{"id":14411,"date":"2017-08-15T21:36:48","date_gmt":"2017-08-15T13:36:48","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/nasa-counts-down-final-month-of-cassinis-tour-of-saturn\/"},"modified":"2017-08-15T21:36:48","modified_gmt":"2017-08-15T13:36:48","slug":"nasa-counts-down-final-month-of-cassinis-tour-of-saturn","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/nasa-counts-down-final-month-of-cassinis-tour-of-saturn\/","title":{"rendered":"NASA counts down final month of Cassini\u2019s tour of Saturn"},"content":{"rendered":"
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Artist\u2019s concept of the Cassini spacecraft during one the mission\u2019s five dives into the uppermost layers of Saturn\u2019s atmosphere before the mission ends Sept. 15. Credit: NASA\/JPL-Caltech<\/figcaption><\/figure>\n

NASA\u2019s Cassini orbiter sailed through the tenuous outermost reaches of Saturn\u2019s atmosphere without trouble Monday, performing the first of five close swings nearer to the planet than any previous spacecraft before a final dive Sept. 15 to end the probe\u2019s nearly 20-year mission.<\/p>\n

The plutonium-powered spacecraft made its closest brush to Saturn yet, close enough to require the activation of its chemical rocket thrusters to keep it stable.<\/p>\n

Cassini typically uses spinning gyro-like wheels buried inside the spacecraft to control its orientation with momentum shifts, but engineers were not sure the wheels were strong enough to counteract aerodynamic forces as the orbiter plowed through Saturn\u2019s outer atmosphere.<\/p>\n

The spacecraft came closest to Saturn at around 0422 GMT (12:22 a.m. EDT) Monday, and Cassini transmitted a radio signal nearly 24 hours later confirming it survived the flyby. NASA announced Tuesday that the first of five such dips into Saturn\u2019s atmosphere was successful.<\/p>\n

Cassini had used its rocket thrusters during many of the craft\u2019s flybys of Saturn\u2019s largest moon Titan, which has its own dense atmosphere.<\/p>\n

\u201cCassini\u2019s Titan flybys prepared us for these rapid passes through Saturn\u2019s upper atmosphere,\u201d said Earl Maize, Cassini project manager at NASA\u2019s Jet Propulsion Laboratory in Pasadena, California, before Monday\u2019s flyby. \u201cThanks to our past experience, the team is confident that we understand how the spacecraft will behave at the atmospheric densities our models predict.\u201d<\/p>\n

The spacecraft will soar less than 1,100 miles (1,770 kilometers) above Saturn\u2019s cloud tops on each of its last five orbits, then spiral out beyond the rings to make successive egg-shaped loops around the planet.<\/p>\n

Made mostly of hydrogen and helium, Saturn\u2019s atmosphere of golden haze sits above dense inner core scientists believe is made of rock and ice. One of the prime goals of Cassini\u2019s final months is to make measurements of Saturn\u2019s gravity and magnetic fields, data that could render an estimate of the core\u2019s size.<\/p>\n

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Cassini\u2019s on-board camera took this image of Saturn on Aug. 12. Credit: NASA\/JPL-Caltech\/Space Science Institute<\/figcaption><\/figure>\n

Depending on the density of Saturn\u2019s atmosphere at Cassini\u2019s flyby altitude, ground controllers could command the probe to conduct \u201cpop-up\u201d or \u201cpop-down\u201d maneuvers to fly farther or closer to the planet on the next four dives.<\/p>\n

Cassini\u2019s final close-up encounter with Titan on April 22 rerouted the spacecraft\u2019s orbit to pass between Saturn and its innermost ring, kicking off the mission\u2019s \u201cgrand finale\u201d with 22 week-long circuits of the solar system\u2019s second-biggest planet.<\/p>\n

Cassini\u2019s instruments were programmed to directly measure particles of Saturn\u2019s atmosphere during Monday\u2019s flyby.<\/p>\n

\u201cAs it makes these five dips into Saturn, followed by its final plunge, Cassini will become the first Saturn atmospheric probe,\u201d said Linda Spilker, Cassini project scientist at JPL. \u201cIt\u2019s long been a goal in planetary exploration to send a dedicated probe into the atmosphere of Saturn, and we\u2019re laying the groundwork for future exploration with this first foray.\u201d<\/p>\n

Scientists have concepts for a future dedicated probe to descend into Saturn\u2019s atmosphere to measure winds, density, and composition deep below the planet\u2019s cloud tops. Cassini will give researchers a taste.<\/p>\n

Cassini\u2019s radar was expected to conduct sounding measurements to reveal the large-scale structure of Saturn\u2019s atmosphere in a region hidden from the view of conventional cameras.<\/p>\n

\u201cIts radar will peer deep into the atmosphere to reveal small-scale features as fine as 16 miles (25 kilometers) wide \u2014 nearly 100 times smaller than the spacecraft could observe prior to the grand finale,\u201d NASA said in a press release.<\/p>\n

The final phase of Cassini\u2019s mission has already produced one surprising discovery. The space between Saturn and its rings is emptier than scientists expected, with Cassini detecting fewer impacts of tiny dust particles than predicted.<\/p>\n

Cassini conducted its final orbit adjustment with its on-board thrusters July 15, and the spacecraft is now on a collision course with Saturn.<\/p>\n

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NASA\u2019s Cassini spacecraft looks toward the night side of Saturn\u2019s moon Titan in a view that highlights the extended, hazy nature of the moon\u2019s atmosphere. During its long mission at Saturn, Cassini has frequently observed Titan at viewing angles like this, where the atmosphere is backlit by the Sun, in order to make visible the structure of the hazes. Cassini took this image May 29 with its narrow-angle camera. Credit: NASA\/JPL-Caltech\/Space Science Institute<\/figcaption><\/figure>\n

A long-distance flyby of Titan on Sept. 11 will naturally nudge Cassini on a trajectory to fall into Saturn. The spacecraft will be crushed by Saturn\u2019s atmosphere and will burn up, with the final radio signal from Cassini expected to arrive on Earth around 8 a.m. EDT (1200 GMT; 5 a.m. PDT) on Sept. 15.<\/p>\n

Running low on fuel, Cassini has explored Saturn and its moons for more than 13 years. The robotic explorer launched Oct. 15, 1997, from Cape Canaveral on top of a Titan 4 rocket, and entered orbit around Saturn on June 30, 2004, after a 2.2 billion-mile (3.5 billion-kilometer) interplanetary journey.<\/p>\n

Cassini deployed the European Space Agency\u2019s Huygens lander for a descent to the surface of Titan in 2005.<\/p>\n

Since its arrival, Cassini has circled Saturn almost 300 times, collected detailed imagery of Saturn\u2019s atmosphere and mysterious hexagonal polar vortex, explored its rings in minute detail, and observed 49 of Saturn\u2019s 62 known moons with close and long-range flybys.<\/p>\n

Originally designed for a four-year tour of Saturn, the nearly $3.3 billion mission has far outlived its original lifetime, producing stunning imagery of the planet and documenting seasonal changes as the gaseous world completed almost half of one 29-year orbit around the sun.<\/p>\n

Email the author.<\/i><\/b><\/p>\n

Follow Stephen Clark on Twitter: @StephenClark1.<\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Artist\u2019s concept of the Cassini spacecraft during one the mission\u2019s five dives into the uppermost layers of Saturn\u2019s atmosphere before the mission ends Sept. 15. Credit: NASA\/JPL-Caltech NASA\u2019s Cassini orbiter sailed through the tenuous outermost reaches of Saturn\u2019s atmosphere without trouble Monday, performing the first of five close swings nearer to the planet than any […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[2394,1183,1561,1562,2396],"class_list":["post-14411","post","type-post","status-publish","format-standard","hentry","category-news","tag-cassini","tag-jet-propulsion-laboratory","tag-planetary-science","tag-saturn","tag-titan"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14411"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=14411"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/14411\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=14411"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=14411"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=14411"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}