Spectral Rotational Characterization of the Didymos System prior to the DART Impact*

Ieva, S.; Epifani, E. Mazzotta; Perna, D.; Dall’Ora, M.; Petropoulou, V.; Deshapriya, J. D. P.; Hasselmann, P. H.; Rossi, Alessandro; Poggiali, Giovanni; Brucato, J. R.; Pajola, M.; Lucchetti, Alice; Ivanovski, Stavro; Palumbo, P.; Corte, Vincenzo Della; Zinzi, A.; Rivkin, A. S.; Thomas, C. A.; León, J. de; Dotto, E.; Amoroso, Marilena; Bertini, Ivano; Capannolo, Andrea; Cotugno, Biagio; Cremonese, G.; Tana, Valerio Di; Gai, Igor; Impresario, Gabriele; Lavagna, Michèle; Meneghin, Andrea; Miglioretti, Federico; Modenini, Dario; Pirrotta, Simone; Simioni, Emanuele; Simonetti, Simone; Tortora, Paolo; Zannoni, Marco; Zanotti, Giovanni

doi:10.3847/psj/ac7f34

Cited by 19 publications

(16 citation statements)

References 25 publications

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“…Variation of the reflectance spectra of the Didymos system might occur due to a color variation on Didymos's surface, regardless of the DART impact. Ieva et al (2022) reported a slope variation at the visible wavelength range, observed before the impact (on 2021 February). However, they could not correlate this variation with Didymos's rotation phases.…”

Section: Spectral Slope Variationmentioning

confidence: 97%

Near-IR Spectral Observations of the Didymos System: Daily Evolution Before and After the DART Impact Indicates that Dimorphos Originated from Didymos

Polishook,

DeMeo,

Burt

et al. 2023

Planet. Sci. J.

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Ejecta from Dimorphos following the DART mission impact significantly increased the brightness of the Didymos–Dimorphos system, allowing us to examine subsurface material. We report daily near-IR spectroscopic observations of the Didymos system using NASA’s IRTF that follow the evolution of the spectral signature of the ejecta cloud over 1 week, from 1 day before the impact. Overall, the spectral features remained fixed (S-type classification) while the ejecta dissipated, confirming that both Didymos and Dimorphos are constructed from the same silicate material. This novel result strongly supports binary asteroid formation models that include the breaking up of a single body due to rotational breakup of kilometer-wide bodies. At impact time +14 and +38 hr, the spectral slope decreased, but the following nights presented an increasing spectral slope that almost returned to the preimpact slope. However, the parameters of the 1 μm band remained fixed, and no “fresh”/Q-type-like spectrum was measured. We interpret this as follows. (1) The ejecta cloud is the main contributor (60%–70%) to the overall light during the ∼40 hr after impact. (2) Coarser debris (≥100 μm) dominated the ejecta cloud, decreasing the spectral slope (after radiation pressure removed the fine grains ≤10 hr after impact). (3) After approximately 1 week, the ejecta cloud dispersed enough to make the fine grains on Didymos’s surface the dominant part of the light, increasing the spectral slope to the preimpact level. (4) A negligible amount of nonweathered material was ejected from Dimorphos’s subsurface, suggesting that Dimorphos was accumulated from weathered material ejected from Didymos’s surface.

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Section: Spectral Slope Variationmentioning

confidence: 97%

Near-IR Spectral Observations of the Didymos System: Daily Evolution Before and After the DART Impact Indicates that Dimorphos Originated from Didymos

Polishook,

DeMeo,

Burt

et al. 2023

Planet. Sci. J.

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“…The mission targeted the secondary asteroid in an eclipsing binary system because the experiment could use a single impacting spacecraft and measure the change in the orbit of the secondary through ground-based observations. The Didymos system was selected as the target because it is among the most accessible (low Δ V ) of the near-Earth binaries, it has been extremely well characterized 4 – 6 , 8 – 12 and Dimorphos is in the size range identified as relevant for deflection by a kinetic impactor 13 , 14 .…”

Section: Mainmentioning

confidence: 99%

Orbital period change of Dimorphos due to the DART kinetic impact

Thomas

Naidu

Scheirich

et al. 2023

Nature

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The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision1, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement (β) was possible2,3. In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos4–6. Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be −33.0 ± 1.0 (3σ) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.

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“…Spectra indicate the presence heterogeneity of surface materials on Didymos, with various concentrations of probably hypersthene with a grain radius a < 25 μm, and olivine with a grain radius a < 45 μm (ref. 22 ). Laboratory simulations of space weathering showed that irradiation can cause significant reddening of olivine’s reflectance spectrum 23 .…”

Section: Mainmentioning

confidence: 99%

Light curves and colours of the ejecta from Dimorphos after the DART impact

Graykowski

Lambert

Marchis

et al. 2023

Nature

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On 26 September 2022, the Double Asteroid Redirection Test (DART) spacecraft struck Dimorphos, a satellite of the asteroid 65803 Didymos1. Because it is a binary system, it is possible to determine how much the orbit of the satellite changed, as part of a test of what is necessary to deflect an asteroid that might threaten Earth with an impact. In nominal cases, pre-impact predictions of the orbital period reduction ranged from roughly 8.8 to 17 min (refs. 2,3). Here we report optical observations of Dimorphos before, during and after the impact, from a network of citizen scientists’ telescopes across the world. We find a maximum brightening of 2.29 ± 0.14 mag on impact. Didymos fades back to its pre-impact brightness over the course of 23.7 ± 0.7 days. We estimate lower limits on the mass contained in the ejecta, which was 0.3–0.5% Dimorphos’s mass depending on the dust size. We also observe a reddening of the ejecta on impact.

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Spectral Rotational Characterization of the Didymos System prior to the DART Impact*

Cited by 19 publications

References 25 publications

Near-IR Spectral Observations of the Didymos System: Daily Evolution Before and After the DART Impact Indicates that Dimorphos Originated from Didymos

Near-IR Spectral Observations of the Didymos System: Daily Evolution Before and After the DART Impact Indicates that Dimorphos Originated from Didymos

Orbital period change of Dimorphos due to the DART kinetic impact

Light curves and colours of the ejecta from Dimorphos after the DART impact

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