The MISU Middle Atmosphere Group

MAGIC A Study on "Stardust"

You probably have seen shooting stars in the night sky. But have you ever wondered what happens to all this material "burning up" in the atmosphere...? The MAGIC project has been designed to study this great mystery of the Earth's upper atmosphere. The acronym "MAGIC" stands for the aims of this project: Mesospheric Aerosol - Genesis, Interaction and Composition.

In January 2005, space scientists and space engineers have come together at Esrange, Sweden to conduct the campaign. The MAGIC rocket was launched on January 10, 2005. It took scientific instruments to a height of 95 km. The launch salvo consisted of 2 balloons, 3 meteorological rockets and the major MAGIC rocket. Launch conditions were good with low auroral activity and clear sky for the lidar measurements.

The major aim of the MAGIC campaign was to collect the meteoric material in the atmosphere and to return it to the ground. After the flight, the samples have been taken to various laboratories where techniques like electron microscopy are applied to analyze the collected "stardust".

Follow the MAGIC Campaign with the Campaign Photo Diary !

Meteoroids, Smoke and Magic Dust...

In fact, about between 10 and 100 tons of meteoric material enter the Earth's atmosphere every day. Most of it comes in the form of small meteoroid particles with sizes smaller than 1 mm. These particles come with typical speeds of 10-20 km/s. Collisions with air molecules heat the particles to temperatures high enough to vaporise them. This happens at heights between 70 and 100 km, in a part of the atmosphere that is known as the mesosphere. During this evaporation process larger particles can glow so brightly that they become visible from the ground as shooting stars.

Meteroid particles consist mainly of metals like iron, silicon, potassium, sodium and various oxides. Thus, the evaporated material forms metal layers in the upper mesosphere. These layers are well known and can be observed with ground-based instruments like lidars. However, when it comes to the further fate of this material, we simply do not know very much...

There are some ideas based on theoretical considerations: It is generally assumed that the metallic material condenses within a few days to form tiny particles with a radius of only a few nanometers (1 nanometer = 1 millionth millimeter). These recondensed particles are commonly called smoke particles. They are assumed to follow the general motion (advection) of the air. Sooner or later this motion can transport the smoke particles down to the lower atmosphere where they can be taken up by clouds and finally rain out of the atmosphere.

It has also been suggested that these smoke particles play an important role for many atmospheric processes. As an example, they could provide condensation nuclei for the growth of ice particles that form noctilucent clouds in the mesosphere. Noctilucent clouds are by far the highest clouds that we know about the atmosphere. They occur at heights around 82 km, but only during summer and only at high latitudes. During summer twilight conditions they can become visible as bright structures in the night sky. The photo below shows an example: Noctilucent clouds observed above Stockholm. (Photo by N. Wilhelm)

Other atmospheric processes that smoke particles may be involved in concern chemistry, charging processes and the metal budget in the mesosphere. So smoke particles are potentially very important in the atmosphere.

But:  Noboby has ever investigated these smoke particles. As a matter of fact, nobody has ever proven that these particles really exist.

Because of this lack of knowledge, smoke particles have been called, less seriously, for "magic dust". This is where the idea for the MAGIC rocket project started. We want to find out wether these particles exist in the mesosphere. And we want to study their properties.

Our Scientific Questions

• Do smoke particles of cosmic origin exist in the mesosphere?
• How many particles are there as a function of height?
• What is the size of these particles?
• What are they made of?
• How are they charged?
• How are these particles transported in the atmosphere?

The MAGIC Project

In order to study smoke particles in the mesosphere, we address several related parameters simultaneously: smoke particle distribution and properties, atmospheric structure, transport processes, and charge distribution. The MAGIC campaign has taken place at Esrange, Sweden, in January 2005. It has provided co-ordinated atmospheric measurements from rockets, balloon, the ground as well as from the Swedish Odin satellite. (Photo of Esrange by J. Gumbel)

The MAGIC project is an outstanding example for international collaboration in atmospheric research. The MAGIC idea was developed at the Naval Research Laboratory (NRL) in Washington DC, USA. This was done in close collaboration between U.S., Swedish, and German scientists. In early 2002, NASA approved and funded the development of the MAGIC instrumentation. At the same time the Department of Meteorology at Stockholm University (MISU) proposed a Swedish rocket campaign to launch the MAGIC instruments from Esrange. In 2003, the Swedish National Space Board (SNSB) approved and funded this campaign.

The table below shows the research groups involved in the MAGIC campaign and its analysis. Click here if you want to contact individual MAGIC scientists.

Payload preparations and launch operations at Esrange are carried out by the Swedish Space Corporation (SSC).

The picture above shows tests of the MAGIC rocket payload at Packforsk in Stockholm. (Photo by J. Gumbel)

Particle sampling

The collection of meteoric smoke particles in the mesosphere is based on the newly developed MAGIC detectors. The collection of nanometer-size particles is difficult. They are so small that they simply tend to follow the airflow around the payload rather than reaching instrument surfaces. Therefore, aerodynamic considerations were of critical importance when designing the MAGIC experiment. The basic idea is to make the detection surface small enough to make aerodynamic influences negligible: The MAGIC sampling surfaces have a diameter of less than 3 mm and are positioned on long pins. These pins are extended one by one from the MAGIC detector box. Three of these boxes have been flown on the MAGIC payload, each containing 8 pins. The entire instrument with an extended pin can be seen to the right. (Photo by T. Waldemarsson)

This detection concept has been tested by extensive aerodynamic simulations. The diameter of the pins is of the same order as the mean free path that an air molecule travels in the mesosphere between collisions with other molecules. Under these conditions shock fronts disappear and smoke particles can approach the collection surface undisturbed.

The impact of smoke particles onto the probe surfaces could be tested experimentally by using a cluster beam facility at the University of Jena in Germany.

The MAGIC payload with the collected particles has returned to the ground on a parachute. After recovery, the MAGIC probes are transferred to the laboratories involved in the analysis. Transmission Electron Microscopy (TEM) is the major tool for investigating the smoke particles. It serves to determine the number of the particles and their sizes. By combining TEM with x-ray spectroscopy techniques the composition of the particles can be determined. These measurements will be carried out at the Naval Research Laboratory (NRL).

Additional investigations by gamma ray spectrometry and highly sensitive mass spectrometry will be carried out at the Instituto Nazionale di Fisica Nucleare in Italy.

The charge properties of the meteoric particles have been studied by the charged particle detectors from the Laboratory for Atmospheric and Space Physics at the University of Colorado directly during the MAGIC rocket flight.

Measuring Water, Temperature, Winds, . . .

It is of central importance to investigate how the atmospheric circulation transports meteoric smoke. To this end, we relate the particle distribution to detailed measurements of water vapour. Water vapour serves as an excellent tracer for mesospheric transport. These measurements have been done using MISU's optical hygrometer technique. We have applied this technique earlier both on rockets and balloons, e.g. during the Hygrosonde-2 campaign from Esrange.

These measurements have been complemented by ground-based measurements (lidar and radar) and meteorological rockets to provide information about the background state of the atmosphere, in particular temperature, density and wind. Additional ground-based measurements on Esrange have concerned ionospheric and auroral conditions.

The picture to the left shows the laser beam of the Bonn University lidar that is located at Esrange. The light that the atmosphere scatters back from this laser beam provides us with information about atmospheric density and temperature. (Photo by J. Hedin)

Radar measurements by ESRAD and EISCAT provide information about ionospheric structures. An example for such structures are Polar Mesosphere Winter Echoes that are studied by the Institute for Space Physics in Kiruna. These echoes are possibly connected to the presence of smoke particles.

Modelling Studies

In support of the MAGIC project, also a number of modeling studies will be performed. These studies concern all phases of meteoric particle evolution from ablation of meteorites to the global transport of smoke in the mesosphere. Institutes involved in these studies are MISU, the Naval Research Laboratory and the University of East Anglia. The University of East Anglia is also heavily involved in laboratory studies related to smoke particles.

MAGIC and the Odin Satellite

The MAGIC campaign is closely related to another Swedish space project: the Odin satellite. The launch of the MAGIC rocket from Esrange was coordinated with an overpass of Odin. With its unique capabilities to measure water vapour and temperature in the mesosphere, Odin is a perfect complement to the aims of MAGIC. The same idea was applied during the Hygrosonde-2 campaign in 2001, when valuable conclusions could be drawn from combining the large scale Odin data with local rocket and balloon measurements.

As a matter of fact, Odin is connected to the scientific questions of MAGIC in many ways. A major objective of Odin in the mesosphere is the detailed study of noctilucent clouds that are thought to depend on the presence of smoke particles as condensation nuclei. Odin also performs optical measurements of several metals that are the product of meteor ablation in the mesosphere. The figure below shows an example: The points represent Odin measurements of the column density of sodium atoms over the Northern Hemisphere in April 2003.

The Future

Further applications of the MAGIC experiments are already being planned. The MAGIC experiment is a light-weight, self- contained instrument that can readily be incorporated into a variety of different rocket payloads In March 2005, a rocket from NASA's launch site at Wallops Island will carry a MAGIC detector. This will provide valuable mid-latitude data complementary to the Esrange flight.

Important future measurements of meteoric smoke will concern the summer mesosphere at high latitudes such as Esrange. Summer is the time for noctilucent clouds. Of course, it would be extremely interesting to launch rockets with MAGIC detectors and other instruments into these clouds. Remember that meteoric smoke particles are thought to be necessary as condensation nuclei for noctilucent clouds.

Other MAGIC applications concern meteoric smoke measurements at lower latitudes. Here possible influences of the particles on mesospheric chemistry are expected to be largest. Measurement of atomic oxygen and other reactive species would be a natural complement for such chemical studies.

Further Reading

about meteoric material in the atmosphere:

• Ceplecha et al., Meteor phenomena and bodies, Space Sci. Rev., 84, 327-471, 1998.
• Love and Brownlee, A direct measurement of the terrestrial mass accretion rate of cosmic dust, Science, 262, 550- 553, 1993.
• Hunten et al., Smoke and dust particles of meteoric origin in the mesosphere and thermosphere, J. Atm. Sci., 37, 1342-1357, 1980.
• McNeil et al., Differential ablation of cosmic dust and implications for the relative abundances of atmospheric metals, J. Geophys. Res., 103, 10899-10911, 1998.
• Thomas, Mesospheric clouds and the physics of the mesopause region, Rev. Geophys., 29, 553-575, 1991.
• Plane, The role of sodium bicarbonate in the nucleation of noctilucent clouds, Ann. Geophys., 18, 807-814, 2000.
• Summers and Siskind, Surface recombination of O and H2 on meteoric dust as a source of mesospheric water vapor, Geophys. Res. Lett., 26, 1837-1840, 1999.

about MISU's rocket experiments:

• Khaplanov et al., Hygrosonde - A direct measurement of water vapour in the stratosphere and mesosphere, Geophys. Res. Lett., 23, 1645, 1996.
• Gumbel et al., Scattering phase functions and particle sizes in noctilucent clouds, Geophys. Res. Lett., 28, 1415-1418, 2001.
• Gumbel et al., Odd oxygen measurements during the NLC-93 rocket campaign, J. Geophys. Res., 103, 23399-23414, 1998.
• Gumbel, Aerodynamic influences on atmospheric in situ measurements from sounding rockets, J. Geophys. Res., 106, 10553-10563, 2001.
• Horányi et al., Simulation of rocket-borne particle measurements in the mesosphere, Geophys. Res. Lett., 26, 1537-1540, 1999.

More Information

If you are interested in further information about the MAGIC project, contact Jörg Gumbel (gumbel @ misu.su.se). Click here if you want to contact individual MAGIC scientists.

Impressions from the campaign are available online from the Campaign Photo Diary. Stay tuned and check this website for results of the campaign!