A comet nucleus sample return mission

Feingold, H.; Hoffman, Stephen J.; Soldner, J. K.

doi:10.2514/6.1984-2027

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…Compilations of multi-wavelength constraints on individual comets to determine their nucleus radius include C/1995 O1 (Hale-Bopp) (Weaver and Lamy 1997;Fernández 2002) and C/1983 H1 (IRAS-Araki-Alcock) (Groussin et al 2010). Non-gravitational accelerations (caused by momentum transfer to the nucleus from outgassing materials) from orbit calculations and overall brightness have been used to infer mass (e.g., Rickman 1986Rickman , 1989Fernández 2009, 2011). When sizes are also known, this can also yield estimates of the bulk density of the nucleus (e.g., Farnham and Cochran 2002;Davidsson and Gutiérrez 2006).…”

Section: Other Methods Of Constraining Nucleus Propertiesmentioning

confidence: 99%

Observations of Comet Ison (C/2012 S1) From Lowell Observatory

Knight

Schleicher

2014

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We observed the dynamically new sungrazing comet ISON (C/2012 S1) extensively at Lowell Observatory throughout 2013 in order to characterize its behavior prior to perihelion. ISON had "typical" abundances for an Oort Cloud comet. Its dust production, as measured by r Af , remained nearly constant during the apparition but its CN gas production increased by ∼50 ×. The minimum active area necessary to support observed water production rates exceeded the likely surface area of the nucleus and suggests a population of icy grains in the coma. Together with the flattening of the dust radial profile over time, this is consistant with ejection of a large quantity of slow moving dust and icy grains in the coma at large heliocentric distance. The dust morphology was dominated by the tail, but a faint sunward dust fan was detected in March, April, May, and September. We imaged multiple gas species in September, October, and November. All gas species were more extended than the dust coma, although only CN had sufficient signal-to-noise for detailed morphological study. Excess CN signal was observed in the sunward hemisphere in September and early October. In November the excess CN signal was in the tailward hemisphere and two faint CN features appeared approximately orthogonal to the tail with position angles varying by about ±20°from night to night. Using numerical modeling, we best reproduced the orientation and shape of these features as well as the bulk brightness with a pole oriented approximately toward the Sun and a single source located within ∼35°of the equator. Variations in position angle and relative brightness of the CN features from night to night suggest a rotation period shorter than 24 hr. The production rates and coma morphology suggest a nucleus that was active over nearly its entire sunward facing hemisphere in September and October but which underwent a significant mass loss event, potentially including fragmentation, shortly before November 1. Significant subsequent mass loss likely continued at the same site over subsequent days/weeks and may have catastrophically weakened the nucleus prior to perihelion.

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Section: Other Methods Of Constraining Nucleus Propertiesmentioning

confidence: 99%

Observations of Comet Ison (C/2012 S1) From Lowell Observatory

Knight

Schleicher

2014

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“…Wechsler assumes the same reliability over the entire range of scores for each subtest within each age group, although the reliability is likely to vary between score levels. Further, Wechsler's reliabilities are based on raw scores, not the generally less variable scaled scores, and are, therefore, spuriously high (Feingold, 1984). Thus, Wechsler's standard errors, which are calculated from those reliabilities and the standard deviations of scaled scores, are probably too small.…”

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Confidence intervals for true scores and retest scores on clinical tests

Brophy¹

1986

J. Clin. Psychol.

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Procedures are described for setting confidence intervals for a true score and a retest score given an obtained score. The confidence intervals are functions of the estimated true score (not the obtained score) and either the standard error of the true score or the standard error of estimate of the retest score. Errors that result from the customary but incorrect use of confidence intervals are analyzed for IQ scores on the Wechsler Intelligence Scale for Children‐Revised and the Wechsler Adult Intelligence Scale‐Revised. Simple equations are given to establish confidence intervals for scores on any test.

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A comet nucleus sample return mission

Cited by 2 publications

References 2 publications

Observations of Comet Ison (C/2012 S1) From Lowell Observatory

Observations of Comet Ison (C/2012 S1) From Lowell Observatory

Confidence intervals for true scores and retest scores on clinical tests

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