View Full Version : Welcome to Jupiter – NASA’s Juno Achieves Orbit around ‘King of the Planets’

2016-Jul-05, 07:50 AM
Welcome to Jupiter! NASA’s Juno spacecraft (http://www.universetoday.com/129695/juno-snaps-final-view-of-jovian-system-ahead-of-independence-day-orbital-insertion-fireworks-tonight-watch-live/) is orbiting Jupiter (http://www.universetoday.com/129594/7-days-out-from-orbital-insertion-nasas-juno-images-jupiter-and-its-largest-moons/) at this moment!
“NASA has done it again!” pronounced an elated Scott Bolton, investigator of Juno from Southwest Research Institute in San Antonio, to loud cheers and applause from the overflow crowd of mission scientists and media gathered at the post orbit media briefing at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.
After a nearly five year journey covering 1.7-billion-miles (2.8-billion-kilometers) across our solar system, NASA’s basketball court-sized Juno orbiter achieved orbit around Jupiter, the ‘King of the Planets’ on Monday, July 4, in a gift to all Americans on our 240th Independence Day and a gift to science to elucidate our origins.
“We are in orbit and now the fun begins, the science,” said Bolton at the briefing. "We just did the hardest thing NASA's ever done! That's my claim. I am so proud of this team.”
Solar powered Juno successfully entered orbit around Jupiter after completing a must-do 35-minute-long firing of the main engine known as Jupiter Orbital Insertion or JOI.
“The mission team did great. The spacecraft did great. We are looking great. It’s a great day.”
Engineers tracking the telemetry received confirmation that the JOI burn was completed as planned at 8:53 p.m. PDT (11:53 p.m. EDT) Monday, July 4.
“Independence Day always is something to celebrate, but today we can add to America’s birthday another reason to cheer -- Juno is at Jupiter,” said NASA administrator Charlie Bolden.
“And what is more American than a NASA mission going boldly where no spacecraft has gone before? With Juno, we will investigate the unknowns of Jupiter’s massive radiation belts to delve deep into not only the planet’s interior, but into how Jupiter was born and how our entire solar system evolved.”
The do-or-die burn of Juno’s 645-Newton Leros-1b main engine started at 8:18 p.m. PDT (11:18 p.m. EDT), which had the effect of decreasing the spacecraft’s velocity by 1,212 miles per hour (542 meters per second) and allowing Juno to be captured in orbit around Jupiter. There were no second chances.
All of the science instruments were turned off on June 30 to keep the focus on the nail-biting insertion maneuver and preserve battery power, said Bolton.
“After a 1.7 billion mile journey we hit the burn target within one second,” Rick Nybakken, Juno project manager from JPL, reported at the briefing. “That’s how good our team is!”
To accomplish the burn, the spacecraft first had adjust it attitude to point the engine in the required direction to slow the spacecraft and the simultaneously also had the effect such that the life giving solar panels were pointing away from the sun. It the only time during the entire mission at Jupiter that the solar panels were in darkness and not producing energy.
The spacecraft’s rotation rate was also spun up from 2 to 5 revolutions per minute (RPM) to help stabilize it during JOI. Juno is spin stabilized to maintain pointing.
After the burn was complete, Juno was spun down and adjusted to point to the sun before it ran out of battery power.
We have to get the blood flowing through Juno’s veins, Bolton emphasized.
It is equipped with 18,698 individual solar cells over 60 square meters of surface on the solar arrays to provide energy. Juno is spinning like a windmill through space with its 3 giant solar arrays. It is about 540 million miles (869 million kilometers) from Earth.
Signals traveling at the speed of light take 48 minutes to reach Earth, said Nybakken.
So the main engine burn, which was fully automated, was already over for some 13 minutes before the first indications of the outcome reach Earth via a series of Doppler signals and tones.
“Tonight, 540 million miles away, Juno performed a precisely choreographed dance at blazing speeds with the largest, most intense planet in our solar system,” said Guy Beutelschies, director of Interplanetary Missions at Lockheed Martin Space Systems.
“Since launch, Juno has operated exceptionally well, and the flawless orbit insertion is a testament to everyone working on Juno and their focus on getting this amazing spacecraft to its destination. NASA now has a science laboratory orbiting Jupiter.”
“Juno is also the farthest mission to rely on solar power. And although they provide only 1/25th the power at Earth, they still provide over 500 watts of power at Jupiter,” said Nybakken.
Initially the spacecraft enters a long, looping polar orbit lasting about 53 days. That highly elliptical orbit will be trimmed to 14 days for the regular science orbits.
The orbits are designed to minimize contact with Jupiter’s extremely intense radiation belts. The nine science instruments are shielded inside a ½ thick vault built of Titanium to protect them from the utterly deadly radiation of some 20,000,000 rads.
During a 20 month long science mission - entailing 37 orbits lasting 14 days each – the probe will plunge to within about 3000 miles of the turbulent cloud tops and collect unprecedented new data that will unveil the hidden inner secrets of Jupiter’s origin and evolution.
But the length and number of the science orbits has changed since the mission was launched almost 5 years ago in 2011.
Originally Juno was planned to last about one year with an orbital profile involving 33 orbits of 11 days each.
Juno is the fastest spacecraft ever to arrive at Jupiter and was moving at over 165,000 mph relative to Earth and 130,000 mph relative to Jupiter at the moment of JOI.
Juno's principal goal is to understand the origin and evolution of Jupiter.
“With its suite of nine science instruments, Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras. The mission also will let us take a giant step forward in our understanding of how giant planets form and the role these titans played in putting together the rest of the solar system. As our primary example of a giant planet, Jupiter also can provide critical knowledge for understanding the planetary systems being discovered around other stars,” according to a NASA description.
The $1.1 Billion Juno was launched on Aug. 5, 2011 from Cape Canaveral, Florida atop the most powerful version of the Atlas V rocket augmented by 5 solid rocket boosters and built by United Launch Alliance (ULA). That same Atlas V 551 version just launched MUOS-5 for the US Navy on June 24.
The Juno spacecraft was built by prime contractor Lockheed Martin in Denver.
The last NASA spacecraft to orbit Jupiter was Galileo in 1995. It explored the Jovian system until 2003.
Stay tuned here for Ken's (http://www.universetoday.com/author/ken-kremer/) continuing Earth and Planetary science and human spaceflight news.
Ken Kremer
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2016-Jul-05, 08:36 AM
amazing achievement, well done Juno team.