A team of TAU scientists is gearing up for the first space flight of an Israeli astronaut, slated for the year 2,000. The astronaut, TAU graduate Col. Ilan Ramon, will be performing a TAU-led experiment to measure the composition of aerosols (dust particles suspended in the air) over the Mediterranean region and their affect on cloud formation, rain, and changing atmospheric conditions. The Project will also help assess the reality and extent of global warming, and might have wide implications for "atmospheric correction" of remote sensing measurements from space.

Ramon is an F-16 pilot in the Israel Air Force and an alumnus of TAU in mechanical engineering. He and colleague Col. Yitzhak Mayo are presently undergoing intensive training at NASA headquarters in Houston, Texas. Concurrently, a large ground and airborne team is being set up by the TAU researchers.

The Project - called MEIDEX (Mediterranean Israeli Dust Experiment) - is part of a cooperation agreement between NASA and the Israel Space Agency (ISA), and is headed by TAU Professors Zev Levin, Joachine Joseph and Yuri Makler, all of the Department of Geophysics and Planetary Sciences at the Raymond and Beverly Sackler Faculty of Exact Sciences. Geographically, the Middle East is at the crossroads of the world's largest deserts and at the boundary of wet and dry climate regions. The greatest source of dust in the world lies in the desert stretching from the Maghreb in Northern Africa to India.

A dust storm over the Dead Sea

The experiment will involve taking measurements of dust storms over the Mediterranean using remote sensing from satellites in space, which will be compared with simultaneous measurements taken from aircraft flown into dust storms over the sea, and ground stations to be situated either in the Negev or on the Israeli coastline. The aircraft will be manned by researchers from the Cloud and Precipitation Group of TAU's Department of Geophysics and Planetary Sciences, led by Prof. Levin, and will take measurements of the size distribution of dust particles and samples for chemical analysis. The TAU space set-up, to be monitored by Col. Ramon during Columbia's orbit, comprises two NASA-approved radiometric CCD multispectral cameras with UV and infrared capabilities.

The TAU findings will help NASA confirm measurements of dust storms taken from the TOMS (Total Ozone Measuring Spectrometer) space satellite, and from MODIS (Moderate Resolution Imaging Spectral Radiometer), to be launched in a year's time. "The TAU device will complement both TOMS and MODIS resulting in improved data," says Prof. Levin. "The TOMS satellite detects aerosols over both land and sea but only above one or two kilometers altitude and only if they absorb UV light. The MODIS sensors are designed specifically to penetrate the lowest layer. The TAU set-up combines the technological capabilities of both satellites and in addition will provide calibration for the space measurements."

TAU and NASA scientists at NASA headquarters, together with TAU Prof. Yoram Shapira, Minister-Counselor for Science and Technology at the Embassy of Israel in Washington DC (back row, left); and astronauts Ilan Ramon and Yitzhak Mayo (front row, fourth and fifth from left).

Scientists are interested in aerosols because they may counter the "greenhouse effect" and global warming. Aerosols affect the climate in two broad ways: firstly, they alter the radiative properties of the atmosphere by scattering radiation - both incoming solar radiation and that which is reflected back up from the earth's surface. Secondly, aerosols play a critical role in the cloud formation process, serving as a sort of "seed" for attracting condensation, resulting in greater quantities of rain. Both these effects act in contrast to those of greenhouse gases, which absorb the radiation and heat the atmosphere. Research carried out at TAU has shown that on their way to the eastern Mediterranean from Northern Africa, some dust particles become coated with soluble substances such as sulfate from industrial air pollution. When these enter clouds they appear to enhance the formation of rain. On the other hand, industrial air pollution without the presence of large dust particles reduces rain formation.

The space shuttle can remain in space for a maximum of 16 days. The most suitable months for carrying out research on the movement of desert dust from North Africa are March-April or October-November, the seasons when there is the greatest probability for dust storms. Since most of the storms which occur in the Mediterranean never reach Israel, the TAU team will be flying over Sicily and from there to the place where the storm develops. Another aim of the Project is to supply data on the modification of dust as it is transported over the sea. These data will help improve visibility models for the Israel air force and will assist in improving images taken from space over the region.