Conveners: Lyle Broadfoot, Ian McDade
Thursday, June 17, 03:25-05:30 PM
Engineering Center
The Arizona Airglow experiments (GLO) have served the purpose of their primary sponsor and are now available for general use. It has become clear through previous shuttle flight activity that the experiment is very productive and needs a larger science team and a well-defined mission to take advantage of the GLO data product. A new plan is being developed for continued use of the GLO instruments in a supporting role to ground based observers.
A group of Canadian aeronomers have agreed to join a US team to present the GLOs to NASA and the Canadian Space Agency as an international program. The proposal will be to continue flight on the Shuttle in a campaign mode in a collaboration with ground based observers. The follow-on plan is to deploy the GLO on the International Space Station (ISS). The Shuttle flights will give an opportunity to examine the effectiveness of the overflight data in complementing ground based programs. These studies would be used to define the most effective use of the GLO facility when it is deployed on the ISS.
The ISS orbit is inclined at 51º to the equator, with a precession of about 70 days. This is a good orbit for many aeronomical observations. From the ISS/Shuttle altitude the limb tangent height of 100 km is depressed about 18º from the horizontal. This means that useful collaborative observations can be made with ground stations up to 69º latitude, well inside the auroral zone for half of the day. This will allow overflight of most of the airglow, lidar and radar ground stations.
The ALOHA/ ANLC-93 campaigns observed signatures of dynamic changes in the nightglow, and the spectacular gravity wave event described by Taylor et al. (1995) appears to be consistent with the sharp changes recorded often in GLO data. Taylor observed a transition in OH Meinel emission exhibiting a 50% jump in intensity in less than 4 minutes. The progress of the intensity pulse across the nightglow scene was estimated at 76 ms-1. This pulse occurred in about 18 kilometers of lateral distance, not unlike the scale suggested by GLO observations. Notable wind shear in the persistent sodium layer near 90 km was reported during the ALOHA-93 campaign (Gardner et al., 1995). These dynamic changes suggest that the only way to complement the data from a ground site is to operate in "snapshot mode" to stop the action. All of the relevant data must be acquired in a single overhead pass of the spacecraft, and for now, only the Shuttle is sufficient to the task because of the high data rate available to its instrumentation. Although there would be only one pass over each optical ground station per night, the nightglow layer could be characterized by GLO above many ground sites. Complementary Shuttle orbits on either side of the ground site would supplement the integrated picture.
The workshop will be an open forum to discuss the possibilities of a campaign approach and to pole community interest in this project.