The JUNO spacecraft continues its mission of very close flybys of the cloud tops of Jupiter. The most recent pass was on 19 May 2017. Images downloaded from the JunoCam instrument were made available to the public. I downloaded two sets in red, green, and blue filtered grayscale. Each set was combined into color versions using Photoshop and techniques described in a previous post. The colors are my interpretation and not necessarily real.
The eruption of Mt. St. Helens in Washington State 37 years ago was a spectacular event. Upwelling of magma caused the mountain to be forced slowly and strongly from below. On the morning of 18 May, a huge landslide occurred on the north slope face of the mountain. Rock, timber, snow and ice, slid down the face. The event allowed the volcano to release pressure and begin its eruption.
Ash was projected high in the sky and was caught in the high altitude westerly winds. The dense cloud of ash drifted east blocking out the midday sun across the state. Ash settled down on communities causing confusion and havoc.
In the path of the settling ash was Manastash Ridge astronomical observatory run by the Dept. of Astronomy of the Univ. of Washington. Douglas Geisler was working at the observatory throughout the night of the 17th into the early morning hours of the 18th. He said the skies were excellent for telescope observations. He went to bed at about 5 am.
A loud ‘boom’ barely interrupted his sleep. He went back to sleep until about noon. When he got up to go outside, it was dark.
“Yikes! – There is no day. It’s completely black; thick, inky black with visibility ~10 feet (with a flashlight), & it stinks. This is the end of the world.”
In the logbook for the 19th, he noted for the record the sky condition was black & smelly. He also noted he lost 6 hours of observing due to volcano (good excuse, huh?)
He thought he might be the last survivor of the war as he remembered hearing a ‘boom’. He turned on the radio and heard ‘cha cha’ music. Why was the world playing music at the end of the world? Eventually the radio station from Yakima said that Mt. St. Helens ‘blew its wad.’ He was relieved.
It remained dark until mid-afternoon. Several inches of ash settled on the ground. Visibility improved to about 1/2 mile by dusk. He covered the telescope and instruments to prevent damage. He took some pictures of the dome and surroundings thinking he might make a lot of money on his story. But, he never followed through.
Iridium is a global network of communications satellites. The system was originally a product of Motorola. Iridium’s 66 satellites provide wireless mobile communications as they move in polar orbits at altitude of 485 mi (781 km). They are able to provide global coverage from pole to pole.
This brief video illustrates the ability of the constellation of satellites to receive a ground signal, pass it to other satellites, then deliver it to the ground in another part of the world.
The original Iridium satellites carry three highly reflective antennae as shown in the image below. Because of their mirror-like surfaces being positioned much of the time in intense bright sunlight, they sometimes reflect a bright spot of light to the ground. The ground track of the reflections is known precisely. If you happen to see it in the sky above, it grows in brightness over a few seconds and can be many times more intense that Venus and then it fades away. They are most easily seen just after sunset and before sunrise. They can also be seen in bright daylight if you know where to look.
Wikimedia | Cliff
I received an email earlier in the week telling me such a reflection, or Iridium flare, was to pass right over my house going south. In fact, another Iridium satellite in nearly the same orbit was to also flare me only 24 seconds after the first. The sky was clear the night of 13 May as I set up for a time exposure photograph.
About 45 seconds before 9:22:14 pm, I started the exposure using NightCap Pro on my iPad 2. The flare maximum occurred as predicted right on time. Coming right behind it was the next one. It passed and peaked at 9:22:38 pm. After 90 seconds I ended the time exposure.
Taken with NightCap Pro | ISS mode | 89.05 sec
How does one know when and where to look? I subscribe to a service called CalSky. It emails me when significant events like this are to occur. It offers many options and services but is not the easiest to use. There are others which are simpler. The best in my opinion for the general user is Heavens Above. In these services, you need to input your location. Heavens Above makes it easy to do by clicking on a map for your location.
Using the CalSky interface, I produced the sky chart of where the Iridium flares were going to pass. It gave this chart making it easy to know where to point my camera.
The clear evening sky offered a view of our Moon with Jupiter nearby as shown at left. Near sunset we set up the telescope and camera on tripods for closer looks. Good seeing allowed a photograph of Jupiter showing a few cloud bands as well as 3 of the 4 Galilean Moons. Ganymede was at the upper right. Europa and Io were to the lower left. Callisto was visible farther to the lower left in the telescope view. But, it didn’t show in this photo.
Usually, setting the exposure for Jupiter detail underexposes the Galilean moons and makes them not visible. Setting exposure to show the Galilean moons overexposes Jupiter. This time was a compromise.
Canon PowerShot SX60HS, ISO = 100, Shutter = 1/25s, Raw
Screenshot view via Stellarium
SpaceX, the private rocket launching company owned by Elon Musk, has had successes lately with commercial satellite launches. On 1 May 2017, they launched the military satellite NROL-76 from historic Launch Complex 39A at the Kennedy Space Center in Florida. Another major accomplishment by SpaceX is the successful landings and re-use of the stage 1 booster of the Falcon 9 rocket. This has never been done before, not even by NASA. The way I see it, that story deserves some explanation.
Watch this compilation of clips from the most recent booster landing, their 4th. The landing takes place on an unused pad not far from launch complex 39A a short distance up the coast. I wondered what flight path the stage 1 booster took to allow it to return back to this spot near the launch site. Most of its fuel had been used to get it and the stage 2 payload to high altitude, far downrange, and going very fast. The flight needed to be very efficient.
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Saturn’s north pole features a hexagon shaped pattern in the clouds driven by fast winds that wrap the planet. The hexagon is about as wide as 2 Earths. This image taken by Cassini on 2 Apr 2014 is in greyscale.
On 26 Apr 2017, Cassini passed over this same hexagon region but at a much lower altitude. This pass was the first of 22 during the coming months in the Grand Finale of the mission. It will enter the cloud tops 15 Sep 2017 to end the 20 year mission at Saturn. As Cassini made this recent close pass, it imaged the hexagon in greyscale 3 time with filters of red, green, and blue.
Using Photoshop, I combined these RGB greyscale images into one with color. The colors are not necessarily what the eye would see. They are my choices in order to enhance differences in regions and appearance. The large blue object at the bottom is like the eye of a hurricane on Earth, but much larger.
The hexagon pattern can be produced in a laboratory evidenced in this post.
Launched 15 October 1997, the Cassini Mission is in its 20th year. It reached Saturn and entered orbit on 1 July 2004. Details of the mission can be read at this Wikipedia summary. This post is mostly about the maneuvers by Cassini to change its orbit and make 22 close encounters with Saturn in what is called the Grand Finale. End of mission is scheduled for 15 Sep 2017 when the spacecraft plunges into the atmosphere of Saturn ending a long and brilliant exploration of the famous ringed planet, its rings, and 62 moons.
Clean Room Workers Ready Spacecraft | NASA | 1996
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