Detection of water in the LCROSS ejecta plume

Science

Volumn 330, Issue 6003, 2010, Pages 463-468

  Colaprete, Anthony ^a   Schultz, Peter ^b   Heldmann, Jennifer ^a   Wooden, Diane ^a   Shirley, Mark ^a   Ennico, Kimberly ^a   Hermalyn, Brendan ^b   Marshall, William ^a,h   Ricco, Antonio ^a   Elphic, Richard C ^a   Goldstein, David ^c   Summy, Dustin ^c   Bart, Gwendolyn D ^d   Asphaug, Erik ^e   Korycansky, Don ^e   Landis, David ^f   Sollitt, Luke ^g  

^a NASA AMES RESEARCH CENTER   (United States)

^b BROWN UNIVERSITY   (United States)

^c UNIVERSITY OF TEXAS AT AUSTIN   (United States)

^d UNIVERSITY OF IDAHO   (United States)

^e UNIVERSITY OF CALIFORNIA   (United States)

^f Aurora Design and Technology   (United States)

^g THE CITADEL   (United States)

^h UNIVERSITIES SPACE RESEARCH ASSOCIATION   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON DIOXIDE; HYDROCARBON; HYDROXYL RADICAL; ICE; SULFUR; VOLATILE ORGANIC COMPOUND; WATER;

ABSORBANCE; CARBON DIOXIDE; CHEMICAL COMPOSITION; CRATER; DETECTION METHOD; DUST; HYDROCARBON; HYDROXYL RADICAL; ICE; LUNAR CRUST; RADIOMETER; REGOLITH; REMOTE SENSING; SATELLITE MISSION; SPACECRAFT; SPECTROMETER; VOLATILE SUBSTANCE; WATER VAPOR;

ARTICLE; CAMERA; CONCENTRATION (PARAMETERS); FIELD EMISSION; LUNAR CRATER OBSERVATION AND SENSING SATELLITE; MOON; NEAR INFRARED SPECTROSCOPY; PRIORITY JOURNAL; RADIATION DETECTOR; SPACE FLIGHT; SPECTROMETRY; SUNLIGHT; TELECOMMUNICATION; ULTRAVIOLET RADIATION; WATER VAPOR; MICROCLIMATE;

EXTRATERRESTRIAL ENVIRONMENT; ICE; MOON; SPECTROSCOPY, NEAR-INFRARED; WATER;

EID: 77958160214     PISSN: 00368075     EISSN: 10959203     Source Type: Journal    
DOI: 10.1126/science.1186986     Document Type: Article

References (39)

1. A. Colaprete et al., Abstract 1861, 40th Lunar and Planetary Science Conference (Lunar and Planetary Science XL, Houston, TX, 2009).
2. W. C. Feldman et al., Science 281, 1496 (1998).
3. C. M. Pieters et al., Science 326, 568 (2009).
4. R. N. Clark, Science 326, 562 (2009).
5. J. M. Sunshine et al., Science 326, 565 (2009).
6. K. Watson, B. C. Murray, H. Brown, J. Geophys. Res. 66, 3033 (1961).
7. J. R. Arnold, J. Geophys. Res. 84 (B10), 5659 (1979).
8. R. R. Hodges Jr., Lunar Planet. Sci. 12, 451 (1981).
9. R. C. Elphic, V. R. Eke, L. F. A. Teodoro, D. J. Lawrence, D. B. J. Bussey, Geophys. Res. Let. 13, L13204 (2007).
10. D. H. Crider, R. R. Vondrak, J. Geophys. Res. 105 (E11), 26,773 (2003).
11. P. D. Spudis et al., Sol. Syst. Res. 32, 17 (1998).
12. 2O on the Centaur at the time of impact were <0.5, <1.25, and <1.5 kg, respectively. See SOM for additional description of in-flight measurement contamination control activities.
13. K. Ennico et al., Abstract 1878, 40th Lunar and Planetary Science Conference (Lunar and Planetary Science XL, Houston, TX, 2009).
14. The instrument suite included two down (nadir) viewing spectrometers both with a coaligned 1° FOV. The nadir NIR spectrometer measured wavelengths between 1.25 and 2.35 mm with a resolving power between 35 and 70. The UV/Vis spectrometer measured wavelengths between 0.26 and 0.65 μm, with a resolving power between 300 and 850. Additional information is provided in the SOM.
15. H. Noda et al., Geophys. Res. Lett. 35, L24203 (2008).
16. T. P. McClanahan et al., Abstract 2092, 40th Lunar and Planetary Science Conference (Lunar and Planetary Science XL, Houston, TX, 2009).
17. L. F. A. Teodoro et al., abstr. 1515, Annual Meeting of the Lunar Exploration Analysis Group (Houston, TX, 2009).
18. I. G. Mitrofanov et al., Science 330, 483 (2010).
19. D. A. Paige et al., Science 330, 479 (2010).
20. P. H. Schultz et al., Science 330, 468 (2010).
21. P. H. Schultz et al., Icarus 190, 295 (2007).
22. The observations spacecraft, the SSc, was three-axis stabilized and pointed to the impact target to within ±0.1 deg.
23. P. O. Hayne et al., Science 330, 477 (2010).
24. 2(9 parameters)/n (25). An error of ±25% in the scaler of the molecular absorbance corresponds to better than 99% confidence or better than 3 SD. The fractional error in the corresponding water vapor column density is then the root mean square of the independent point error in the linear mixing model (±5% at 1 SD) and the uncertainty in the radiance measurement at the 1.87-μm band center (∼28% in the spectrum in Fig. 3C). Thus, the water vapor mass is uncertain to ±28% (1 SD).
25. W. H. Press et al., Numerical Recipes (Cambridge Univ. Press, New York, 2007), chap. 15.
26. R. N. Clark, T. V. V. King, M. Klejwa, G. A. Swayze, N. Vergo, J. Geophys. Res. 95 (B8), 12653 (1990).
27. -3 was assumed when calculating the total cloud mass. The NIR water ice column optical depth was modeled in the same way. The 1.5-μm feature could be modeled to within about 14% (root mean square of 11% from fitting uncertainty and 9% from radiance measurement uncertainty). Using a 2.5-μm particle, consistent with observed UV/Vis-to-NIR radiance ratio, the UV/Vis continuum was fit with an uncertainty in the optical depth of ∼25% (5% from fitting uncertainty and 24% in radiance measurement uncertainty).
28. The water ice grain radius is estimated based on the band position in the spectrum shown in Fig. 3B. Submicron ice grains will have a band center less than 1.48 μm, and for a 15+ μm grain radius the band center is ∼1.54 μm (29). The 1.5-μm band center is at ∼1.51 μm, which is consistent with an ice grain ∼2 μm.
29. J. E. Hansen, J. B. Pollack, J. Atmos. Sci. 27, 265 (1970).
30. P. Rousselot et al., Asteorids, Comets, Meteors (Lunar and Planetary Institute, Houston, TX, 1991).
31. G. R. Gladstone et al., Science 330, 472 (2010).
32. D. Summy et al., abstr. 2267, 40th Lunar and Planetary Science Conference, (Lunar and Planetary Science XL, Houston, TX, 2009).
33. -4 photons/s was used in the OH number estimate.
34. The uncertainty in the water vapor mass derived from the OH prompt emission at ∼180 s after impact is based on the total uncertainty in the measured OH radiance at that time. The total uncertainty in OH radiance is based on the calibration error (<10%), instrument noise (from dark measurements at specific integration time), and uncertainty in the g factor (about 20%).
35. At 8 s after impact, the diameter of the ejecta cloud in the visible camera was ∼4.5 km, and the FOVs of the NIR and UV/Vis spectrometers were ∼10 km in diameter. At 20 s, the ejecta cloud diameter was ∼8.5 km and the FOVs of the spectrometers were approximately 9.6 km in diameter.
36. The total error is the propagated error for the masses of water vapor plus water ice divided by the dust mass, using the errors (1 SD uncertainties, quoted in Table 1) in the derived masses of each component.
37. D. Bockele'e-Morvan et al., in Comets II (University of Arizona Press, Tucson, AZ, 2004), pp. 391-423.
38. D. H. Wooden et al., in Comets II (University of Arizona Press, Tucson, AZ, 2004), pp. 33-66.
39. We thank the LCROSS Project and NASA's Exploration Systems Mission Directorate (ESMD) and NASA Science Mission Directorate (SMD) for support, and are very grateful to the LRO project and the LRO instrument leads for supporting the LCROSS targeting and impact observations, and for the three referees who provided reviews that greatly improved this paper. R.C.E. was supported by an LRO Participating Scientist grant.