Sounds of Jupiter’s Aurora

The frequency range of these signals is from 7 to 140 kilohertz. Radio astronomers call these “kilometric emissions” because their wavelengths are about a kilometer long.

Let’s see, the wavelength of a 7 kHz signal is:

λ = speed of light (c) / 7 kHz or 7000 hertz

or

λ = 300,000,000 m/s / 7,000 Hz

λ = 42,857 m or 42.857 km

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Sentinel-1A Damaged

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The power producing solar panels on the Sentinel-1A satellite have been damaged by an impact of some sort. The impacting object was tiny, in the few-millimetres class tiny. The image above from ESA shows the damage.

Even an impact with such a tiny object makes a difference:

A sudden small power reduction was observed in a solar array of Sentinel-1A, orbiting at 700 km altitude, at 17:07 GMT on 23 August. Slight changes in the orientation and the orbit of the satellite were also measured at the same time. — ESA

Sentinel 1A operations have not been impacted. There are in excess of 19,000 bits of known space debris, luckily this one was small.

The in-depth story from ESA.

Launch Day

Later today NASA will launch the OSIRIS-REx spacecraft will lift off on a mission to study an asteroid in unprecedented detail. The study will include taking a small sample of asteroid Bennu and returning it to Earth for firsthand analysis.

The launch has about an 80 percent chance go due to weather at the Kennedy Space Center at 19:05 EDT / 23:05 UTC.

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A LIVE LINK WILL BE POSTED ABOUT AN HOUR BEFORE LAUNCH

More Refracted Rings

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The citizens of Earth have spacecraft orbiting the two largest planets in our solar system. Juno of course is just getting going and has entered its second of 37 orbits – plenty to come, Cassini on the other hand has been at Saturn since 2004 and is still going strong.

From the Cassini team:

Saturn’s rings appear to bend as they pass behind the planet’s darkened limb due to refraction by Saturn’s upper atmosphere.

The effect is the same as that seen in an earlier Cassini view (see PIA20491), except this view looks toward the unlit face of the rings, while the earlier image viewed the rings’ sunlit side.

The difference in illumination brings out some noticeable differences. The A ring is much darker here, on the rings’ unlit face, since its larger particles primarily reflect light back toward the sun (and away from Cassini’s cameras in this view). The narrow F ring (at bottom), which was faint in the earlier image, appears brighter than all of the other rings here, thanks to the microscopic dust that is prevalent within that ring. Small dust tends to scatter light forward (meaning close to its original direction of travel), making it appear bright when backlit. (A similar effect has plagued many a driver with a dusty windshield when driving toward the sun.)

This view looks toward the unilluminated side of the rings from about 19 degrees below the ring plane. The image was taken in red light with the Cassini spacecraft narrow-angle camera on July 24, 2016.

The view was acquired at a distance of approximately 527,000 miles (848,000 kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 169 degrees. Image scale is 3 miles (5 kilometers) per pixel.

Images: NASA/JPL-Caltech/Space Science Institute

Philae Found!

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Philae has been found! Click the image above to see an annotated version.

The find is very timely, on 30 September 2016, Rosetta will make the final rendezvous with the comet.

From ESA:
Close-up of the Philae lander, imaged by Rosetta’s OSIRIS narrow-angle camera on 2 September 2016 from a distance of 2.7 km. The image scale is about 5 cm/pixel. Philae’s 1 m-wide body and two of its three legs can be seen extended from the body. The images also provide proof of Philae’s orientation.

The image is a zoom from a wider-scene, and has been interpolated.

More information: Philae found!

Image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Jupiter’s Southern Aurora

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This image comes to us from Juno as it was going by Jupiter a few days ago on 27 August 2016. We are not getting a good look at this from Earth due to our planetary geometry, so this look from Juno is as unique as it is spectacular.

Juno’s Jovian Infrared Auroral Mapper (JIRAM) camera acquired the view at wavelengths ranging from 3.3 to 3.6 microns — the wavelengths of light emitted by excited hydrogen ions in the polar regions. The view is a mosaic of three images taken just minutes apart from each other, about four hours after the perijove pass while the spacecraft was moving away from Jupiter. — NASA

Image: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM