In the midst of Independence Day festivities, NASA's Juno orbiter celebrated its own American heritage with a daredevil maneuver. Mission scientists anxiously watched as the $1.1 billion spacecraft delicately edged itself into the gravitational embrace of Jupiter and successfully parked in orbit around this behemoth world, which is by far the largest planetary body in the solar system.
"This is the one time I don't mind being stuck in a windowless room on the night of the 4th of July," Scott Bolton, Juno's principal investigator, said in a NASA statement. "The mission team did great. The spacecraft did great. We are looking great. It's a great day."
After five years of spaceflight and over a decade of preparation, Juno has at last reached its target. It is only the second orbiter in history to visit Jupiter after the Galileo spacecraft, which studied the planet from 1995 to 2003.
For the next three months, the Juno team will be focused on calibrating the spacecraft's equipment, before conducting another orbital maneuver on October 19. This burn will send Juno into a highly elliptical polar orbit around Jupiter, and that's when the real mission science will begin.
Judging by its sophisticated onboard toolkit, it will be well worth the wait, because Juno is decked out with all kinds of fancy gadgets. Here's the rundown of the new orbiter's specs:
JunoCam profile. Video: NASAJuno/JPL/SwRI/YouTube
The law of "pics or it didn't happen" certainly applies with Juno's trip to Jupiter, hence the inclusion of JunoCam as part of the orbiter's payload. In addition to providing close-up optical snapshots of Jupiter's swirling cloud systems and mysterious poles, the camera is a great example of a project that uses its own limitations as an opportunity for creative solutions.
"We do not have enough data volume to take a picture on every spin," explained Cathy Hansen, the co-investigator of JunoCam, in a NASA video. "We are going to have to be choosy."
For the JunoCam team, that means inviting amateur astronomers to share their own observations and recommendations for what Jovian regions to photograph. There is even an online voting system for people who'd like to back particular points of interest.
"JunoCam is a unique element on the payload of this spacecraft, because from the outset its reason for being on the payload was to do outreach to the public," Hansen said.
Magnetometer profile. Video: NASAJuno/JPL/SwRI/YouTube
Jupiter has long been known to rock an absolutely intense and expansive magnetic field. In fact, the Jovian magnetosphere is the largest planetary structure in the solar system by volume, extending 75 times beyond the reaches of the planet itself.
A phenomenon as thoroughly epic as this sprawling magnetosphere clearly warrants its own instrument. As a result, Juno is equipped with a sophisticated magnetometer consisting of two main components: The Fluxgate Magnetometer (FGM), which will map out the direction and strength of Jupiter's magnetic field lines, and the Advanced Stellar Compass (ASC), a star-tracking navigational system that will precisely orient Juno in space. Both are placed at the end of a 12-foot-long boom that extends from Juno's main body.
"The primary purpose for our investigation is to map the magnetic field of Jupiter very accurately and try to understand how it's generated in Jupiter's electrically conducting core," said Jack Connerney, the co-investigator of the MAG instrument.Gravity Science (GS)
GS profile. Video: NASAJuno/JPL/SwRI/YouTube
One of the most fascinating and outstanding mysteries about Jupiter is whether it has a solid core, or if it boils down to a compressed gas center. Juno will set about resolving this question by taking minute measurements of the planet's gravitational field, which will in turn shed light on the mass distribution that remains hidden under Jupiter's thick cloud cover.
As it orbits the planet, Juno will send radio signals to and from a 34-meter-wide radio antenna based at the Deep Space Network in Goldstone, California. Using the Doppler effect, the GS team will measure minor gravitational distortions in this radio relay to unpack density variations within the planet.
Microwave Radiometer (MWR)
MWR profile. Video: NASAJuno/JPL/SwRI/YouTube
Jupiter is a massive ball of deadly radiation, which is why Juno's sensitive electronics have to be locked up in a vault behind thick, titanium walls. But for the six antennae that constitute the Microwave Radiometer instrument, confronting the planet's complex radiation output is the objective.
Mounted on two external flanks of the orbiter, MWR is designed to pick up six microwave frequencies. Each will reveal insights about the temperature, conditions, and water content of Jupiter's atmosphere at different depths within the planet. The radiometer is expected to pick up signals tucked away as deep as 600 kilometers (372 miles) under Jupiter's surface, providing an unprecedented glimpse of the tumultuous vistas beneath Jupiter's clouds.
Radio and Plasma Wave Sensor (WAVES)
WAVES profile. Video: NASAJuno/JPL/SwRI/YouTube
Designed to root out radio and plasma waves in Jupiter's atmosphere, Juno's WAVES instrument consists of a classic rabbit-ear-style antenna for picking up electric emissions, along with a wire coil for fluctuating magnetic waves.
The main goal for the WAVES team is to clarify the ways in which Jupiter's atmosphere interacts with its magnetic and electric fields, especially at the poles. But the instrument has also already proved to be a popular favorite after it picked up this eerie "roar" of the planet's magnetosphere a few weeks back. Needless to say, it will be interesting to see what else WAVES finds.
Magnetic "roar" of Jupiter. Video: NASA Jet Propulsion Laboratory/YouTube
Ultraviolet Imaging Spectrograph (UVS)
UVS profile. Video:NASAJuno/JPL/SwRI/YouTube
The Northern and Southern lights attract crowds of spectators at Earth's poles, but they have nothing on the spectacular auroras of Jupiter. To study these dazzling light shows, some of which exceed our planet in size, Juno is outfitted with an Ultraviolet Imaging Spectrograph that can monitor auroras across several ultraviolet (UV) wavelengths.
"It's much easier to look at [auroras] in ultraviolet wavelengths because we can see it on the day side as well," said UVS co-investigator Randy Gladstone. "When we see light from those different colors in the UV, they tell us different things about Jupiter's upper atmosphere and the particles that are causing the auroras to happen."
Jovian Infrared Auroral Mapper (JIRAM)
JIRAM profile. Video: NASAJuno/JPL/SwRI/YouTube
Jupiter's auroras and hotspots will also be monitored by the Italian-made JIRAM instrument, which will capture infrared images as a counterpoint to the ultraviolet pictures.
Jovian Auroral Distribution Experiment (JADE)
JADE profile. Video: NASAJuno/JPL/SwRI/YouTube
A particle detector called JADE is designed to scope out electron and ions within Jupiter's auroras. While UVS and JIRAM will provide images of auroral activity across several wavelengths, JADE is focused on accurately detecting the very particles that generate these ribbons of light across the planet.
The experiment consists of three electron sensors located on different sides of Juno, along with one ion sensor, which are designed to pick up the signatures of lower energy particles emitting around 30 kiloelectron volts.
Jupiter Energetic Particle Detector Instrument (JEDI)
JEDI profile. Video: NASAJuno/JPL/SwRI/YouTube
Barry Mauk, the team leader for Juno's JEDI instrument, admits that his project's acronym is a little bit "forced," but it was too good to resist for obvious reasons. And indeed, much like Jedi knights, this puck-sized detector is capable of sensing an underlying order of tiny structures in the universe, though its focus is on Jupiter's charged particles, not midichlorians (apologies for the reminder that midichlorians are a thing).
A companion to the JADE instrument, JEDI is designed to measure high energy particles ranging from 30 to 1,000,000 kiloelectron volts, which will fill out our understanding of Jupiter's magnetic and radiation environment.
"Jupiter has the most intense and interesting radiation belts," Mauk said. "It's a rotationally dominated space environment, or magnetosphere, where Earth is a solar-wind-driven space environment. By studying two different environments that are powered by different things, you can begin to isolate the physical processes that are causing these variations."
"We hope to make great discoveries there."