heliocentric distance (AU), spacecraft-comet distance (km) and NAC image spatial resolution (m pixel−1) for the time period between September 2014 and August 2016. The grey-outlined box indicates the time span of data used in this study. The red-dashed boxes with time annotations, Time[1] and Time[2], represent the proposed migration time for the boulder in El-Maarry et al. (2017) and Hasselmann et al. (2019), respectively. The perihelion passage and excursion period are present in vertical line.]

[Figure: Figure 3. Comparison of NAC surface resolution with Rosetta at different distances to the nucleus. NAC captured two images in different time. The image in rich detail was taken after perihelion while another showing the spacecraft was traveling away from 67P. The axes are set in logarithm scale.]
Fe Ca O
Accretion
Photosphere
Visible in absorption
WD interior
Sinking

[Figure: Fig. 6 Stages in the delivery of small bodies to WDs (A–D), along with observational evidence for each stage (E–H). Observations shown are: (E) False-positive Super-Jovian planetary candidate companion to WD 2105-82 imaged at 15 microns with JWST/MIRI (Mullally et al, 2024, Fig. 1∗); (F) Deep, asymmetric occultations by material on long-period, possibly eccentric orbit around ZTF J0139+52 (Figure courtesy Zach Vanderbosch, based on Vanderbosch et al, 2020, Fig. 1); (G) Decrease with time in the 3- and 5-micron IR flux excess (Spitzer/IRAC and JWST/NIRSpec) of WD 0145+234, possibly due to collisional evolution of the dust disc (Swan et al, 2024, Fig. 1∗); (H) Spectroscopically-inferred abundances of material accreted onto 7 WDs, compared to Solar System bodies (Swan et al, 2023, Fig. 1∗). ∗Reproduced under the CC-BY-4.0 license https://creativecommons.org/licenses/by/4.0/]
original image cannot directly provide detect any clues for the migration event. Though this image actually recorded information of local dust activities (see subview in Figure 4b, and Sec. 3.3). Another image acquired later at 21:18 on October 4 shows the area under favourable illumination (Figure 4d), and the boulder could be confirmed to be unmistakably at its new location.
3.2. Boulder and its surroundings 9 We compare pairs of images with similar observation geometry acquired before and after the migration event to investigate changes in the morphology and positions of the boulder and its surroundings (Figure 5).

[Figure: Figure 4. OSIRIS observations of the boulder location in early-October of 2015. During this time period images capturing from far distances, we utilized the zoom-in views (second column) and synthetic views (right column) of the observations for comparison. Images with round labels are observations of the boulder before its migration, in which (a) the last image showing that the boulder at its original position. (b) The only image captured during boulder’s migration (with green label). The circles mark the position of boulder before and after its migration. The position of the boulder cannot be identified as a result of unclear lighting condition. For comparison, in the bottom right in b0 is the contrast-stretched view of the actual image. The square image labels represent post-migration observations of the boulder, where (c) fairly low-resolution showing the boulder at its new position, (d) an image of the first confirmation for the migrated boulder. Red arrows and red hollow cross mark the original location of the boulder, green arrows point to the boulder after its migration and orange dash lines identify the “pancake” feature.]

[Figure: Figure 5. OSIRIS observations of the boulder and its surroundings. Yellow arrows highlight the cluster of small boulder, the shallow scarp, the cluster of outcrop, situated to the north, west and east of the boulder’s former location, respectively. Yellow circles mark the presence of the isolated small boulder, and rectangles mark a lumpy relief in the possible route of migration. (a) side view observation of Khonsu region with the best spatial resolution before perihelion. (b) front view of boulder’s neighbouring areas. (c) observation of post-perihelion morphological state of local region from side view. (d) front view for inspecting the boulder’s surrounding after perihelion. Red arrows and red hollow cross mark the original location of the boulder, green arrows point to the boulder after its migration and orange dash lines identify the “pancake” feature.]
northern side. Intriguingly, the southern side of the boulder was subject to constant illumination before the migration event, with some of the facets experiencing constant illumination over more than 150 rotations (Figure 8b).

[Figure: Figure 8. Insolation history of the boulder and its surrounding areas before its migration. (a) cumulative insolation between 2014-05-17 and 2015-10-03; The locations of representative facets S and N are indicated with red and blue crosses, respectively; (b) number of rotations with constant illumination, or ‘polar days’, for each facet.]

For quantitative comparison, we chose two representative facets, facet S on the southern side of the boulder and facet N on the northern side, and modelled the thermal evolution of the top meter of the nucleus at these two facets over both one rotation and one orbit. The diurnal thermal variation was simulated starting at Oct 3 UTC 10:00 to cover the possible migration time of the boulder. Temperatures in the top 1 cm of facet S stayed above 230 K throughout one nucleus rotation, while reaching a maximum of ∼330 K (Figure 9a) at ∼UTC 15:00 on October 3. The diurnal variation of temperature gradually attenuated with increasing depth. At ∼1 cm depth, roughly where the diurnal heat wave can penetrate, the temperature undulates around 246 ± 5 K, which is still significantly higher than the general sublimation temperature of water ice. On the contrary, facet N on the north face experienced relatively short daytime and received much less energy, resulting in lower temperatures at all depths (Figure 9b). The surface temperature did not exceed 200 K over the entire rotation, while staying below 170 K for 70% of the time. Note that the surface temperature of facet N peaks at an earlier time than facet S, roughly around UTC 12:00. On orbital time scale, the dichotomy is even more evident. Figure 9 c&d show variation of temperatures at depths from one centimeter to one meter at the two facets over one orbital period of 14 6.45 years.
release large quantity of dust particles, that could transiently increase the brightness of the coma significantly. For comparison, the gas production rate of the outburst on 2016 February 19 is estimated to be 10 kg·s−1 (Gr¨un et al. 2016), and it caused an increase in the brightness of 67P’s coma by two orders of magnitude (Figure 4 in Gr¨un et al. (2016)). Since the brightness surge usually lasts for less than half an hour, and given the sparse observations at the time, we are not able to conclude at different depths of (a)

[Figure: Figure 9. Depth-dependent temperature variation at two facets on the southern and northern sides of the boulder during one rotation and one orbit of 67P. (a) Diurnal temperature variation at different depths of facet S from 2015-10-03T10:00:00; (b) the same as (a) for facet N; (c) Orbital temperature variation at different depths of facet S; (d) the same as (c) but for facet N. Vertical gray line indicates the time of the boulder migration.]

[Figure: Figure 10. Flux rate of water vapour during one rotation of the nucleus starting from 2015-10-03T10:00:00]

facet S and (b) facet N whether such an outburst did occur within the 14 hour window of the migration event. Outbursts 16 are also commonly accompanied by surface changes, often revealing more pristine subsurface with higher ice content.