You might have noticed that VMC - the Mars Webcam - has been quiet recently. Don't worry: it's all expected - it's just further proof of the challenges and excitement of planetary spaceflight!
Today, Mars is at the worst point of a period known as 'solar conjunction', which means that Mars is on the exact opposite side of the Sun from Earth. Seen from the Earth at around 16:00 today, Mars appears only 0.7658 degrees from the Sun - less than the width of your finger held at arm's length!
This results in major disturbances in our communications from Earth to Mars Express and back; as a result the spacecraft has been put into an autonomous operations mode, with all activities on hold until we come out the other side.
The video above shows the Sun from the start of this year until today - with the streamer-like tendrils of its atmosphere, the corona. Coming in from the left of the video is a bright speck - Mars! Invisible here is the tiny dot of Mars Express orbiting the red planet. Our problem communicating with Mars Express comes from the fact that the radio beam from the spacecraft has to pass through this atmosphere, getting distorted on the way.
On top of that, our dish antennas on Earth have problems picking out the weak signal from Mars Express from the 'noise' of the Sun. All of this makes this period, about a month long, especially challenging for communications with all Mars missions.
To keep the spacecraft safe, we have to give it enough information for it to look after itself for the month when we are passing behind the Sun. There's simply not enough memory on the spacecraft to also include instructions on how to carry out its normal activities (including VMC imaging!) - all the space is used up with our commands on how to look after itself for a month alone, out of contact with Earth!
The video above was produced using the excellent JHelioViewer tool, developed with funding from ESA and NASA.
It shows in blue and red the view from the LASCO instrument on the ESA/NASA SOHO solar observatory mission. This instrument puts a disc in front of the Sun to block the direct light, and what can be seen is the corona, and in this case, Mars passing behind it. In the centre are images from the NASA Solar Dynamics Observatory AIA instrument, showing the blazing Sun in the middle of our solar system. -- Thomas
We would like to make a correction on our last blog update from Wednesday; Peter Wellmann had in fact submitted three versions of Mars' North Polar Regions. The corrected versions are all below. To read more about how Peter did his processing, check out the footnotes at the bottom of the page (after the jump..). Enjoy! And thanks, Peter for these impressive results. -- Daniel
The first picture shows almost all of the North Pole, surrounded in a dense cloudy haze. Craters Korolev and Alba Mons have been located easily .
“This very interesting VMC-material shows the almost complete North Polar Region and its surrounding area covered with clouds and haze. Identifying the surface details is impossible. Only Korolev crater and Alba Mons could be found. The stunning details below Alba Mons could be high reaching and dense clouds with their shadows. These gigantic clouds extend roughly over 150km. Sometimes sand storms cover the whole planet with dust, but never before have I seen Mars with such a large cloudy and hazy area. The surface structure is clearly visible only in small areas around Alba Mons, even the North Polar Cap is not detected safely, even though the pole is situated right on the terminator. The clouds show an interesting spiral structure, probably induced by coriolis force acting on air streaming out of a high pressure area on the northern hemisphere of a left spinning planet. Although there is little sharp detail in the raw-material I decided to give it a try.”
The second edit shows a similar situation as the first picture, the only difference being that they are on different sides of the hemisphere. This picture shows the complete polar region and the craters Acidalia Planitia, Lyot and Lomonosov could be clearly detected. The entire pole is covered with nicely structured clouds and haze.
“This very interesting VMC-picture should be seen as supplement to my previous submitted image 2010/11/13. It shows the part of the polar region not visible on the 2010/11/13 image. Almost the entire North Pole and surrounding area is covered with nicely structured clouds and haze. Identifying surface details is not easily accomplished. Only Acidalia Planitia is partly free of clouds, and Lomonosov crater can be easily detected. On a second look the large crater Lyot is seen full size inside a semicircle of clouds. Some other structures are easily detected by comparing with the Celestia image, but we do not know their names. Surface structure is clearly visible only in small areas, even the north polar cap is not detected safely, although the pole is situated right below the terminator. The clouds show an interesting spiral structure, in a large stripe to the left very fine structure is visible. Although there is little sharp detail in the raw-material I decided to give it a try.”
The final image is of the complete North Pole covered in a nicely structured haze. The two pictures of Mars were taken about 4 days apart. Some landmarks were identified under the cloud haze.
“This picture combines two VMC-operations; the first took place on 2010/11/23, the second only four days later on 2010/11/27. Both operations meet a time with strong cloud and haze-activity on the northern part of Mars. By comparing these images, my idea was to show the rapid change in cloud-structure. Due to the hidden surface it is not easy to identify landmarks, but I was able to locate some prominent craters for better orientation comparing the two images.
Processing colour from the original raw-frames by using the supplied flat-field, the atmospheric structures come out gray/white and not yellow/brown, so I assume they mainly are clouds and haze, not sandstorms. It is amazing how different these structures look, in some areas they look rather smooth, and in other areas they show very fine details. There also seems to be a difference between dawn and dusk, just compare the left (dusk) and right (dawn) terminator in the region of the “horn”. Also it seems that surface conditions affect cloud structure above. Processing these pictures was not easy and time consuming, but looking at the result I think time was not wasted. I do like this picture.”