7 Days Out From Orbital Insertion, NASA’s Juno Images Jupiter and its Largest Moons

This annotated color view of Jupiter and its four largest moons -- Io, Europa, Ganymede and Callisto -- was taken by the JunoCam camera on NASA's Juno spacecraft on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) from Jupiter. Image credit: NASA/JPL-Caltech/MSSS
This annotated color view of Jupiter and its four largest moons — Io, Europa, Ganymede and Callisto — was taken by the JunoCam camera on NASA’s Juno spacecraft on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) from Jupiter. Image credit: NASA/JPL-Caltech/MSSS

Now just 7 days out from a critical orbital insertion burn, NASA’s Jupiter-bound Juno orbiter is closing in fast on the massive gas giant. And as its coming into focus the spacecraft has begun snapping a series of beautiful images of the biggest planet and its biggest moons.

In a newly released color image snapped by the probes educational public outreach camera named Junocam, banded Jupiter dominates a spectacular scene that includes the giant planet’s four largest moons — Io, Europa, Ganymede and Callisto.

Junocam’s image of the approaching Jovian system was taken on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) and hints at the multitude of photos and science riches to come from Juno.

“Juno on Jupiter’s Doorstep,” says a NASA description. “And the alternating light and dark bands of the planet’s clouds are just beginning to come into view,” revealing its “distinctive swirling bands of orange, brown and white.”

This color view of Jupiter and its four largest moons -- Io, Europa, Ganymede and Callisto -- was taken by the JunoCam camera on NASA's Juno spacecraft on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) from Jupiter. Image credit: NASA/JPL-Caltech/MSSS
This color view of Jupiter and its four largest moons — Io, Europa, Ganymede and Callisto — was taken by the JunoCam camera on NASA’s Juno spacecraft on June 21, 2016, at a distance of 6.8 million miles (10.9 million kilometers) from Jupiter. Image credit: NASA/JPL-Caltech/MSSS

Rather appropriately for an American space endeavor, the fate of the entire mission hinges on do or die ‘Independence Day’ fireworks.

On the evening of July 4, Juno must fire its main engine for 35 minutes.

The Joy of JOI – or Jupiter Orbit Insertion – will place NASA’s robotic explorer into a polar orbit around the gas giant.

The approach over the north pole is unlike earlier probes that approached from much lower latitudes nearer the equatorial zone, and thus provide a perspective unlike any other.

After a five-year and 2.8 Billion kilometer (1.7 Billion mile) outbound trek to the Jovian system and the largest planet in our solar system and an intervening Earth flyby speed boost, the moment of truth for Juno is now inexorably at hand.

This colorized composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
This colorized composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

And preparations are in full swing by the science and engineering team to ensure a spectacular Fourth of July fireworks display.

The team has been in contact with Juno 24/7 since June 11 and already uplinked the rocket firing parameters.

Signals traveling at the speed of light take 10 minutes to reach Earth.

The protective cover that shields Juno’s main engine from micrometeorites and interstellar dust was opened on June 20.

“And the software program that will command the spacecraft through the all-important rocket burn was uplinked,” says NASA.

The pressurization of the propulsion system is set for June 28.

“We have over five years of spaceflight experience and only 10 days to Jupiter orbit insertion,” said Rick Nybakken, Juno project manager from NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.

“It is a great feeling to put all the interplanetary space in the rearview mirror and have the biggest planet in the solar system in our windshield.”

On the night of orbital insertion, Juno will fly within 2,900 miles (4,667 kilometers) of the Jovian cloud tops.

All instruments except those critical for the JOI insertion burn on July 4, will be tuned off on June 29. That includes shutting down Junocam.

“If it doesn’t help us get into orbit, it is shut down,” said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio.

“That is how critical this rocket burn is. And while we will not be getting images as we make our final approach to the planet, we have some interesting pictures of what Jupiter and its moons look like from five-plus million miles away.”

During a 20 month long science mission – entailing 37 orbits lasting 11 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.

“Jupiter is the Rosetta Stone of our solar system,” says Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”

During the orbits, Juno will probe beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.

Junocam has already taken some striking images during the Earth flyby gravity assist speed boost on Oct. 9, 2013.

For example the dazzling portrait of our Home Planet high over the South American coastline and the Atlantic Ocean.

For a hint of what’s to come, see our colorized Junocam mosaic of land, sea and swirling clouds, created by Ken Kremer and Marco Di Lorenzo.

NASA's Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina,  South America and the southern Atlantic Ocean. Raw imagery was reconstructed and aligned by Ken Kremer and Marco Di Lorenzo, and false-color blue has been added to the view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
NASA’s Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina, South America and the southern Atlantic Ocean. Raw imagery was reconstructed and aligned by Ken Kremer and Marco Di Lorenzo, and false-color blue has been added to the view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

As Juno sped over Argentina, South America and the South Atlantic Ocean it came within 347 miles (560 kilometers) of Earth’s surface.

During the flyby, the science team observed Earth using most of Juno’s nine science instruments since the slingshot also serves as an important dress rehearsal and key test of the spacecraft’s instruments, systems and flight operations teams.

Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com
Juno soars skyward to Jupiter on Aug. 5, 2011 from launch pad 41 at Cape Canaveral Air Force Station at 12:25 p.m. EDT. View from the VAB roof. Credit: Ken Kremer/kenkremer.com

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.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Ken Kremer

Juno spacecraft and its science instruments. Image credit: NASA/JPL
Juno spacecraft and its science instruments. Image credit: NASA/JPL
Juno graphic
Juno orbital graphic

Mariner 10: Best Venus Image and 1st Ever Planetary Gravity Assist – 40 Years Ago Today

Exactly 40 Years ago today on Feb. 5, 1974, Mariner 10, accomplished a history making and groundbreaking feat when the NASA science probe became the first spacecraft ever to test out and execute the technique known as a planetary gravity assisted flyby used to alter its speed and trajectory – in order to reach another celestial body.

Mariner 10 flew by Venus 40 years ago to enable the probe to gain enough speed and alter its flight path to eventually become humanity’s first spacecraft to reach the planet Mercury, closest to our Sun.

Indeed it was the first spacecraft to visit two planets.

During the flyby precisely four decades ago, Mariner 10 snapped its 1st close up view of Venus – see above.

From that moment forward, gravity assisted slingshot maneuvers became an extremely important technique used numerous times by NASA to carry out planetary exploration missions that would not otherwise have been possible.

For example, NASA’s twin Voyager 1 and 2 probes launched barely three years later in 1977 used the gravity speed boost to conduct their own historic flyby expeditions to our Solar Systems outer planets.

Mariner 10's Mercury.  This is a photomosaic of images collected by Mariner 10 as it flew past Mercury on 29 March 1974.  It shows the southern hemisphere.  The spacecraft took more than 7,000 images of Mercury, Venus, the Earth, and the moon during its mission.  Credit: NASA
Mariner 10’s Mercury.
This is a photomosaic of images collected by Mariner 10 as it flew past Mercury on 29 March 1974. It shows the southern hemisphere. The spacecraft took more than 7,000 images of Mercury, Venus, the Earth, and the moon during its mission. Credit: NASA

Without the flyby’s, the rocket launchers thrust by themselves did not provide sufficient interplanetary speed to reach their follow on targets.

NASA’s Juno Jupiter orbiter just flew back around Earth this past October 9, 2013 to gain the speed it requires to reach the Jovian system.

The Mariner 10 probe used an ultraviolet filter in its imaging system to bring out details in the Venusian clouds which are otherwise featureless to the human eye – as you’ll notice when viewing it through a telescope.

Venus surface is completely obscured by a thick layer of carbon dioxide clouds.

The hellish planet’s surface temperature is 460 degrees Celsius or 900 degrees Fahrenheit.

Diagram of Mariner 10 which flew by Venus and Mercury in 1974 and 1975. This photo identifies various parts of the spacecraft and the science instruments, which were used to study the atmospheric, surface, and physical characteristics of Venus and Mercury. This was the sixth in the series of Mariner spacecraft that explored the inner planets beginning in 1962. Credit: Jet Propulsion Laboratory
Diagram of Mariner 10 which flew by Venus and Mercury in 1974 and 1975. This photo identifies various parts of the spacecraft and the science instruments, which were used to study the atmospheric, surface, and physical characteristics of Venus and Mercury. This was the sixth in the series of Mariner spacecraft that explored the inner planets beginning in 1962. Credit: Jet Propulsion Laboratory

Following the completely successful Venus flyby, Mariner 10 eventually went on to conduct a trio of flyby’s of Mercury in 1974 and 1975.

It imaged nearly half of the planets moon-like surface, found surprising evidence of a magnetic field, discovered that a metallic core comprised nearly 80 percent of the planet’s mass, and measured temperatures ranging from 187°C on the dayside to minus 183°C on the nightside.

Mercury was not visited again for over three decades until NASA’s MESSENGER flew by and eventually orbited the planet – and where it remains active today.

Mariner 10 was launched on Nov. 3, 1973 from the Kennedy Space Center atop an Atlas-Centaur rocket.

Mosaic of the Earth from Mariner 10 after launch. Credit: NASA
Mosaic of the Earth from Mariner 10 after launch. Credit: NASA
Shortly after blastoff if also took photos of the Earth and the Moon.

Ultimately it was the last of NASA’s venerable Mariner planetary missions hailing from the dawn of the Space Age.

Mariner 11 and 12 were descoped due to congressional budget cuts and eventually renamed as Voyager 1 and 2.

The Mariner 10 science team was led by Bruce Murray of the Jet Propulsion Laboratory (JPL), Pasadena, Calif.

Murray eventually became the Director of JPL. After he passed away in 2013, key science features on Martian mountain climbing destinations were named in his honor by the Opportunity and Curiosity Mars rover science teams.

Stay tuned here for Ken’s continuing LADEE, Chang’e-3, Orion, Orbital Sciences, SpaceX, commercial space, Mars rover and more planetary and human spaceflight news.

Ken Kremer

Mariner 10 trajectory and timeline to Venus and Mercury. Credit: NASA
Mariner 10 trajectory and timeline to Venus and Mercury. Credit: NASA
Diagram of the Mariner series of spacecraft and launch vehicle. Mariner spacecraft explored Mercury, Venus and Mars. Credit: Jet Propulsion Laboratory
Diagram of the Mariner series of spacecraft and launch vehicle. Mariner spacecraft explored Mercury, Venus and Mars. Credit: Jet Propulsion Laboratory
This false color composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
Mosaic of Earth from Juno gravity assist Flyby in 2013 –
compare to Mariner 10 Earth mosaic above from 1973 to see advances in space technology
This false color composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

Jupiter Bound Juno snaps Dazzling Gallery of Planet Earth Portraits

Juno Portrait of Earth
This false color composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
See below a gallery of Earth from Juno[/caption]

During a crucial speed boosting slingshot maneuver around Earth on Oct. 9, NASA’s Jupiter-bound Juno probe snapped a dazzling gallery of portraits of our Home Planet over the South American coastline and the Atlantic Ocean. See our mosaics of land, sea and swirling clouds above and below, including several shown in false color.

But an unexpected glitch during the do or die swing-by sent the spacecraft into ‘safe mode’ and delayed the transmission of most of the raw imagery and other science observations while mission controllers worked hastily to analyze the problem and successfully restore Juno to full operation on Oct. 12 – but only temporarily!

Because less than 48 hours later, Juno tripped back into safe mode for a second time. Five days later engineers finally recouped Juno and it’s been smooth sailing ever since, the top scientist told Universe Today.

“Juno is now fully operational and on its way to Jupiter,” Juno principal investigator Scott Bolton told me today. Bolton is from the Southwest Research Institute (SwRI), San Antonio, Texas.

“We are completely out of safe mode!”

NASA's Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina,  South America and the southern Atlantic Ocean. Raw imagery was reconstructed and aligned by Ken Kremer and Marco Di Lorenzo, and false-color blue has been added to the view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
NASA’s Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina, South America and the southern Atlantic Ocean. Raw imagery was reconstructed and aligned by Ken Kremer and Marco Di Lorenzo, and false-color blue has been added to the view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

With the $1.1 Billion Juno probe completely healthy once again and the nail-biting drama past at last, engineers found the time to send the stored photos and research data back to ground station receivers.

“The science team is busy analyzing data from the Earth flyby,” Bolton informed me.

The amateur image processing team of Ken Kremer and Marco Di Lorenzo has stitched together several portraits from raw images captured as Juno sped over Argentina, South America and the South Atlantic Ocean and within 347 miles (560 kilometers) of the surface. We’ve collected the gallery here for all to enjoy.

Several portraits showing the swirling clouds and land masses of the Earth’s globe have already been kindly featured this week by Alan Boyle at NBC News and at the Daily Mail online.

NASA's Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina,  South America and the southern Atlantic Ocean. Raw imagery was stitched by Ken Kremer and Marco Di Lorenzo in this view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
NASA’s Juno probe captured the image data for this composite picture during its Earth flyby on Oct. 9 over Argentina, South America and the southern Atlantic Ocean. Raw imagery was stitched by Ken Kremer and Marco Di Lorenzo in this view taken by a near-infrared filter that is typically used to detect methane. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

Raw images from the Junocam camera are collected in strips – like a push broom. So they have to be carefully reconstructed and realigned to match up. But it can’t be perfect because the spacecraft is constantly rotating and its speeding past Earth at over 78,000 mph.

So the perspective of Earth’s surface features seen by Junocam is changing during the imaging.

And that’s what is fascinating – to see the sequential view of Earth’s beautiful surface changing as the spacecraft flew over the coast of South America and the South Atlantic towards Africa – from the dayside to the nightside.

This composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
This composite shows more than half of Earth’s disk over the coast of Argentina and the South Atlantic Ocean as the Juno probe slingshotted by on Oct. 9, 2013 for a gravity assisted acceleration to Jupiter. The mosaic was assembled from raw images taken by the Junocam imager. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

It’s rare to get such views since only a few spacecraft have swung by Earth in this manner – for example Galileo and MESSENGER – on their way to distant destinations.

Coincidentally this week, the Cygnus cargo carrier departed the ISS over South America.

Fortunately, the Juno team knew right from the start that the flyby of Earth did accomplish its primary goal of precisely targeting Juno towards Jupiter – to within 2 kilometers of the aim point, despite going into safe mode.

“We are on our way to Jupiter as planned,” Juno Project manager Rick Nybakken, told me in a phone interview soon after the flyby of Earth. Nybakken is from NASA’s Jet Propulsion Lab in Pasadena, CA.

“None of this affected our trajectory or the gravity assist maneuver – which is what the Earth flyby is,” he said.

Juno swoops over Argentina  This reconstructed day side image of Earth is one of the 1st snapshots transmitted back home by NASA’s Jupiter-bound Juno spacecraft during its speed boosting flyby on Oct. 9, 2013. It was taken by the probes Junocam imager and methane filter at 12:06:30 PDT and an exposure time of 3.2 milliseconds. Juno was flying over South America and the southern Atlantic Ocean. The coastline of Argentina is visible at top right. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer
Juno swoops over Argentina
This reconstructed day side image of Earth is one of the 1st snapshots transmitted back home by NASA’s Jupiter-bound Juno spacecraft during its speed boosting flyby on Oct. 9, 2013. It was taken by the probes Junocam imager and methane filter at 12:06:30 PDT and an exposure time of 3.2 milliseconds. Juno was flying over South America and the southern Atlantic Ocean. The coastline of Argentina is visible at top right. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer

It also accelerated the ships velocity by 16,330 mph (26,280 km/h) – thereby enabling Juno to be captured into polar orbit about Jupiter on July 4, 2016.

Dayside view of a sliver of Earth snapped by Juno during flyby on Oct. 9, 2013.  This mosaic has stitched from raw image data captured by methane near-infrared filter on Junocam imager at 11:57:30 PDT.  Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
Dayside view of a sliver of Earth snapped by Juno during flyby on Oct. 9, 2013. This mosaic is stitched from raw image data captured by methane near-infrared filter on Junocam imager at 11:57:30 PDT. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

The safe mode did not impact the spacecraft’s trajectory one smidgeon!

It was likely initiated by an incorrect setting for a fault protection trigger for the spacecraft’s battery when Juno was briefly in an eclipse during the flyby.

Nybakken also said that the probe was “power positive and we have full command ability,” while it was in safe mode.

Safe mode is a designated fault protective state that is preprogrammed into spacecraft software in case something goes amiss. It also aims the craft sunwards thereby enabling the solar arrays to keep the vehicle powered.

False-color composite of a sliver of Earth snapped by Juno during flyby on Oct. 9, 2013.  This mosaic is stitched from raw image data captured by methane near-infrared filter on Junocam imager at 11:57:30 PDT.  Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo
False-color composite of a sliver of Earth snapped by Juno during flyby on Oct. 9, 2013. This mosaic is stitched from raw image data captured by methane near-infrared filter on Junocam imager at 11:57:30 PDT. Credit: NASA/JPL/SwRI/MSSS/Ken Kremer/Marco Di Lorenzo

The Earth flyby maneuver was necessary because the initial Atlas V rocket launch on Aug. 5, 2011 from Cape Canaveral Air Force Station, FL was not powerful enough to place Juno on a direct trajectory flight to Jupiter.

As of today, Juno is more than was 6.7 million miles (10.8 million kilometers) from Earth and 739 million miles (7.95 astronomical units) from Jupiter. It has traveled 1.01 billion miles (1.63 billion kilometers, or 10.9 AU) since launch.

With Juno now on course for our solar system’s largest planet, there won’t be no any new planetary images taken until it arrives at the Jovian system in 2016. Juno will then capture the first ever images of Jupiter’s north and south poles.

We have never seen Jupiter’s poles imaged from the prior space missions, and it’s not possible from Earth.

During a year long mission at Jupiter, Juno will use its nine science instruments to probe deep inside the planet to reveal its origin and evolution.

“Jupiter is the Rosetta Stone of our solar system,” says Bolton. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”

Based on what we’ve seen so far, Junocam is sure to provide spectacular views of the gas giants poles and cloud tops.

Only 982 days to go !

Ken Kremer

Credit: NASA/JPL
Credit: NASA/JPL

Spotting Juno: NASA’s Jupiter-bound Spacecraft Gets a Boost from Earth on October 9th, 2013

Psst! Live in South Africa and read Universe Today? Then you might just get a peak at the Juno spacecraft as it receives a boost from our fair planet on the evening of October 9th, 2013.

Launched from Cape Canaveral Air Force Station on August 5th, 2011 atop an Atlas 5 rocket in a 551 configuration, Jupiter-bound Juno is approaching the Earth from interior to its orbit over the next month. Its closest approach to the Earth during its October 9th flyby will occur at 19:21 Universal Time (UT) which is 3:21 PM Eastern Daylight Saving Time. The spacecraft will pass 559 kilometres over the South Atlantic to a point 200 kilometres off of the southeastern coast of South Africa at latitude -34.2° south & longitude 34° east.

For context, this is just about 25% higher than the International Space Station orbits at an average of 415 kilometres above the Earth. The ISS is 108.5 metres across on its longest dimension, and we wouldn’t be surprised if Juno were a naked eye object for well placed observers watching from a dark sky site around Cape Town, South Africa. Especially if one of its three enormous 8.9 metre long solar panels were to catch the Sun and flare Iridium-style!

Two minutes before closest approach, Juno will experience the only eclipse of its mission, passing into the umbra of Earth’s shadow for about 20 minutes. Chris Peat at Heavens-Above also told Universe Today that observers in India are also well-placed to catch sight of Juno with binoculars after it exits the Earth’s shadow.

Juno passed its half-way mark to Jupiter last month on August 12th when the “odometer clicked over” to 9.464 astronomical units. Juno will enter orbit around Jupiter on July 4th, 2016. Juno will be the second spacecraft after Galileo to permanently orbit the largest planet in our solar system.

The passage of Juno through the Earth's shadow on October 9th, 2013. (Credit and Copyright: Heavens-Above, used with permission).
The passage of Juno through the Earth’s shadow on October 9th, 2013. (Credit and Copyright: Heavens-Above, used with permission).

Catching a flyby of Juno will be a unique event. Unfortunately, the bulk of the world will miss out, although you can always vicariously fly along with Juno with Eyes on the Solar System. Juno is currently moving about 7 km/s relative to the Earth, and will move slightly faster than the ISS in its apparent motion across the sky from west to east before hitting Earth’s shadow. This slingshot will give Juno a 70% boost in velocity to just under 12km/s relative to Earth, just slower than Pioneer 10’s current motion relative to the Sun of 12.1km/s.

At that speed, Juno will be back out past the Moon in about 10 hours after flyby. There’s a chance that dedicated imagers based along North American longitudes could still spy Juno later that evening.

Juno approaches the Earth from the direction of the constellation Libra and will recede from us in the direction of the constellation Perseus on the night of October 9th.

The ground track covered by Juno as it passes by the Earth. (Credit & Copyright: Heavens-Above, used with permission).
The ground track covered by Juno as it passes by the Earth. (Credit & Copyright: Heavens-Above, used with permission).

There’s also a precedent for spotting such flybys previous. On August 18th, 1999, NASA’s Cassini spacecraft made a flyby of the Earth at 1,171 kilometres distant, witnessed by observers based in the eastern Pacific region. Back then, a fuss had been raised about the dangers that a plutonium-powered spacecraft might posed to the Earth, should a mis-calculation occur. No such worries surround Juno, as it will be the first solar-powered spacecraft to visit the outer solar system.

And NASA wants to hear about your efforts to find and track Juno during its historic 2013 flyby of the Earth. JPL Horizons lists an ephemeris for the Juno spacecraft, which is invaluable for dedicated sky hunters. You can tailor the output for your precise location, then aim a telescope at low power at the predicted right ascension and declination at the proper time, and watch. Precise timing is crucial; I use WWV shortwave radio broadcasting out of Fort Collins, Colorado for ultra-precise time when in the field.

As of this writing, there are no plans to broadcast the passage of Juno live, though I wouldn’t be surprised if someone like Slooh decides to undertake the effort. Also, keep an eye on Heavens-Above, as they may post sighting opportunities as well. We’ll pass ‘em along if they surface!

Late Breaking: And surface they have… a page dedicated to Juno’s flyby of Earth is now up on Heavens-Above.

Juno is slated to perform a one year science mission studying the gravity and magnetic field of Jupiter as well as the polar magnetosphere of the giant planet. During this time, Juno will make 33 orbits of Jupiter to complete its primary science mission. Juno will study the environs of Jupiter from a highly inclined polar orbit, which will unfortunately preclude study of its large moons. Intense radiation is a primary hazard for spacecraft orbiting Jupiter, especially one equipped with solar panels. Juno’s core is shielded by one centimetre thick titanium walls, and it must thread Jupiter’s radiation belts while passing no closer than 4,300 kilometres above the poles on each pass. One run-in with the Io Plasma Torus would do the spacecraft in. Like Galileo, Juno will be purposely deorbited into Jupiter after its primary mission is completed in October 2017.

If you live in the right location, be sure to check out Juno as it visits the Earth, one last time. We’ll keep you posted on any live broadcasts or any further info on sighting opportunities as October 9th draws near!

– Got pics of Juno on its flyby of the Earth? Send ’em in to Universe Today!

– You can also follow the mission on Twitter as @NASAJuno.