Preliminary summary of the results of the MEIDEX experiment on the Columbia ferry * Executive summary, prepared by Dr. Yoav Yair, project coordinator on behalf of the MEIDEX team
Tel Aviv University's MEIDEX experiment was carried out on Columbia Space Shuttle Flight 107 between 16.1.03 and 30.1.03 (last observation), at the end of four and a half years of meticulous preparations and planning. The preparation for the experiment included a team of scientists at the Scientific Control Center in Greenbelt POCC, Maryland (Goddard Space Flight Center), the deployment of a team of researchers and a research plane to Heraklion Airport in Crete, and a forecasting team at the Open University in Tel Aviv. These three centers worked in close coordination throughout the days of the mission, often in real time and with continuous mutual updates on the development of the mission, weather conditions and other operational issues, including the transmission of early results from observations and measurements analyzed during the mission itself. The research teams were joined by a second circle of colleagues from many countries around the world, who performed supporting measurements of various types during the 16 days of the mission. The MEIDEX experiment thus became a complex and special international operation, which gained special interest in the scientific community.
All space and air test systems functioned flawlessly. Apart from minor telemetry issues that were addressed by the engineers during the mission, the MEIDEX cameras and recording systems worked perfectly. The data was recorded within the experimental system, as an additional backup also in the crew cabin on the shuttle, and most of it was transmitted in real time to the ground as a third backup and for quick analysis (Quick-Look results). The work with the late Col. Ilan Ramon and his Columbia team members was smooth, fast and yielded many scientific fruits.
During the 16-day mission of the shuttle Columbia on its flight STS-107, observations of desert dust from space were planned to be made in two areas of interest, the Mediterranean Sea and the equatorial Atlantic Ocean near the coast of West Africa. To the observations in the Mediterranean region were added aerial measurements from a trained research aircraft that went on sorties from the island of Crete, at a time determined each day according to the time of the ferry's passage in the area and according to weather conditions. The purpose of using the research plane was to provide data on the vertical structure of the dust storms for the purposes of calibrating the measurements from space. MEIDEX's execution method included an early prediction of the movement of dust plumes from the Sahara north to the Mediterranean Sea (and west to the Atlantic) based on an analysis of synoptic maps and a model for forecasting dust storms developed by us, and the delivery of a daily briefing to the astronauts (Execute Package) with emphasis on observation as well as required changes in the camera angle or tilting the entire shuttle. Based on the spatial geometry of the location of the shuttle's expected trajectory relative to the predicted location of the plume and the location of the research aircraft, and to the extent that the distance was greater than the camera's coverage capacity at maximum axis tilt (which is limited to 22 degrees), the POCC team asked planners in Houston for shuttle tilt changes (Roll-bias). In most cases we answered yes and the ferry was maneuvered to the best observation position.
In the first week of the mission, no dust storms occurred in the Mediterranean and most of it was covered by clouds. The research flights at that time focused on the movement of particles from Europe (mainly air pollution) south to the Mediterranean Sea. In the second week of the mission, large storms occurred in the Atlantic Ocean and the astronauts photographed and recorded 9 tracks where dust plumes were clearly visible coming from West Africa. These data are of very high quality and will be used for cross-checking and verification against NASA's TERRA and AQUA satellites. The worsening of the weather in Greece and the recommendation of the forecasting team required the flight crew to move to Israel, which was carried out quickly. In two research flights conducted immediately after the team returned to Israel from Tel Aviv to the west, the plane measured dust plumes in their movement from Egypt. Both measurements were conducted in coordination with the passage of the shuttle and recorded by the astronauts. In this way, the original goal of the experiment was achieved - simultaneous measurement of dust from an airplane and the space shuttle.
Of the 77 minutes of video where the crew definitely reported seeing desert dust, 51 minutes (66%) were transmitted to the ground and recorded. The permit is lost. All measurements from the 22 hours of flight of the research plane are saved and analyzed.
A secondary MEIDEX experiment was performed during the night hours of the orbit, and included measurements of electrical phenomena in the upper atmosphere above the tops of lightning storm clouds (Sprites and Elves). The observations were conducted with the same methodology of dust observations, that is, daily meteorological forecasts and updating the astronaut team on the location of the storms. Most of the observation routes were in the South Indian Ocean, Australia, the Fiji Islands and the South Pacific Ocean (were also conducted over Africa, Brazil and the USA). Real-time targeting of the shuttle was performed by the POCC team based on satellite imagery and lightning detection systems operating in the same areas. The crew members who operated the MEIDEX cameras "hunted" the lightning storms based on the lightning flashes they saw with their eyes. This part of the experiment was more successful than expected and documented many cases of "elves" and "fairies" at heights of 60 to 100 km above the ground, in different parts of the world. At the same time as the observations from the shuttle, a lot of electromagnetic information was collected at stations in Israel and around the world (USA, Hungary, Japan, Antarctica), which will allow cross-referencing and investigation of the lightning storms that created the "elves". It can be stated with a high degree of confidence that the scientific objective of this secondary experiment was fully achieved. During the mission, the photographs were distributed to the research partners in the countries of the world and aroused great enthusiasm, since the quality of the scientific information and the work that is being done in calibrated measurement above the atmosphere have a unique potential for understanding what is happening at these heights of the atmosphere.
Out of more than 9 hours of data recorded in night orbits during shuttle lightning storms, we have close to 7 hours of video (77%).
As part of the experimental method, calibrations were performed for the Xybion camera in order to monitor its performance and to assess the accuracy of the measurements. The calibrations were performed on targets whose optical properties are known in advance: the moon, and the Libyan desert region. Out of six lunar calibrations performed in flight, we have data from 2 calibrations, and they will be analyzed as part of the processing of the results. Initial evaluation taught about stability in camera performance.
On the 13th day of the flight, the MEIDEX system made a casual observation of a forest fire in Brazil, requested by NASA scientists. This is an experiment of an initiated fire in collaboration with the Brazilian government, designed to test the effect of the smoke from those forest fires on the cloudiness and climate in the Amazon region. The resulting photograph showed an interesting and special interaction of the plumes of smoke with the clouds, where the smoke seems to suppress and reduce the formation of clouds in the area. This casual measurement that was not planned in advance produced an excellent result that caused great excitement among climate researchers.
During the mission, the team recorded many hours of video in cloud-covered areas and in clean areas without the presence of desert dust. Some of that data is in our hands, and will be used for future studies on sea surface reflectivity and the morphology of cloud fields. It is difficult to estimate the amount of video of this type of information, because the recordings are now in the hands of the NASA investigation committee. The recordings will arrive in Israel in the coming weeks and will then be thoroughly examined by university researchers.
