Abstract
Radar and spacecraft observations show the permanently shadowed regions around Mercury’s North Pole
to contain water ice and complex organic material. One possible source of this material are impacts by
interplanetary dust particles (IDPs), asteroids, and comets.
We have performed numerical simulations of the dynamical evolution of asteroids and comets over the few
Myr and checked for their impacts with Mercury. We use the N-body integrator RMVS/Swifter to propagate
the Sun and the eight planets from their current positions. We add comets and asteroids to the simulations as
massless test particles, based on their current orbital distributions. Asteroid impactors are assigned a probability
of being water-rich (C-class) based on the measured distribution of taxonomic types. For comets, we assume a
constant water fraction. For IDPs, we use a dynamical meteoroid model to compute the dust flux on Mercury.
Relative to previous work on asteroid and comet impacts (Moses et al., 1999), we leverage 20 years of progress
in minor body surveys.
Immediate post-impact ejection of impactor material into outer space is taken into account as is the
migration efficiency of water across Mercury’s surface to the polar cold traps.
We find that asteroids deliver ∼ 1 × 103 kg/yr of water to Mercury, comets deliver ∼ 1 × 103 kg/yr and IDPs
deliver ∼ 16 × 103 kg/yr within a factor of several. Over a timescale of ∼ 1Gyr, this is enough to deliver the
minimum amount of water required by the radar and MESSENGER observations.
While other sources of water on Mercury are not ruled out by our analysis, we show that they are not
required to explain the currently available observational lower limits.
to contain water ice and complex organic material. One possible source of this material are impacts by
interplanetary dust particles (IDPs), asteroids, and comets.
We have performed numerical simulations of the dynamical evolution of asteroids and comets over the few
Myr and checked for their impacts with Mercury. We use the N-body integrator RMVS/Swifter to propagate
the Sun and the eight planets from their current positions. We add comets and asteroids to the simulations as
massless test particles, based on their current orbital distributions. Asteroid impactors are assigned a probability
of being water-rich (C-class) based on the measured distribution of taxonomic types. For comets, we assume a
constant water fraction. For IDPs, we use a dynamical meteoroid model to compute the dust flux on Mercury.
Relative to previous work on asteroid and comet impacts (Moses et al., 1999), we leverage 20 years of progress
in minor body surveys.
Immediate post-impact ejection of impactor material into outer space is taken into account as is the
migration efficiency of water across Mercury’s surface to the polar cold traps.
We find that asteroids deliver ∼ 1 × 103 kg/yr of water to Mercury, comets deliver ∼ 1 × 103 kg/yr and IDPs
deliver ∼ 16 × 103 kg/yr within a factor of several. Over a timescale of ∼ 1Gyr, this is enough to deliver the
minimum amount of water required by the radar and MESSENGER observations.
While other sources of water on Mercury are not ruled out by our analysis, we show that they are not
required to explain the currently available observational lower limits.
| Original language | English |
|---|---|
| Article number | 114980 |
| Pages (from-to) | 1-11 |
| Number of pages | 11 |
| Journal | Icarus |
| Volume | 383 |
| DOIs | |
| Publication status | Published - 1 Sept 2022 |
Bibliographical note
Funding Information:We are thankful to David E. Kaufmann for valuable help with RMVS/Swifter, Cecile Engrand and Mikhail Zelensky for input on the water fraction of IDPs. This research has made use of data and/or services provided by the International Astronomical Union’s Minor Planet Center. We would like to thank the Center for Information Technology of the University of Groningen for their support and for providing access to the Peregrine high performance computing cluster. Petr Pokorný’s work was supported by NASA awards number 80GSFC21M0002 and 80NSSC21K0153 . The authors thank the two anonymous reviewers for their thoughtful comments, which significantly improved the manuscript.
Funding Information:
This paper is dedicated to the brave resistance of Ukrainian people. We are thankful to David E. Kaufmann for valuable help with RMVS/Swifter, Cecile Engrand and Mikhail Zelensky for input on the water fraction of IDPs. This research has made use of data and/or services provided by the International Astronomical Union's Minor Planet Center. We would like to thank the Center for Information Technology of the University of Groningen for their support and for providing access to the Peregrine high performance computing cluster. Petr Pokorný’s work was supported by NASA awards number 80GSFC21M0002 and 80NSSC21K0153. The authors thank the two anonymous reviewers for their thoughtful comments, which significantly improved the manuscript.
Publisher Copyright:
© 2022 Elsevier Inc.
Keywords
- Asteroids, dynamics
- Astrobiology
- Comets, dynamics
- Interplanetary dust
- Mercury, surface