The Near-Nucleus Coma Formed by Interacting Dusty Gas Jets Effusing from a Cometary Nucleus: I

Crifo, J. F.; Itkin, A. L.; Родионов, А. В.

doi:10.1006/icar.1995.1114

Cited by 33 publications

(27 citation statements)

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“…Planar gas shocks seen edge-on may be mistaken for a jet (Crifo et al, 1995). In the same way, very small dust grains can become so entrained in the gas flow that they also exhibit density enhancements along the shocks (e.g., Combi et al, 1997), which can mimic dust jet structure (though larger grains can pass through the shocks unaffected).…”

Section: Hydrodynamic Interactionsmentioning

confidence: 99%

“…Gombosi and Horanyi, 1986;Combi, 1996), which showed that shell structures can be produced by modulation of the gas production. Investigations of the interactions between two or more jets (Kitamura, 1990;Crifo et al, 1995) showed that planar shocks result, with a corresponding increase in the density in the interacting region. Similar studies of the dust and gas (e.g.…”

Section: Hydrodynamic Interactionsmentioning

confidence: 99%

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Coma morphology of Jupiter-family comets

Farnham

2009

Planetary and Space Science

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We present a general review of cometary coma morphology, with specific reference to how it used in studies of Jupiter family comets. We introduce the most common features that are seen in gas and dust observations, and summarize of how they are used to infer the properties of the nucleus and coma. We also expand the discussion to cover other topics relating to morphology, including the general shape of the coma (characterized by radial gradient profiles) and spatial maps of the color, albedo and polarization of the dust. We address the pros and cons of the different approaches used in the interpretation and analysis of the features. Finally, we review the results obtained for specific comets and compare the Jupiter family comets to those from other classes.

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Section: Hydrodynamic Interactionsmentioning

confidence: 99%

Section: Hydrodynamic Interactionsmentioning

confidence: 99%

Coma morphology of Jupiter-family comets

Farnham

2009

Planetary and Space Science

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“…Shocks deflect flows somewhat (Crifo & Rodionov 1997a), but can also be described as largely directed away from the nucleus. However, very close to the comet surface and away from the subsolar region, the gas velocity can be almost tangential to a spherical nucleus surface (Crifo et al 1995), becoming radial first at a few nucleus radii. ---) and its ratio to the lift coefficient, η (--), as functions of the flow-surface angle θ (see text), and the coma temperature T .…”

Section: Aerodynamic Forcesmentioning

confidence: 99%

On the dynamical stability of the Rosetta orbiter. I.

Mysen

Aksnes

2006

A&A

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The Rosetta probe is to monitor, from a bound orbit, its primary target comet 67P/Churyumov-Gerasimenko for extended periods of time. As a preliminary assessment of the challenges involved, the strengths of the effects which perturb the spacecraft's cometocentric Keplerian trajectory are evaluated. It is found that in our adopted nominal scenario, where the CO outgassing rate is set to one tenth of its upper limit, motion could be considered regular a long time after rendezvous. Furthermore, in this weak limit, gravity perturbations have a negligible destabilizing effect on the shape of the orbit, while the secular impact risk under the effect of radiation pressure is minimized by placing the orbit in the plane normal to the cometocentric direction of the Sun, with a low initial eccentricity. The comet's heliocentric distance for probe escape for an orbit started in the solar plane-of-sky, however, is seen to be dependent on the initial semi-major axis only, and linearly so. In order to calculate the dynamical effects of outgassing, a radially directed, asymmetric and periodically time-varying pressure field is adopted. Accordingly, it is shown that specific field asymmetries, related to the tendency of the outgassing field to "remember" the direction of comet motion, represent the extreme scenarios as far as orbital stability for the full problem is concerned.

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“…If not very close to the nucleus, where the flow could be almost along the comet surface (Crifo et al 1995), u/v = r/r is a common assumption. This is related to the fact that while the cometocentric velocity of a probe in a bound orbit is ∼0.1 m s −1 , the velocity of the collisionally accelerated outflowing molecules could typically be as high as ∼1 km s −1 (Crifo & Rodionov 1997).…”

Section: Outgassing Pressurementioning

confidence: 99%

The Jacobi constant for a cometary orbiter

Mysen

Aksnes

2005

A&A

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The Jacobi constant of a probe under the gravitational attraction of a rotating irregular body is rederived for excited, but free rigid rotation of the central mass. A related Tisserand-like quantity is found to be sufficiently conserved for it to qualify as a pseudo-integral. The quantity's near constancy is shown to imply that certain regions in the space of the probe's cometocentric orbital elements are forbidden. In particular, based solely on this analysis, it is seen how collision with the comet nucleus is best avoided if the initial probe velocity lies in the plane normal to the nucleus' rotational spin. A conclusion which is of relevance to the Rosetta mission where the lander Philae is to be delivered by Rosetta in a possibly close prograde, and therefore probably shape unstable, orbit. At the comet's heliocentric distance when the lander is delivered, radiation and radial outgassing pressure do not significantly affect these conclusions for a nominal target nucleus in a worst-case scenario. The latter effect is seen to somewhat decrease the impact risk of prograde trajectories, making the more stable retrograde orbits slightly less safe.

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The Near-Nucleus Coma Formed by Interacting Dusty Gas Jets Effusing from a Cometary Nucleus: I

Cited by 33 publications

References 0 publications

Coma morphology of Jupiter-family comets

Coma morphology of Jupiter-family comets

On the dynamical stability of the Rosetta orbiter. I.

The Jacobi constant for a cometary orbiter

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