{"id":899,"date":"2013-07-26T04:05:51","date_gmt":"2013-07-26T04:05:51","guid":{"rendered":"http:\/\/192.168.10.99\/KES\/?p=899"},"modified":"2016-10-04T18:05:59","modified_gmt":"2016-10-04T18:05:59","slug":"some-insights-into-charon-and-what-roles-laboratory-work-can-play-in-new-horizons-science","status":"publish","type":"post","link":"https:\/\/www.kandrsmith.org\/KES\/index.php\/2013\/07\/26\/some-insights-into-charon-and-what-roles-laboratory-work-can-play-in-new-horizons-science\/","title":{"rendered":"Some insights into Charon and what roles laboratory work can play in New Horizons science."},"content":{"rendered":"

Reposted from\u00a0https:\/\/blogs.nasa.gov\/mission-ames\/2013\/07\/26\/some-insights-into-charon-and-what-roles-laboratory-work-play-in-new-horizons-science\/<\/a>.<\/p>\n

These are talk summaries from the afternoon of July 24th at the Pluto Science Conference<\/a> being held this week, July 22-26, 2013 at the Johns Hopkins University Applied Physics Lab in Laurel, MD.<\/p>\n

Marc Buie (SwRI<\/b>) walked us through \u201cThe Surface of Charon.\u201d Charon was detected by Jim Christy in April 1978, in what were originally dubbed \u201cbad images\u201d from the Naval Observatory, but not confirmed as a satellite by the IAU until February 1985. Charon is about 1 arcsecond from and ~1.5x mag fainter than Pluto. An occultation measurement in April 1980 confirmed the detection.<\/p>\n

\u201cMutual Event Season\u201d<\/i> is when every half orbit of Charon passes in front or behind Pluto. This occurred over 1985-1990 time frame. For the specific orientation where \u201cCharon went behind Pluto,\u201d as observed from Earth, you can directly measure\u2019s Charon\u2019s albedo, the size ratio between Pluto and Charon and start deriving its composition. So, work in earnest to determine Charon\u2019s surface started in the mid-1980s.<\/p>\n

In 1987, Marc Buie and his colleagues got IR spectra using a single-channel detector and a circular variable filter, the best in spectrographs at the time, and this revealed Pluto\u2019s atmosphere is methane dominated and Charon\u2019s atmosphere is water dominated, and they do not<\/i> look like each other.<\/p>\n

Hubble Space Telescope (HST) entered the scene and a series of observations of Pluto and Charon with HST started in 1992. The first rotational light curve of Charon was obtained in 1992-1993, indicating a 8% variation in the brightness, much smaller than that for Pluto and the data also confirmed that Charon was tidally locked with Pluto (just like our Moon is tidally locked with Earth, showing the same face). Marc Buie and his colleagues obtained HST NICMOS near-infrared spectrum in 1998 of both Pluto & Charon.<\/p>\n

<\/a><\/p>\n

Comparison of Pluto and Charon infrared spectra, taken in 1998 at the same epoch (near in time with each other), with HST NICMOS (near infrared camera and spectrometer aboard Hubble).<\/p>\n

A mystery.<\/i> Spectra from Tethys, one of Saturn\u2019s moons, has a remarkable agreement with Charon\u2019s spectra, despite the bodies are of different temperatures and albedos? Will they have similar compositions when the New Horizons spacecraft flies by? The spectra is also not fit precisely with just water, so there is another unidentified species there.<\/p>\n

Marc Buie was observing Pluto & Charon just last night (July23rd<\/sup>, 2013) with the Adaptive Optics mode of the OSIRIS instrument on Keck. This instrument achieves comparable spatial resolution as Hubble. At the conference, he showed off the latest image, \u201chot off the press.\u201d<\/em><\/p>\n

Predictions for New Horizons<\/i>: Charon to have a heavily cratered surface with modest (subtle) albedo and color features. Expect to see differences between the Pluto and anti-Pluto hemispheres.<\/p>\n

Francesca DeMeo (MIT)<\/b> talk was entitled \u201cNear-Infrared Spectroscopic Measurements of Charon with the VLT.\u201d She began her talk stating that TNOs (Trans-Neptunian Objects) can be characterized\u00a0 as (1) volatile-rich (lots of N2<\/sub>, CO, CH4<\/sub>), (2) volatile-transition, (3) water+ammonia rich (H2<\/sub>O, NH3<\/sub>), and (4) volatile-poor (neutral to very red colors, maybe some water ice). No TNOs, to date, show evidence for CO2<\/sub>. Her analog is to Charon is Orcus, a TNO with its own moon Vanth. Both are water and ammonia-rich bodies.<\/p>\n

<\/a><\/p>\n

Comparison of two water and ammonia-rich bodies: the TNO Orcus and Pluto\u2019s moon Charon.<\/p>\n

She observed \u00a0Charon in 2005 using the VLT (8m telescope) with AO (adaptive optics), which separates Pluto. Her Pluto data is published in DeMeo et al 2010. Charon data was presented here in her talk and showed a comparison with Jason Cook\u2019s data from 2007 and F. Merlin\u2019s data from 2010, as they were looking at the same surface location. She is using the JPL Horizons longitude system.<\/p>\n

For a review of Trans Neptunian Objects, she recommends Mike Brown\u2019s 2012 Review Paper\u00a0http:\/\/adsabs.harvard.edu\/abs\/2012AREPS..40..467B<\/a>.<\/p>\n

Gal Sarid (Harvard)<\/b> followed with \u201cMasking Surface Water Ice Features on Small Distant Bodies.\u201d Minor (icy) bodies (TNOS, Centaurs, comets) are a diverse population with varied size, composition and structure. Their surface compositions show evidence for water ice and other volatile species. They are understood to be remnants of a larger population of planetesimals. He stepped us though his thermal and physical model of a radius=1200km object to reveal the possible insides of these minor icy bodies. Observationally this could be tested by inspecting impact crater that could eject subsurface material. From his computations he varies the ratio of carbon (dust) to water ice to give predictions for water band depth. When he compares the colors of the computed spectra they match very ice-rich TNO bodies, but his work reveals questions to explain the B-R colors. The models may need more other ices (methane, methanol).<\/p>\n

Reggie Hudson (NASA GSFC<\/b>), a laboratory spectroscopist, presented <\/b>\u00a0\u201cThree New Studies of the Spectra and Chemistry of Pluto Ices.\u201d At NASA Goddard, they have equipment to test ices with their vacuum-UV (vacuum-ultraviolet). \u00a0He showed 120-200 nm results of\u00a0N2<\/sub> +\u00a0CH4<\/sub> at 10 K. A second study was to measure\u00a0CH4<\/sub> ice in the infrared.\u00a0CH4<\/sub> has three phases: high temp crystalline T > 20.4 K, low temp crystalline T < 20.4 K, and amorphous\u00a0CH4<\/sub> forms around 10 K. He showed results for solid\u00a0CH4<\/sub> from 14-30 K over 2.17 to 2.56 microns and 7.58 to 7.81 microns. Their lab also has the ability to irradiate the samples, and when they have done so, certain phases recrystallize, but that is a function of temperature. Future work involves completing lab data of C2<\/sub>H2<\/sub>,\u00a0CH4<\/sub> and C2<\/sub>H6<\/sub>. Their lab website is\u00a0http:\/\/science.gsfc.nasa.gov\/691\/cosmicice\/<\/a>.<\/p>\n

Brant Jones (University of Hawaii) <\/b>discussed <\/b>\u00a0\u201cFormation of High Mass Hydrocarbons of Kuiper Belt Objects.\u201d \u00a0They irradiate their ices with a laser and their measurement technique is a \u201cReflectron time-of-flight mass spectrometer.\u201d They have identified 56 different hydrocarbons wit their highest mass C22<\/sub>Hm<\/sub> where 36 < m < 46. Future work is to investigate PAHs, look at \u201cprocessed ices\u201d and study different compositions, and study exact structures.<\/p>\n

Christopher Materese (NASA Ames<\/b>) spoke on \u201cRadiation Chemistry on Pluto: A Laboratory Approach.\u201d Reporting on their laboratory work at NASA Ames, in their setup, they radiate their ices with ultraviolet (UV). Now for Pluto, the atmosphere will be opaque (not-transparent) to UV radiation. Secondary electrons generated by ion processes, however, drive the chemistry and their energy (keV-MeV) is similar to that provided by UV radiation. He presented NIR (near infrared) and MIR (mid-infrared) spectra of his irradiated ices. They have completed over 20 molecular components. They also have a GC-MS (gas chromatograph\u2013mass spectrometer) to measure the masses of the molecules they create.<\/p>\n

The importance of laboratory work cannot be underestimated. It can help with predictions and equally important help with identification of molecules. Then once molecules and their abundances are determined, that can fold into more complicated models to look at volatile transport.<\/i><\/p>\n","protected":false},"excerpt":{"rendered":"

Reposted from\u00a0https:\/\/blogs.nasa.gov\/mission-ames\/2013\/07\/26\/some-insights-into-charon-and-what-roles-laboratory-work-play-in-new-horizons-science\/. These are talk summaries from the afternoon of July 24th at the Pluto Science Conference being held this week, July 22-26, 2013 at the Johns Hopkins University Applied Physics Lab in Laurel, MD. Marc Buie (SwRI) walked us through \u201cThe Surface of Charon.\u201d Charon was detected by Jim Christy in April 1978, in … Continue reading Some insights into Charon and what roles laboratory work can play in New Horizons science.<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[11],"tags":[42,44,9,8,51],"class_list":["post-899","post","type-post","status-publish","format-standard","hentry","category-science","tag-charon","tag-hst","tag-new-horizons","tag-pluto","tag-tnos"],"_links":{"self":[{"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/posts\/899","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/comments?post=899"}],"version-history":[{"count":0,"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/posts\/899\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/media?parent=899"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/categories?post=899"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kandrsmith.org\/KES\/index.php\/wp-json\/wp\/v2\/tags?post=899"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}