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This is part of a study of the upper level jet stream located in the mesosphere.

These five rockets will release an aluminum based chemical into the upper layers of atmosphere (the mesosphere) that will form milky-white clouds that will trace winds in space. These clouds might be visible for public up to 20 minutes by East coast residents from southern parts of New Hampshire and Vermont till South Carolina.

The launch window for March 15, 2012 is scheduled between midnight and 1:30 a.m. EDT. The backup launch days are March 16 through April 3. For more information, refer to the NASA Wallops page at http://www.nasa.gov/centers/wallops/news/12-03.html.

The map of the mid-Atlantic region of the U.S. shows the projected area where the rockets may be visible while the motors are burning through flight.

The map of the mid-Atlantic region of the U.S. shows the projected area where the rockets may be visible while the motors are burning through flight. It also shows the flight profile of each of the five rockets. Credit: NASA/Wallops

Why studying the mesosphere is so important?

The mesosphere is a layer of Earth's atmosphere. The mesosphere starts at 60 km above Earth's surface and goes up to 100 km high. Image credit: Windows to Universe

The mesosphere is the layer of the Earth’s atmosphere that is directly above the stratosphere and directly below the thermosphere. It is located above stratosphere and below thermosphere occupying a layer from 60 km to 220 km above Earth’s surface. ~ 40 tons of meteors typically enter the mesosphere per year. Most of them dissipate giving away iron and other material, which creates a refractory layer there.

This region is also known for having strong zonal East-West winds which fly with speeds up to 500 km/h. The high-altitude winds in the mesosphere were first discovered in 1960s. Current studies confirm their connection to the complicated electrical current patterns that surround Earth, but it needs a further investigation.

The other atmospheric phenomena such as tides, gravity waves and planetary waves are also present in this region. Most of these tides and waves are actually excited closer to Earth – in the troposphere and lower stratosphere, but they propagate upward to the mesosphere. In the mesosphere, their amplitudes grow so large that waves become unstable and dissipate, which in turn deposits kinematic energy (momentum) into the mesosphere and, according to one theory, this creates high winds and largely drives global atmospheric circulation.

In order to figure out what drives these high winds and how atmospheric disturbances in one hemisphere could influence weather in the other, scientists must get an understanding of how these winds move and what kind of turbulence they show.
One possible kind of turbulence which could be found in these winds is so- called 3D turbulence. If you imagine water which is flowing down a rocky river and swirling with small ripples around rocks or gusting winds on Earth moving falling leafs around, that is 3D turbulence.

The theory suggests that the upper level jet streams are moving following laws implied by 3D turbulence, and therefore they can be modeled similar to small-scale waves in water. Such waves in the mesosphere might arise due to heat in the lover atmosphere that varies in the course of a day.
On the other hand, studies show that the winds at that altitude are flying way too fast to fit with the small-scale wave’s model.

“This area shows winds much larger than expected,” says Miguel Larsen, a space scientist at Clemson University, who is the principal investigator for the Anomalous Transport Rocket Experiment (ATREX).

Moreover, if the small-scale wave’s model were correct, the man-made tracers and satellites’ debris, which happen to enter the mesosphere (e.g. Space Shuttle debris) should have broke up and dissipate due to high turbulence, but they did not.

So to get a better view of what is going on in the upper layers of Earth’s atmosphere, NASA designed the ATREX experiment. It will help us understand “the big question about what is driving these fast winds” said Miguel Larsen.

Challenges

Because the mesosphere is located lower than the Earth’s low orbit where it can be studied using satellites, but still higher than where most planes fly, it is difficult to probe.

However, this location makes it a perfect target for the sounding rocket experiment. A sounding rocket, which is also called a research rocket, is a rocket that carries scientific instruments and designed specifically to perform experiments during its sub-orbital flight, which usually takes between 5 and 20 minutes. The instruments the rocket carries use this time to take measurements and to send data back to Earth.

For more information, see References for the NASA sounding rocket report, 2011.

The ATREX experiment

The ATREX experiment comprises 5 sounding rockets, which will launch at once from Wallops NASA center. They will follow specific timing and direction to gather the required data.

These rockets are scheduled to launch on one clear night between March 14 and April 3. The clear night skies are also required at three camera sites located along the coast in Virginia, North Carolina and New Jersey.

The launch date is set for March 15 is between midnight and 1:30 a.m. EDT. The backup launch days are March 16 through April 3.

The red dots over the water show where ATREX will deploy chemical tracers to watch how super fast winds move some 60 miles up in the atmosphere. While there are only five rockets, two will deploy two sets of tracers, resulting in seven clouds. Only six dots appear in this image, since two will be deployed at the left-most red/green dot, which represents Wallops. Three cameras will track the cloud tracers – one at Wallops and two located at the green dots. Credit: NASA/Goddard Space Flight Center

The rockets will through a substance to create clouds in the lover mesosphere which could be traceable from the Earth. Scientists will then use special cameras to track the five clouds and measure how fast and in which directions they move away from each other.

This task is quite difficult though, because it requires 3D mapping of several spots in high atmosphere (100 km high) in only 20 minutes.

The chemical used to create clouds is called trimethyl aluminum (TMA). When dispersed, it forms milky, white clouds which can be traceable from the ground. So we could see them on East coast. These clouds will follow the winds in space and scientists will be able to track them with cameras. In addition, two of the rockets will have instrumented payloads to measure pressure and temperature in the atmosphere.

How to watch it

The map of the mid-Atlantic region of the U.S. shows the projected area where the rockets may be visible while the motors are burning through flight.

The map of the mid-Atlantic region of the U.S. shows the projected area where the rockets may be visible while the motors are burning through flight. It also shows the flight profile of each of the five rockets. Credit: NASA/Wallops

According to NASA, these clouds may be visible for up to 20 minutes by residents from South Carolina to southern New Hampshire and Vermont.

The NASA Visitor Center on Wallops island, VA will be open at 10 p.m. on March 14, 2012 for public viewing. Launch status also is available on the Facility’s Facebook page and its launch status line at 757-824-2050.

The mission will be web cast beginning at 10 p.m. on March 14, 2012 at:
http://sites.wff.nasa.gov/webcast

Mission status on March 14 can be followed on Twitter at:
http://www.Twitter.com/NASA_Wallops

More information on the ATREX mission is available on the Internet at the ATREX experiment page -
http://www.nasa.gov/mission_pages/sunearth/missions/atrex.html

References:

NASA Sounding Rockets Annual report 2011, http://sites.wff.nasa.gov/code810/files/Sounding_Rockets_Annual_Report_2011.pdf
ResearchBlogging.org
Larsen, M. F., and C. G. Fesen (2009). Accuracy issues of the existing thermospheric wind models: Can we rely on them in seeking solutions to wind-driven problems? Ann. Geophys., 27, 2277–2284, doi:www.ann-geophys.net/27/2277/2009/, 2009.

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