The Juno spacecraft, heading for a July 4 rendezvous with Jupiter, when it will go into orbit around the giant planet, successfully completed a mid-course correction engine burn on Wednesday.
Scheduled to enter orbit around Jupiter in July 2016, the American space probe Juno has now broken the record as the most distant solar-powered interplanetary spacecraft ever to operate.
The previous record had been held by Rosetta. In the past most missions beyond Mars used nuclear-generated power plants, since the amount of sunlight is insufficient. However, improvements to the efficiency of solar power, combined with a lack of nuclear fuel in the U.S., has made it possible to fly missions using solar power farther from the sun.
In preparation for its arrival in orbit around Jupiter in about a year, engineers for the unmanned probe Juno have revised their planned orbital maneuvers.
Following a detailed analysis by the Juno team, NASA recently approved changes to the mission’s flight plan at Jupiter. Instead of taking 11 days to orbit the planet, Juno will now complete one revolution every 14 days. The difference in orbit period will be accomplished by having Juno execute a slightly shorter engine burn than originally planned.
The revised cadence will allow Juno to build maps of the planet’s magnetic and gravity fields in a way that will provide a global look at the planet earlier in the mission than the original plan. Over successive orbits, Juno will build a virtual web around Jupiter, making its gravity and magnetic field maps as it passes over different longitudes from north to south. The original plan would have required 15 orbits to map these forces globally, with 15 more orbits filling in gaps to make the map complete. In the revised plan, Juno will get very basic mapping coverage in just eight orbits. A new level of detail will be added with each successive doubling of the number, at 16 and 32 orbits.
The change will extend the official mission from 15 to 20 months, though I expect that even this will be extended if the spacecraft’s fuel holds out.
The large ground-based telescope ALMA has captured a series of images of the large asteroid Juno, allowing scientists to estimate its rotation and overall shape.
Linked together into a brief animation, these high-resolution images show the asteroid rotating through space as it shines in millimeter-wavelength light. “In contrast to optical telescopes, which capture the reflected light from the Sun, the new ALMA images show the actual millimeter-wavelength light emitted by the asteroid,” said Todd Hunter, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Va.
…The complete ALMA observation, which includes 10 separate images, documents about 60 percent of one rotation of the asteroid. It was conducted over the course of four hours on 19 October 2014 when Juno was approximately 295 million kilometers from Earth. In these images, the asteroid’s axis of rotation is tilted away from the Earth, revealing its southern hemisphere most prominently.
Juno, on its way to Jupiter, flew past the Earth on October 9 and made a movie.
The link has details. The video is below the fold.
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Juno has exited safe mode and is now functioning normally.
Two days after its flyby of Earth, Jupiter probe Juno remains in safe mode.
The Juno spacecraft is in a healthy and stable state, with its tractor-trailer-size solar panels pointed toward the sun. The mission team is in communication with Juno and has seen no sign of any failures in the probe’s subsystems or components, said project manager Rick Nybakken of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. So Juno’s handlers plan to take their time and do a thorough investigation before attempting to bring all of the spacecraft’s systems back online.
In other words, there is no rush to take the spacecraft out of safe mode. It is far better to figure out exactly what is going on first.
The uncertainty of science: Engineers hope Juno’s Earth flyby yesterday will help solve a mystery seen in previous flybys by unmanned probes.
Since 1990, mission controllers at ESA and NASA have noticed that their spacecraft sometimes experience a strange variation in the amount of orbital energy they pick up from Earth during flybys, a technique routinely used to fling satellites deep into our Solar System. The unexplained variation is noticed as a tiny difference in the expected speed gained (or lost) during the passage.
The variations are extremely small: NASA’s Jupiter probe ended up just 3.9 mm/s faster than expected when it swung past Earth in December 1990. The largest variation– a boost of 13.0 mm/s – was seen with NASA’s NEAR asteroid craft in January 1998. Conversely, the differences during swingbys of NASA’s Cassini in 1999 and Messenger in 2005 were so small that they could not be confirmed.
The experts are stumped.
It is likely that these small variations are related in some way with simple engineering and not some unknown feature of gravity. Nonetheless, it remains a mystery.
After the unmanned probe Juno zipped past the Earth on its way to Jupiter today, it unexpectedly went into safe mode.
Engineers continued to diagnose the issue, which occurred after Juno whipped around Earth in a momentum-gathering flyby. Up until Wednesday, Juno had been in excellent health. While in safe mode, it can communicate with ground controllers, but its activities are limited.
It is unclear at the moment why this happened.
After postponing Juno’s second midcourse correction burn last month, engineers have now successfully completed that burn.
NASA’s Juno spacecraft successfully executed a second Deep Space Maneuver, called DSM-2 last Friday, Sept. 14. The 30 minute firing of its main engine refined the Jupiter-bound spacecraft’s trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.
NASA engineers had postponed a planned midcourse maneuver of its Jupiter-bound Juno spacecraft due to unexpectedly high pressures seen in the previous engine burn.
Juno, on its way to Jupiter, took a look back and snapped this picture of the Earth/Moon double planet.
The image was taken by the spacecraft’s camera, JunoCam, on Aug. 26 when the spacecraft was about 6 million miles (9.66 million kilometers) away.
Gives us a glimpse at what our home planet will really look like to future spacefarers, either on they way out or on their way home.
Things are so good on Juno ten days after launch that mission controllers have canceled a rocket burn to adjust the spacecraft’s course.
After a delay slightly under one hour, the Jupiter probe Juno has lifted off. Check here for updates on its status.
