{"id":15161,"date":"2016-10-16T01:23:45","date_gmt":"2016-10-15T17:23:45","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/mission-managers-keeping-juno-in-elongated-orbit-until-december\/"},"modified":"2016-10-16T01:23:45","modified_gmt":"2016-10-15T17:23:45","slug":"mission-managers-keeping-juno-in-elongated-orbit-until-december","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/mission-managers-keeping-juno-in-elongated-orbit-until-december\/","title":{"rendered":"Mission managers keeping Juno in elongated orbit until December"},"content":{"rendered":"
\"Artist's
Artist\u2019s concept of the solar-powered Juno spacecraft at Jupiter. Credit: NASA\/JPL-Caltech<\/figcaption><\/figure>\n

Ground teams are buying more time to study two sluggish valves inside the Juno spacecraft\u2019s fuel pressurization system and postponing a major engine burn that was scheduled for next week to reshape the probe\u2019s orbit around Jupiter, officials said Friday.<\/p>\n

The rocket burn was slated for Oct. 19 as the Juno spacecraft dived toward Jupiter for its second close approach, or perijove, since arriving in Jupiter\u2019s orbit July 4. The maneuver is necessary to place Juno into its final science orbit, an orbit selected to maximize the $1 billion mission\u2019s scientific bounty and minimize exposure to harmful radiation that could fry the craft\u2019s electronics.<\/p>\n

But ground controllers encountered an issue with two helium check valves inside Juno\u2019s fuel pressurization system Thursday, according to a NASA statement.<\/p>\n

\u201cTelemetry indicates that two helium check valves that play an important role in the firing of the spacecraft\u2019s main engine did not operate as expected during a command sequence that was initiated yesterday,\u201d said Rick Nybakken, Juno project manager at NASA\u2019s Jet Propulsion Laboratory in Pasadena, California. \u201cThe valves should have opened in a few seconds, but it took several minutes. We need to better understand this issue before moving forward with a burn of the main engine.\u201d<\/p>\n

After consulting with NASA Headquarters and Lockheed Martin, the manufacturer of the Juno spacecraft, the Juno team elected to delay the rocket firing, known as the period reduction maneuver, by at least one orbit to allow engineers to evaluate the valves, the space agency said in a press release issued late Friday.<\/p>\n

The period reduction maneuver is planned to be final burn of Juno\u2019s Leros 1b main engine, which successfully fired July 4 for 35 minutes to steer Juno into an initial orbit around Jupiter. Maneuvers needed later in Juno\u2019s mission \u2014 due to end in February 2018 \u2014 can be done using the orbiter\u2019s smaller rocket thrusters.<\/p>\n

The Leros 1b engine burns a mixture of hydrazine and nitrogen tetroxide to produce about 145 pounds of thrust. Juno carries a supply of gaseous helium to pressurize the propellant tanks and plumbing before an engine burn.<\/p>\n

Juno slid into a looping orbit around Jupiter after the make-or-break July 4 arrival burn. In its current orbit, which takes the spacecraft as far as 5 million miles (8.1 million kilometers) from Jupiter, Juno completes one lap around the giant planet every 53 days.<\/p>\n

\"The
The Juno spacecraft was supposed to complete two 53-day orbits around Jupiter, then lower its orbit Oct. 19 to fly around the planet once every 14 days. That engine burn has been rescheduled for no earlier than Dec. 11. Credit: NASA\/JPL Caltech<\/figcaption><\/figure>\n

The period reduction maneuver is designed to do exactly what its name implies: reduce the period of time for Juno to make one orbit from 53 days to 14 days.<\/p>\n

The rocket burn will slow down Juno\u2019s speed around Jupiter, dropping the highest point of each orbit closer to the planet. The laws of orbital mechanics require the burn to happen when Juno is close to the planet, at perijove just a few thousand miles above Jupiter\u2019s cloud tops.<\/p>\n

The next time Juno will be that close after next week is Dec. 11, so managers have penciled in that date for the period reduction maneuver.<\/p>\n

Scientists say Juno can still collect the same type of science data as expected regardless of whether its orbit is lowered or not, but the longer path around Jupiter means fewer opportunities to capture the measurements and imagery researchers are eager to see.<\/p>\n

Ground controllers planned to switch off most of Juno\u2019s science instruments for the Oct. 19 flyby to allow the spacecraft to focus on the engine burn. With the change of plans, all nine of Juno\u2019s instruments, comprising 29 individual sensors, will be activated for the close approach next week.<\/p>\n

\u201cIt is important to note that the orbital period does not affect the quality of the science that takes place during one of Juno\u2019s close flybys of Jupiter,\u201d said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. \u201cThe mission is very flexible that way. The data we collected during our first flyby on Aug. 27 was a revelation, and I fully anticipate a similar result from Juno\u2019s Oct. 19 flyby.\u201d<\/p>\n

Juno\u2019s objective is to unravel the mysteries of Jupiter\u2019s interior, learn how the planet\u2019s intense magnetic field is generated and how it traps charged particles in toxic radiation belts, and probe the structure beneath Jupiter\u2019s turbulent clouds to find out what drives the gaseous world\u2019s storms and whether it has a solid core.<\/p>\n

Mission planners originally intended to put Juno into a preliminary 107-day orbit around Jupiter after arrival, then drive the probe into the shorter 14-day orbit Oct. 19. But officials decided after Juno\u2019s launch in August 2011 to change the plan, and instead have Juno go into a 53-day orbit, where it would fly around the planet two times before starting the mission\u2019s regular science campaign.<\/p>\n

Managers had contingency plans to hold off on the period reduction maneuver in case Juno encountered technical problems, such as the current issue with the propulsion system, or if there was more radiation in the spacecraft\u2019s path than anticipated.<\/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 solar-powered Juno spacecraft at Jupiter. Credit: NASA\/JPL-Caltech Ground teams are buying more time to study two sluggish valves inside the Juno spacecraft\u2019s fuel pressurization system and postponing a major engine burn that was scheduled for next week to reshape the probe\u2019s orbit around Jupiter, officials said Friday. The rocket burn was […]<\/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":[1183,1929,1606,472,2020,1561,3559,2612],"class_list":["post-15161","post","type-post","status-publish","format-standard","hentry","category-news","tag-jet-propulsion-laboratory","tag-juno","tag-jupiter","tag-lockheed-martin","tag-new-frontiers","tag-planetary-science","tag-scott-bolton","tag-swri"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15161"}],"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=15161"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15161\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=15161"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=15161"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=15161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}