Proposed Ground Observations of Noctilucent Clouds by Students and Amateur Scientists

Forrest M. Mims III

NASA's upcoming Aeronomy of Ice in the Mesosphere (AIM) satellite experiment (Fig. 1) was the focus of a science teachers workshop held at the University of Alaska at Anchorage from 23 to 29 July. The AIM satellite experiment, which is scheduled for launch in early 2007, will provide important opportunities for ground observations of noctilucent clouds (NLC) by students, teachers and amateur scientists. That's because the AIM mission is specifically designed to investigate noctilucent clouds (NLCs) that occur at the edge of space at an altitude of around 82 to 85 km (50 miles).

Ground observations and photographs of NLCs during AIM overpasses could have scientific value. However, NLC observational opportunities are limited, for these rare clouds are visible only during summer and generally only between about 50 to 70 degrees north or south of the Equator. NLCs, which are completely unrelated to the aurora, appear as silvery white or bluish clouds in the twilight glow long after sunset or well before sunrise when the sun is at least six degrees below the horizon.

Figure 1. This illustrations shows how the AIM satellite will measure the profile of gases and aerosols in the upper atmosphere by observing the rising and setting sun during each orbit. AIM Education and Public Outreach.

The AIM teachers workshop was planned and organized by Dr. Dianne Robinson, a science professor and Chair of the Interdisciplinary Science Center at Hampton University. She was assisted by Barbara Maggi, Dr. Paul Adams, Paul Jones, Matt Rogers and others, all of whose roles are described here.

Thirty teachers were selected to attend the workshop. The competition was tight, for some 1,000 teachers applied.

The highlight of the workshop was the science presentations by the AIM mission principle investigators, Drs. James M. Russell III and Scott Bailey, and by an astronaut and amateur astronomer who has made numerous photographs of NLCs from Earth orbit, Dr. Donald R. Pettit. The side conversations between between Drs. Russell and Bailey with astronaut Pettit (as in Fig. 2) were absolutely fascinating, for they provided a rare opportunity to listen in as scientists who have planned and are about to execute an unmanned space mission to investigate NLCs exchanged ideas with an astronaut who may have seen and photographed more NLCs from space than anyone.

Figure 2. Dr. Donald R. Pettit (center) makes a point as only an astronaut can while discussing his observations of noctilucent clouds from the International Space Station with AIM principle Investigators Drs. James M. Russell III (right) and Scott Bailey (left). Note that astronaut Pettit transformed his laptop computer into a foottop unit for this discussion. Photograph by Forest M. Mims III.

The Noctilucent Cloud Field Trip

My main assignments for the AIM workshop were to teach digital photography basics and recommend an economical digital camera to be provided to the participants. I approached the latter assignment with trepidation, for I had never observed an NLC prior to the workshop, even though I lived in Alaska for four years as a young boy. A key objective for the workshop was to determine if the camera I recommended, the five-megapixel Panasonic Lumix DMZ LZ2, could capture an NLC display. The camera has a 6X optical zoom, which is ideal for capturing details of an NLC display. But reviews of the camera noted that images made during darkened conditions are noisy. Would this camera be able to capture an NLC display? Would we even see an NLC display?

The weather forecast for the entire week of the workshop was for overcast skies, so it appeared that there would not be an opportunity to look for NLCs, much less evaluate the ability of the cameras to photograph them. As the week progressed, there was a glimmer of hope in the forecast. Then, on the fourth day of the workshop, there was a dramatic change in the weather during an all-day field trip to Seward. The sky was nearly clear the entire day, and conditions appeared good for trying to observe NLCs after sunset.

Our tired group arrived back at the Anchorage train station around 10:30 PM, and sunset was at 10:50 PM. After a brief break at the dorms, around 20 of us reassembled for a trip to Flat Top Mountain to watch for any NLCs that might make an appearance. We arrived at the observation area on Flat Top after midnight and began scanning the twilight glow for anything unusual. Cirrus clouds formed dark blobs within the orange twilight glow, but nothing else was to be seen.

After 1:00 AM, I noticed some unusual spots just above the brightest part of the twilight glow between two peaks. The subtle spots were slightly paler than the orange glow over the horizon. I've observed and photographed twilight glows for many years and have often seen dark bands and spots in the twilight glow caused by clouds, smoke and dust. But I've never seen pale regions in the twilight glow.

I alerted some of the participants to this phenomenon, including Barbara Maggi of Hampton University, one of the organizers of the workshop. Minutes later, Barbara made the announcement we were all waiting for. She spotted faint but obvious NLCs at the eastern side of the twilight glow. We all trained our cameras on the NLCs and began taking dozens of photographs using a wide range of speed and ISO settings.

As we watched and took photos, the NLCs became more pronounced. Soon, the more prominently visible NLCs formed a band of braided, white clouds across a third of the twilight glow. Off to the west a fainter NLC display was also visible.

Our group used more than a dozen Lumix cameras and a variety of other cameras to photograph the NLC display. While the display was not nearly as pronounced as those others have seen and photographed, we were delighted by our first opportunity to see NLCs. Thanks to the displays on all the cameras, we could immediately tell that the cameras were indeed capturing the NLCs.

Many of the workshop teachers managed to photograph the NLC display. Among the most unusual photos was one by Wayne R. Gilchrest, Teacher of Marine & Environmental Science at the Chesapeake Bay Governor's School in Bowling Green, Virginia. When Wayne noticed the NLC display brightening somewhat as he and others were leaving the site, they stopped their car and Wayne broke all the tripod rules I taught in class and successfully acquired a handheld 1/2-second handheld photograph.

A review of some of NLC imagery we acquired is given in "Noctilucent Cloud Observation Report" in this installment of The Citizen Scientist.

The author received a consulting fee and travel reimbursement for participation in the AIM workshop. This article was not solicited by the AIM program or any of its participants and was prepared for The Citizen Scientist under the auspices of the Society for Amateur Scientists.