Tuesday, July 22, 2014

A Voyager 2 View of Europa

As Voyager 2 approached Europa, this was the highest resolution global view it obtained before Europa filled more than the entire frame.  Europa was still quite small in the field of view at this point (the time in between this and the global mosaics it would later take was spent studying other targets), and, given the intricate, low contrast nature of its surface, this made this dataset very hard to work with.  It was taken on July 8, 1979, from a range of about 1.2 million kilometers. 

Raw data courtesy NASA/JPL, Processed images Copyright Ted Stryk

Sunday, July 20, 2014

Standing on Venus in 1975

Getting the thrill of seeing what it would be like to stand on another planet is one of the big thrills of planetary exploration.  This year, we have gotten to stand on the Moon thanks to Chang'e 3 and the short trek of the Yutu rover.  We have also gotten to ride along and tour Mars with Curiosity and Opportunity.  Later this year, the Philae lander will allow us to stand on a comet. 

This August, it will be 44 years since the first probe to send data from the surface of another planet (ignoring atmospheric probes and failed landers - key word is "surface") plunked down on the surface of Venus. Venera 7 did not function well after landing, sending back only temperature and pressure data. It was followed in 1972 by Mars 3, which briefly sent a signal from the surface of Mars before failing, and Venera 8, a highly successful Venus lander but one that did not carry a camera. Veneras 7 and 8 informed us, but they didn't allow us the feeling of being there.

In 1975, Veneras 9 and 10 became the first landers to image the surface of another planet, scanning 180-degree panoramas during the ~ hour that each lander functioned on the surface.  Stacking available data, this is what Venera 9 saw when, on October 22 1975, it landed (I've posted this previously, but am posting it again for context).

On October 25, Venera 10 followed.

The cameras scanned the scene one pixel at a time.  Given the rate at which the image could be taken and transmitted and the available amount of time, the images had to be of low resolution, even for the time. Given these limits, there were several options.  One would have been to image a very narrow area at high resolution from the lander base to the horizon, but that would have been hard to interpret.  Scanning from surface to horizon over a large area would have been so coarse that again, it would have had limited value.  The compromise worked out was that the camera would scan in a U-shape, meaning that the tips of the panorama would look at the horizon, while the middle would look down ant the base of the lander.

For science, this worked well. Visually, however, they are unnatural.  Of course these panoramas can be rectified to show the surface at a more natural angle.  Still, this leaves the center, the focal area of the images, as a gaping hole, and is thus visually unsatisfying. In the past, I tried to make views out out of corrected corners of the images, but these proved too small to do much with and were still very awkward.  After seeing Don Mitchell's excellent work on Venera 13 and 14 data, I got the idea of creating an image for both landers created by sampling each image at different distances from the lander to create a "proper" picture.  The objects in the image would be real, though the arrangement would not.  However, given that the original images are only 128x512 pixels (and not all of that shows the surface), making this convincing was very difficult (Venera 13 and 14 took panoramas on both sides of the lander and at much higher resolution, allowing much more image data to sample).  The first attempt was a failure.

I recently tried again.  This time, I accepted the fact that, in the case of Venera 9, I would have to use somewhat distorted versions of the same rocks at times to make a sufficiently big image.  I still don't love the result, but given the limited data and the complexity of the landscape, it is the best I've been able to do. The fact that the illumination is clearly different on the left-hand side and the right hand side of the panorama exacerbates the problems.  Still, it makes for a neat view. 

And here is the same view with Venera 13-based color.  

 Venera 10 is much more pleasing.  The flatter surface made illumination less of an issue.  It was also easier to resample areas without being obvious.  

And here, again, is the same view with Venera 13-based color. 

 Clearly, these are in no way scientific products.  But they do, I think, allow us to get a bit of the true feel of what it is like to stand on these two very different locations on the surface of Venus.  And as our nearly 39-year old first views from the surface of another planet, they deserve that.  

Lastly, since I found the ideal size for these to be 400x275, I made some composites(black and white and color) that are larger (in these cases, I enlarged the new images to match the panoramas. 

Data Courtesy the Russian Academy of Sciences, Processed Images Copyright Ted Stryk

Thirty-eight years ago today: Viking 1 lands on Mars.

In recognition of the first successful Mars lander, I am posting two views from Viking 1 that I have processed.

Raw data courtesy NASA/JPL, Processed images Copyright Ted Stryk

Tuesday, December 03, 2013

40 Years Ago: Pioneer 10 Flies By Jupiter

In the last entry, I posted a crescent view of Jupiter from Pioneer 10, on this, the 40th anniversary of the closest approach (December 3, 1973), I decided to share this view of Jupiter from the approach phase.  As time permits, I hope to do more with this dataset.

Processed Image Copyright Ted Stryk, Data Courtesy NASA/Ames Research Center.  A special thanks to the Ames Research Center history office for helping me find the data used in making this. 

Friday, August 02, 2013

Jupiter and Io from Pioneer 10

This is a parting shot of Jupiter and Io, taken December 5, 1973, by the Pioneer 10 spacecraft, the first to see either world as a crescent.  This image was generated with red and blue channel data from the spacecraft's imaging photopolarimeter (image set B26, for anyone wondering), which scanned the planet as the spacecraft rotated.  The maximum scan length was only 466 pixels, leading to postage-stamp sized images that are often blown up to ridiculous sizes.  This image is shown at a significantly larger scale than its original size for clarity, and extra black sky has been added for effect.  The data for this image was of rather poor quality, especially on the red channel.   Still, it is a nice reminder of one of the most overlook "firsts" in solar system exploration.

 Processed Image Copyright Ted Stryk, Data Courtesy NASA/Ames Research Center.  A special thanks to the Ames Research Center history office for helping me find the data used in making this. 

Friday, April 05, 2013

The Land Between Triton's Frozen Lakes

One of the biggest discoveries of the last decade has been the discovery of unfrozen lakes on Saturn's moon Titan.  This was the last good chance we had at finding standing liquid and non-transient streams and rivers on the surface of any extraterrestrial world in in our solar system, Io's lakes of magma nonwithstanding.  Such things had clearly existed in the past, but were either dried up or frozen over.  Back in 1989, there were hopes that we would find lakes of liquid nitrogen on on Neptune's moon Triton.   And indeed, it had produced such lakes, but they have since frozen over.   Fortunately, a pair of these lakes were in the area that received the best coverage from Voyager.   This included a narrow "bridge" that separated the pair, which was included in four of the highest resolution images of Triton obtained. This allowed me to stack them to reduce noise and improve clarity (although not all of them include the whole area covered here).  I wasn't able to get (or expecting to get) a great improvement over my previous processing efforts or those of others, but there is a moderate gain in clarity.  To be honest, I took this on for an April Fools prank, but I couldn't decide on how to approach that on time.   Still, since I went to the trouble of doing the processing work, I figured I'd share the result. It is shown at ~375 m/pixel.

 Processed Image Copyright Ted Stryk, Raw Data Courtesy NASA/JPL