NASA's Juno spacecraft is on its way to Jupiter after being launched aboard an Atlas V rocket from the Cape Canaveral Air Force Station, Florida on August 5 at 11:25 a.m. Eastern. The solar-powered spacecraft will arrive at Jupiter in July 2016 and orbit its poles 33 times to find out more about the gas giant's interior, atmosphere and aurora. Scientists believe Jupiter holds the key to better understanding the origins of our solar system.
Scientists from NASA’s Juno mission to Jupiter discussed their first in-depth science results in a media teleconference on May 25, 2017, at 2 p.m. ET (11 a.m. PT, 1800 UTC), when multiple papers with early findings were published online by the journal Science and Geophysical Research Letters. Credit: NASA Jet Propulsion Laboratory
Like NASA’s earlier Pioneer spacecraft, Juno’s spinning makes its pointing very stable and easy to control. Just after launch, and before its solar arrays are deployed, Juno is being spun-up by rocket motors on its still attached second-stage rocket booster. Juno’s planned spin rate varies during the mission, as 1 RPM for cruise, 26e7783 RPM for science operations and 5 RPM for main engine maneuvers.
To simplify and decrease weight, all instruments are fixed. Then, in orbit at Jupiter, the spinning spacecraft sweep the fields of view of its instruments through space once for each rotation. At two rotations per minute, the instruments’ fields of view sweep across Jupiter about 400 times in the two hours it takes Juno to fly from pole to pole.
Juno’s trajectory to Jupiter consists of five phases over five years and one-and-a-half loops of the sun.
There are four cruise phases: Inner Cruise 1 (61 days), Inner Cruise 2 (598 days), Inner Cruise 3 (161 days), and Quiet Cruise (791 days).
An Earth flyby of 26 months after the launch had provided a boost to the spacecraft’s velocity, placing it on a trajectory for Jupiter. The transit time to Jupiter following this flyby was about three years, including the period of the initial capture orbit. The 30-minute orbit insertion burn had placed Juno in orbit around Jupiter in early July 2016.
Following the launch on August 5, 2011, Juno has used its main rocket motor twice, on Aug. 30 and Sept. 3, 2012, to modify its trajectory towards Jupiter. During cruise phases, 13 trajectory correction maneuvers to refine its orbital path have been done.
. Earth gravity assist flyby: October 9, 2013
. Distance Juno travels from launch to Earth gravity assist: 1,600 million kilometers (km)
. Juno’s altitude over Earth’s surface at closest point during gravity assist: 500 km (ISS is at approx. 400 km)
. Jupiter arrival: July 4, 2016, 7:29 p.m. (PDT)
. Distance of Jupiter to Earth at time of Jupiter orbit insertion: 869 million km
.One-way speed-of-light time from Jupiter to Earth in July 2016: 48 minutes, 19 seconds
Total distance traveled, launch to Jupiter orbit insertion: 2,800 million km
The Fantastic Voyage of JUNO to JUPITER (Full Story)
The U.S. orbiter JUNO was launched on August 5, 2011, in the direction of Jupiter. The main goals are to Reveal the story of the formation and evolution of Jupiter. Howdid Jupiter form? Does it have a solid core? How is its vast magnetic field generated?
Pluto's spacecraft few seconds after launch in August 2011. Credit: NASA/JPL
Then, the primary goal of this mission is to reveal the story of its formation and evolution. To do it, JUNO will be placed in an elliptical polar orbit. There, it will be able to observe Jupiter's gravity and magnetic fields, atmospheric dynamics and composition. Also, to see what that determines its properties and drives its evolution, it will study the interactions between the interior, the atmosphere and the magnetosphere.
On the top of Juno, is placed the Gravity Science experiment which measure the Jupiter's gravitational field and reveal its internal structure. In it, two transponders operate on frequencies Ka- and X-band to detect signals sent from NASA's Deep Space Network on Earth, which send immediately signals in return.
Example of that is, if a small change in frequencies is receive on Earth, that give a measure of how much Juno’s velocity has been modified by local variations of the Jupiter’s gravity. And, by the fact, that provide insight into the gas giant’s internal structure.
On the Spacecraft, MAG sensors are mounted on the boom at the end of one of Juno's three solar arrays - as far away from the spacecraft body as possible. Why? Simply to avoid confusion about the spacecraft magnetic field and the Jupiter's one.
In using the Advanced Stellar Compass images, the Juno's Magnetometer (MAG) can measure precisely the strength and the direction of Jupiter’s magnetic field and creates a detailed three-dimensional map of this one.
The Juno's Microwave Radiometer (MWR) probe provides data on the structure, the movement and the chemical composition to a depth as 1,000 atmospheres - about 342 miles below the visible cloud.
On the MWR, are placed six radiometers made to measure the microwaves coming from six cloud levels. Connected by a cable to a receiver sits in the instrument vault on the top of Juno, each antenna is extending from its hexagonal body.
Because many energetic particles through stream space interact with Jupiter’s magnetic field, Juno can measure these particles and studying their interaction o with. To do that, it uses the Jupiter Energetic Particle Detector or JEDI.
JEDI have three identical sensor unit, which each one have 6 ions and 6 electron views. Working in coordination with JADE and Waves instruments, it put a particular focus on the Jupiter's intense and impressive northern and southern auroras lights.
When you work with others, sometime you do great thing, big thing. That the case of the Jovian auroras Distributions Experiment or JADE who work with some other instruments to identify particles and processes that produce Jupiter's stunning auroras.
JADE includes an electronics box shared by four sensors: three detect electrons surrounding Juno and, the fourth, identify positively charged hydrogen, helium, oxygen and sulfur ions. So, when it flies over auroras, JADE characterize particles that are coming down Jupiter's magnetic field lines and crashing into its atmosphere.
The Waves instrument measure radio and plasma waves in Jupiter's magnetosphere, that is useful to understand the interactions between magnetic field, atmosphere and magnetosphere.
Consisting of a V-shaped antenna of four meters from tip to tip, similar to the rabbit-ear, one can detects the electric component of radio and plasma waves, and the other is sensitive to the magnetic component.
The magnetic antenna consists of a coil of fine wire wrapped 10,000 times around a 5.9-inch long core.
The search coil measures magnetic fluctuations in the audio frequency range.
Another team worker is the Ultraviolet Imaging Spectrograph or UVIS who take pictures of auroras in ultraviolet light. Whit JADE and JEDI instruments, UVIS can explain the relationship between auroras, streaming particles that create them, and the magnetosphere, as a whole.
UVIS has two separate sections: a dedicated telescope/spectrograph assembly and, located in Juno’s radiation-shielded, a vault electronics box.
To protect sensitive spacecraft electronics against heavy radiation environment and helping him for enabling sustained exploration, Juno carry the first-of-its-kind radiation shielded Electronics vault. Each of the titanium cube’s of eight sides measures nearly a square meter in area, about a third of an inch in thickness, and 18 kilograms in mass. This titanium box encloses Juno’s command and data handling box (brain), power and data distribution unit (heart) and about 20 other electronic assemblies. The whole vault weighs about 200 kilograms.
If you want to know the interactions between auroras, magnetic field and magnetosphere, you need to use the Jovian Infrared Auroras Mapper or JIRAM, which study Jupiter's atmosphere in and around the auroras. How? By probing atmosphere down to 30 to 45 miles below cloud tops, where the pressure is five to seven times greater than on Earth at sea level!
By its JIRAM’s camera and spectrometer, which splits light into its component wavelengths, like a prism, it takes pictures in infrared light, which is heat radiation, with wavelengths of two to five microns (millionths of a meter) - three to seven times longer than visible wavelengths.
To motivate public interest about Juno’s mission at Jupiter, NASA use JunoCam to capture color pictures of its cloud tops in visible light. People choose which one it want, that is engage it in History.
This camera head has a lens with a 58-degree cross-scan field of view. It acquires images by sweeping out that field who the spacecraft spins to cover an along-scan field of view of 360 degrees. Lines containing dark sky are subsequently compressed to an insignificant data volume. It takes images mainly when Juno is very close to Jupiter, with a maximum resolution of up to 1 to 2 miles per pixel.
CHARACTERISTIC OF JUNO’S SPACECRAFT
At the launch, Juno was pounded at 3,625 kilograms (kg), consisting of 1,593 kg of spacecraft, 1,280 kg of fuel and 752 kg of oxidizer.
At the dimensions of 3.5 meters (m) high by 3.5 m in diameter for Juno, we have three solar arrays of length of 9 m by 8.7 m for each one with a total surface area of more than 60 m squared.
These three solar panels extend outward from Juno’s hexagonal body, giving the overall spacecraft a span of more than 20 meters. From launch through end of mission, except few minutes during the Earth flyby, the solar panels will remain in sunlight continuously.
This is critical for the system because Jupiter’s orbit is five times farther from the sun and, so, the giant planet receives 25 times less sunlight than Earth’s.
Big challenge! Sure, because Juno is the first solar-powered spacecraft to operate at such a great distance from the sun. No problem for the mission because the power is well distributed.
In fact, Juno’s Electrical Power Subsystem manages the spacecraft power bus and distribution of power to payload, propulsion, heaters and avionics.
The power distribution and drive unit, monitors and manages the power bus, the available solar array power and battery state of charge, and control power distribution.
To generate the Power, the three solar arrays have 11 solar panels and one MAG boom. But, when Juno is off-sun or in eclipse and are tolerant of the Jupiter radiation environment, two 55 amp-hour lithium-ion batteries makes the job and provide the power.
During science orbits, the power modes are sized for either data collection during an orbit emphasizing microwave radiometry or gravity science.
The gravity science and telecom subsystem provides X-band command uplink and engineering telemetry and science data downlink for the entire post-launch, cruise and Jupiter orbital operations. The subsystem also provides for dual-band (X- and Ka-band) Doppler tracking for gravity science at Jupiter.
NASA’S NEW FRONTIERS PROGRAM
The Juno mission is the second spacecraft designed under NASA’s New Frontiers Program. The first was the Pluto New Horizons mission, launched in January 2006 and scheduled to reach Pluto’s moon Charon in 2015. The third mission will be OSIRIS-Rex, the first U.S. mission to carry materials from an asteroid back to Earth. The program provides opportunities to carry out medium-class missions identified as top priority objectives in the Decadal Solar System Exploration Survey, conducted by the Space Studies Board of the National Research Council in Washington.
. The Juno spacecraft was scheduled to reach Jupiter in July 2016, and the job is done.
. End of mission (deorbit): October 16, 2017
. Distance traveled in orbit around Jupiter: 560 million km
. Total distance, launch through Jupiter impact: 3,390 million km
. 1 Feb 2018: End of Jupiter Mission