Artist's conception of Juno coming near Earth on a planned flyby Oct. 9, 2013. Credit: NASA
Every so often, engineers send a spacecraft in Earth’s general direction to pick up a speed boost before heading elsewhere. But sometimes, something strange happens — the spacecraft’s speed varies in an unexpected way. Even stranger, this variation happens only during some Earth flybys.
“We detected the flyby anomaly during Rosetta’s first Earth visit in March 2005,” stated Trevor Morley, a flight dynamics specialist at the European Space Agency’s European Space Operations Centre in Darmstadt, Germany.
“Frustratingly, no anomaly was seen during Rosetta’s subsequent Earth flybys in 2007 and 2011. This is a real cosmic mystery that no one has yet figured out.”
The phenomenon has been noticed in several spacecraft (both from ESA and NASA) since 1990. NASA’s NEAR asteroid spacecraft in January 1998 had the largest change, of 13 millimeters (0.5 inches) a second. The smallest variations, with NASA’s Saturn-bound Cassini in 1999 and Mercury-pointing MESSENGER in 2005, were below the threshold of measurement.
ESA won’t even speculate on what’s going on. “The experts are stumped,” the agency says in a press release.
Those experts, however, do have some ideas on how to track that down. ESOC plans to watch Juno’s flyby using a 35 meter deep-space dish in Malargüe, Argentina, as well as a 15-meter dish in Perth, Australia
“The stations will record highly precise radio-signal information that will indicate whether Juno speeds up or slows down more or less than predicted by current theories,” ESA states.
What do you think is going on? Let us know in the comments!
An artist's conception of Juno's October 9th flyby of the Earth. (Credit: NASA/JPL -Caltech).
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).
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).
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.
Junocam image of the stars that make up the "Big Dipper" asterism
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All right, it may look just like any other picture you’ve ever seen of the Big Dipper. Maybe even a little less impressive, in fact. But, unlike any other picture, this one was taken from 290 million km away by NASA’s Juno spacecraft en route to Jupiter, part of a test of its Junocam instrument! Now that’s something new concerning a very old lineup of stars!
“I can recall as a kid making an imaginary line from the two stars that make up the right side of the Big Dipper’s bowl and extending it upward to find the North Star,” said Scott Bolton, principal investigator of NASA’s Juno mission. “Now, the Big Dipper is helping me make sure the camera aboard Juno is ready to do its job.”
Diagram of the Juno spacecraft (NASA/JPL)
The image is a section of a larger series of scans acquired by Junocam between 20:23 and 20:56 UTC (3:13 to 3:16 PM EST) on March 14, 2012. Still nowhere near Jupiter, the purpose of the imaging exercise was to make sure that Junocam doesn’t create any electromagnetic interference that could disrupt Juno’s other science instruments.
In addition, it allowed the Junocam team at Malin Space Science Systems in San Diego, CA to test the instrument’s Time-Delay Integration (TDI) mode, which allows image stabilization while the spacecraft is in motion.
Because Juno is rotating at about 1 RPM, TDI is crucial to obtaining focused images. The images that make up the full-size series of scans were taken with an exposure time of 0.5 seconds, and yet the stars (brightened above by the imaging team) are still reasonably sharp… which is exactly what the Junocam team was hoping for.
“An amateur astrophotographer wouldn’t be very impressed by these images, but they show that Junocam is correctly aligned and working just as we expected”, said Mike Caplinger, Junocam systems engineer.
As well as the Big Dipper, Junocam also captured other stars and asterisms, such as Vega, Canopus, Regulus and the “False Cross”. (Portions of the imaging swaths were also washed out by sunlight but this was anticipated by the team.)
These images will be used to further calibrate Junocam for operation in the low-light environment around Jupiter, once Juno arrives in July 2016.
Read more about the Junocam test on the MSSS news page here.
As of May 10, Juno was approximately 251 million miles (404 million kilometers) from Earth. Juno has now traveled 380 million miles (612 million kilometers) since its launch on August 5, 2011 and is currently traveling at a velocity of 38,300 miles (61,600 kilometers) per hour relative to the Sun.
Juno will repeatedly dive between the planet and its intense belts of charged particle radiation, coming only 5,000 kilometers (about 3,000 miles) from the cloud tops at closest approach. (NASA/JPL-Caltech)
Launched on August 5, 2011, NASA’s Juno spacecraft will arrive at Jupiter in 2016 to study its magnetic field and atmosphere. Using its suite of science instruments Juno will peer inside the gas giant’s thick clouds, revealing hidden structures and powerful storms. To help people visualize what it means to see the invisible, JPL’s visual strategist Dan Goods created the exhibit above, titled Beneath the Surface. It’s an installation of lights, sound and fog effects that dramatically recreates what Juno will experience as it orbits Jupiter. By using their cell phone cameras, viewers can see lightning “storms” hidden beneath upper, opaque layers of “atmosphere”… in much the same way Juno will.
Goods explains: “Humans are only able to see a little, tiny sliver of what there is available in light. There’s gamma rays, microwaves, ultraviolet and infrared light also, and infrared is close enough to the visible part of the spectrum that cell phone cameras can pick it up. Cell phones normally produce more grainy photos at night because they don’t try to cut out the infrared light the way higher-end digital cameras do so in this case, the cell phone cameras are an advantage.” (Via the Pasadena Weekly.)
I had a chance to meet Dan Goods during a Tweetup event for the Juno launch at Kennedy Space Center. He’d brought a table that had magnetic elements set beneath a flat black surface, and by passing a handheld magnet over the table you could “detect” the different magnetic fields… in some cases rather strongly, even though they were all obviously invisible. It was an ingenious way that Juno’s abilities could be demonstrated in a “hands-on” manner.
Beneath the Surface takes that kind of demonstration to an entirely new level.
“I love to work with the world of things that are right in front of you but you just can’t see,” Goods said. “With Juno, there’s all this structure just under the surface of Jupiter, but humans can develop tools that help us understand things we’d never have seen before.”
The exhibit was installed at the Pasadena Museum of California Art until January 8. It will now travel to science museums around the country.
Juno’s primary goal is to improve our understanding of Jupiter’s formation and evolution. The spacecraft will spend a year investigating the planet’s origins, interior structure, deep atmosphere and magnetosphere. Juno’s study of Jupiter will help us to understand the history of our own solar system and provide new insight into how planetary systems form and develop in our galaxy and beyond.
Here’s a fantastic look at launch day for the Juno spacecraft, now on its way to Jupiter. It’s hard not to get pumped up for the mission after watching the Atlas V rocket blast into space, sending Juno on its journey. This video is courtesy the United Launch Alliance (ULA). Universe Today will have more original videos from launch day soon from our team of photographers and videographers who were on hand at Kennedy Space Center.
NASA’s new science probe to Jupiter, Juno, will make its first launch attempt on Friday, Aug. 5 at 15:34 UT (11:34 a.m. EDT) from Cape Canaveral Air Force Station in Florida. Watch it live on NASA TV’s UStream channel.
