In August 1981, I was covering events at the Jet Propulsion Laboratory for the Voyager 2 Saturn encounter. Voyager took thousands of photos during each planetary flyby. Most of those photos have never been seen by the public and the photo archives for Voyager are not available on the Internet as are current missions such as the Mars Exploration Rovers or Cassini.

In the press room at the Von Karman Auditorium, JPL had set up several television sets that were constantly tuned to the images being received by Voyager, In other words, when Voyager snapped a photo, the image was available at the same moment in the press room as it was to the project scientists.

Throughout the days of a close encounter period, members of the press often gathered around these sets to see the latest from the outer solar system. Speculation would always be rampant about what was being seen and at the official press conferences, the scientists even sometimes solicited opinions about unusual photos from the "Press Room Imaging Team."

As Voyager 2 approached Saturn, images were constantly coming down to Earth and being displayed on these television monitors. The images would change every few seconds to make way for the next shot. Knowing that not all photos could be released to the press or public simply because of their large numbers, I set up a camera on a tripod to take photos of the screens in case something interesting flashed by.

One such photo was a close-up of the rings near a small gap. It was immediately apparent that something bizarre was being seen since it appeared that some sort of wake was evident in the rings near the gap. It was such a weird shot that I even moved the camera in for a closer view, and did not capture the entire frame with all the image information, as I normally did. So, I snapped the shot, expecting to hear about this phenomenon the next day at the press briefing. Nothing was said and no one had any answers for my questions.

My expectation was that there was either an unseen moon causing this wake pattern or some localized phenomenon where the rings were actually dragging on one another. My speculation remained just that for several years. I kept expecting to hear of a find of a new moon located directly in the rings, but nothing happened.

In January 1984 I decided to take matters into my own hands to see if I could solve the mystery. I wrote to JPL and explained the situation, while trying to track down the exact photo number for confirmation. There was a gap of 26 photos where this mystery photo might be within the images sent from Voyager 2. I did not receive a reply for over a year, so in March 1985 I called my JPL contact. Later that month, I received a reply.

The gist of the reply was that the wave pattern I saw on the image was simply an artifact of the television set itself. This is called a moire pattern. However, I had enough knowledge of electronics and televisions that I did not believe that this was the case. The pattern followed the curve of the rings and was not horizontal or vertical with respect to the television screen. I believed then, and I believe today, that the pattern Voyager photographed was real.

In September 1990, an 18th moon of Saturn was discovered and credited to Mark Showalter at NASA's Ames Research Center. The moon was eventually named Pan. According to the Associated Press article about the discovery, Showalter found the moon by using a computer program to search Voyager raw images for shots "leaving a 'moonlet wake' pattern, similar to the disturbance a boat causes by moving through water." The moon was located in a gap in the rings known as Encke's Gap and was never directly imaged until the Cassini mission to Saturn arrived in 2004.

I sent a letter of congratulations to Showalter, asking if he could tell me what Voyager frames had been used for the discovery, but never received a reply.

Since Cassini has found other unusual patterns in the ring system of Saturn, I have recently decided to reopen the case with JPL to try and locate the original raw image, somewhere between frame numbers 1414S2-001 and 1440S2-001. So far, JPL has not been forthcoming with the data.

Michelle Evans

President, Mach 25 Media

March 24, 2005

Boat Wake

Detail view showing the wave pattern discussed in the narrative to the left.

Note the decreasing nature of the pattern, similar to the way a wake forms after the passage of a boat through the water. Also note how it is not related to the television screen itself, but follows the curve of the rings.

The black dots verify the vertical orientation of the image and the horizontal bars are the scan pattern of the television screen giving the horizontal reference.

Photo taken off the television screen at JPL showing image 1414S2-001. This photo then gives the lower number in which to bracket the wave pattern photo, for which I do not have an exact image number.

Full frame of the photograph showing the wake pattern.

In all of the photos I took off of television screens at JPL over the years of planetary encounters by Voyager, there is not one single photo that shows a pattern even remotely similar to the one taken in this photo, thus my belief that it is not a moire pattern or other artifact caused by the television set.

To the left of the wake pattern, other rings can be easily seen. The dark band that crosses at approximately a 45 degree angle in the lower left corner is a scan bar caused by the television set and the exposure by my camera.

Image 1440S2-001. This photo then gives the higher number in which to bracket the wave pattern photo. Somewhere in those 26 images is the one showing the pattern that would either verify my theory or disprove it.

Correspondence concerning the ring wake pattern.

The Associated Press article from September 1990 announcing the discovery of a moon embedded in the rings of Saturn.