{"id":15422,"date":"2016-06-23T22:23:12","date_gmt":"2016-06-23T14:23:12","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/juno-right-on-target-for-july-4-rendezvous-with-jupiter\/"},"modified":"2016-06-23T22:23:12","modified_gmt":"2016-06-23T14:23:12","slug":"juno-right-on-target-for-july-4-rendezvous-with-jupiter","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/juno-right-on-target-for-july-4-rendezvous-with-jupiter\/","title":{"rendered":"Juno right on target for July 4 rendezvous with Jupiter"},"content":{"rendered":"
\"Artist's
Artist\u2019s concept of the Juno spacecraft on approach to Jupiter. Credit: Lockheed Martin<\/figcaption><\/figure>\n

NASA\u2019s Juno spacecraft, running on solar power more than 500 million miles from the sun, is on final approach for a Fourth of July arrival at Jupiter for a year-and-a-half campaign of exploration.<\/p>\n

Engineers this week are preparing the probe for a make-or-break rocket burn late July 4 to swing into orbit around the solar system\u2019s largest planet and become the second craft to ever set up residency there.<\/p>\n

Juno will orbit Jupiter until February 2018, passing within 3,100 miles (5,000 kilometers) from Jupiter\u2019s turbulent cloud tops, nearly 10 times closer than planned for any previous flyby or orbiter mission.<\/p>\n

The goal of the $1.1 billion mission, which launched from Earth in August 2011, is to survey the deep interior of Jupiter, conduct measurements of its swirling atmosphere and robust magnetic field, and attempt to sort out how the giant world formed at the birth of the solar system.<\/p>\n

The July 4 main engine firing will take place with Juno on autopilot. It takes 48 minutes for a radio signal to travel one way from Earth to Jupiter, longer than the 35-minute duration of the orbit insertion burn itself.<\/p>\n

\u201cIt\u2019s a one-shot deal,\u201d said Scott Bolton, Juno\u2019s principal investigator from the Southwest Research Institute in San Antonio. \u201cThe whole thing is riding on this JOI \u2014 Jupiter Orbit Insertion \u2014 activity on July 4. Somebody asked, \u2018When does the nail biting start?\u2019 It\u2019s already started. We\u2019re getting close.<\/p>\n

\u201cI can\u2019t wait to get there,\u201d Bolton said. \u201cOne of the primary goals of Juno is to learn the recipe for solar systems. How do you make the solar system? How do you make the planets in the solar system, and, in fact, not just our solar system, but how do you make the planets we discover in other solar systems?\u201d<\/p>\n

With Juno\u2019s rendezvous, Jupiter will get its first long-term visitor since NASA\u2019s Galileo orbiter ended its mission in 2003.<\/p>\n

Interplanetary navigators at NASA\u2019s Jet Propulsion Laboratory in California have put Juno right on course for a cosmic bull\u2019s-eye, aiming for a narrow corridor over Jupiter\u2019s north pole to place the spacecraft in the right position for the arrival maneuver.<\/p>\n

Mission managers canceled a course-correction planned for May 31, and three follow-up burns scheduled this month are also unnecessary with Juno\u2019s perfect trajectory, according to Rick Nybakken, Juno\u2019s project manager at JPL.<\/p>\n

\u201cWe have the best interplanetary navigation people in the world here at JPL, and once again they nailed it,\u201d Nybakken told Spaceflight Now in an interview.<\/p>\n

\"Juno
Juno principal investigator Scott Bolton. Credit: NASA\/Aubrey Gemignani<\/figcaption><\/figure>\n

Juno\u2019s last course-correction was on Feb. 3, when the probe fired its thrusters to slightly nudge the spacecraft\u2019s flight path, changing its speed by just 0.7 mph, or 0.31 meters per second.<\/p>\n

It turns out that maneuver was good enough to carry Juno through its July 4 encounter with Jupiter. The spacecraft\u2019s optical navigation camera is tracking Jupiter, and the planet is right in Juno\u2019s crosshairs.<\/p>\n

\u201cWe\u2019ve been seeing Jupiter for several weeks now, so we don\u2019t expect any surprise getting closer,\u201d said Jeff Lewis, Juno\u2019s flight operations lead engineer at Lockheed Martin, which built the spacecraft and sends commands to the probe from a control center near Denver.<\/p>\n

As of Thursday, Juno was about 6 million miles (10 million kilometers) from Jupiter. It will close that distance over the next 11 days.<\/p>\n

A shield covering Juno\u2019s main engine opened Monday, the first of several key steps over the next couple of weeks to configure the propulsion system for the July 4 burn. Mission control also uplinked the command sequence for Juno\u2019s arrival, allowing the spacecraft to fly itself through the critical insertion burn, if necessary.<\/p>\n

But engineers plan to oversee several more days of preparatory activities before handing over control to Juno\u2019s on-board computer June 30.<\/p>\n

Next week, the ground team will prime Juno for the engine burn by warming up the craft\u2019s tank of gaseous helium used to pressurize propulsion system. Once that step is complete, Juno will pressurize its propellant system, which consists of a mix of hydrazine and nitrogen tetroxide, liquids at stable temperatures that can be stored for years in space.<\/p>\n

The final commands for the July 4 arrival will beamed up to Juno through NASA\u2019s Deep Space Network on June 30, Lewis said.<\/p>\n

\u201cIt will be completely hands-off from that point, (but) we\u2019ll be ready to do anything, if need be, from the ground,\u201d Lewis said in a recent interview with Spaceflight Now.<\/p>\n

All of Juno\u2019s science instruments will be turned off June 29 to focus all of the spacecraft\u2019s energy and computing power on the crucial insertion burn set to begin at 11:18 p.m. EDT July 4 (0318 GMT July 5).<\/p>\n

Juno will spin up to 5 rpm for the maneuver, point the engine toward the correct vector, and fire it for 35 minutes. Orbital dynamics experts want to change the spacecraft\u2019s velocity by 1,211 mph (541.7 meters per second), just the right speed adjustment, or delta-v, to put Juno in a wide, egg-shaped 53-day orbit around Jupiter.<\/p>\n

\"This
This diagram illustrates the size of the Juno spacecraft with its three huge solar array wings. The large panels are necessary to generate power at Jupiter\u2019s distance. Credit: NASA\/JPL-Caltech<\/figcaption><\/figure>\n

With its three solar array wings stretching as wide as a basketball court, Juno will reach record speeds as Jupiter\u2019s immense gravity pulls the spacecraft toward the gas giant. On July 4, Juno will top out at more than 150,000 mph (more than 250,000 kilometers per hour) relative to Earth, making it the fastest human-made object in history, according to NASA.<\/p>\n

Jupiter\u2019s gravity will tug the spacecraft over its north pole, then as close as 2,900 miles (4,667 kilometers) as Juno fires up its engine.<\/p>\n

\u201cThat\u2019s the key to the speed,\u201d Bolton said of Jupiter\u2019s gravity. \u201cWe humans can\u2019t build a rocket quite that fast. It\u2019s hard to do that, so we\u2019re getting the speed by Jupiter pulling us in. It\u2019s all part of celestial forces.\u201d<\/p>\n

During Juno\u2019s 35-minute burn, engineers and scientists across the solar system on Earth will monitor the maneuver\u2019s progress by listening for tones broadcast by the spacecraft\u2019s radio. Juno will send home tones at different frequencies as the probe achieves key steps during the insertion sequence.<\/p>\n

The direction required for the engine burn means Juno\u2019s high-gain antenna will be pointed away from Earth, so the probe can only send limited status updates with its low-data rate antenna.<\/p>\n

The July 4 insertion burn will mark the third time Juno has fired its main engine. Two big deep space maneuvers in 2012 went off without a hitch, setting up for a flyby of Earth in 2013 to slingshot Juno toward Jupiter. That gave officials confidence, but the maneuver at Jupiter will offer new challenges.<\/p>\n

\u201cWe know how to set up the propulsion system. We know how the engine performs,\u201d Nybakken said. \u201cThe only thing new here is how the main engine performs, and the spacecraft performs, in Jupiter\u2019s intense radiation environment.\u201d<\/p>\n

Engineers and software coders developed commands for Juno to quickly and automatically respond to any fault caused by radiation during the July 4 arrival burn. If radiation triggers a computer reset and interrupts the orbit insertion engine firing, Juno\u2019s software has an \u201cauto restart\u201d feature to resume the burn within a few minutes, Nybakken said.<\/p>\n

Juno will brush by Jupiter\u2019s extreme radiation belt during each of its planned 37 low passes over the planet during its mission, beginning July 4. The radiation dose will build on each orbit, subjecting Juno to greater doses of nasty computer-zapping high-energy electrons toward the end of its 20-month campaign.<\/p>\n

The orbiter will fire its main engine again around Oct. 19 to lower the high point, or apojove, of its path around Jupiter to cycle from a 53.5-day orbit to a 14-day orbit for regular science operations.<\/p>\n

The spacecraft\u2019s vital electronics are housed in an armored titanium box, or vault, to protect against radiation that could damage computers, sensors and other crucial components.<\/p>\n

\"An
An illustration of Jupiter\u2019s magnetosphere, radiation belts and aurorae. Credit: SWRI<\/figcaption><\/figure>\n

\u201cThere are two kinds of radiation,\u201d Bolton said. \u201cOne is called total dose where I\u2019m just adding it up and eventually something stops working. The other is the instantaneous flux, like a single event upset, so I have really high-speed electrons coming through and they just eat the electronics right then and there. That\u2019s still pretty harsh even in the beginning \u2014 the potential for that, at least \u2014 but we\u2019re going through even worse regions later.\u201d<\/p>\n

Without the titanium shield, Juno likely would not survive even one trip around Jupiter. Scientists predict Juno will be exposed to radiation equivalent to 100 million dental X-rays during the mission.<\/p>\n

\u201cOf course, we\u2019re going through that radiation as fast as we can, so we\u2019re hoping to not be exposed too long,\u201d Bolton said. \u201cAlmost any of it would kill any of us right away. Even if we were behind all the armor that Juno has, humans wouldn\u2019t do so well.\u201d<\/p>\n

Juno\u2019s first dip toward Jupiter is designed to avoid the worst the planet has to offer, but there are still unknowns.<\/p>\n

\u201cIt\u2019s a spacecraft, not a human, thank God, but it\u2019s still something,\u201d Nybakken told Spaceflight Now. \u201cObviously, radiation tolerance and the ability to operate in that environment has been a focus area for us from day one, so we\u2019ve been working on this for 10 years.\u201d<\/p>\n

Jupiter\u2019s magnetic field traps high-energy particles in belts like Earth\u2019s, but the scale of the gas giant makes it a \u201cplanet on steroids,\u201d Bolton said, accumulating hazards to a craft like Juno.<\/p>\n

\u201cWe\u2019ve armored it up because Jupiter is attacking us,\u201d Nybakken said. \u201cThose energetic particles, the electrons and the protons, are hitting us at the speed of light from all different angles, so it\u2019s a very intense environment. It\u2019s the most dangerous and hostile environment anywhere in the solar system outside of the sun, and we\u2019re going right into the heart of it.\u201d<\/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 Juno spacecraft on approach to Jupiter. Credit: Lockheed Martin NASA\u2019s Juno spacecraft, running on solar power more than 500 million miles from the sun, is on final approach for a Fourth of July arrival at Jupiter for a year-and-a-half campaign of exploration. Engineers this week are preparing the probe for a […]<\/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":[1183,1929,1606,472,1561,2612],"class_list":["post-15422","post","type-post","status-publish","format-standard","hentry","category-news","tag-jet-propulsion-laboratory","tag-juno","tag-jupiter","tag-lockheed-martin","tag-planetary-science","tag-swri"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15422"}],"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=15422"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/15422\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=15422"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=15422"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=15422"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}