NASA sounding rockets chase hurricane-like winds from the edge of space
After nearly a week of weather delays, a NASA rocket team has successfully launched the first of two pairs of suborbital sounding rockets from the heights of the Norwegian Arctic. The Vorticity Experiment (VortEX) finally launched after 10 p.m. local time tonight on a $10 million mission to study how atmospheric disturbances generate high-velocity winds at the edge of Earth’s tenuous atmosphere. Earth.
The main scientific drivers are to better understand the atmospheric “fluid” just above 100 km and how strong winds and wave action mix it, Gerald Lehmacher, professor of physics at Clemson University in South Carolina and Principal Investigator for VortEx, via email. We hope the results of our experiment will improve our ability to model and predict conditions in the upper atmosphere, he says.
The Alomar Observatory, run by the Andøya Space Center in Andenes, Norway, has the ground-based radar and imaging systems needed to detect buoyancy waves that occur in real time, according to NASA. Norway’s Scandinavian mountains are a regular source of buoyancy waves as winds rush against the mountains and rise into the sky, according to NASA.
What are buoyancy waves?
Disturbances in air density, pressure, wind, temperature that propagate horizontally and vertically, says Lehmacher. Buoyancy (as denser air sinks and lighter air rises) is the force that causes air to oscillate in a vertical direction, he says. Depending on their size (wavelength), their period varies between 10 minutes and several hours, explains Lehmacher, who notes that these waves are like acoustic waves, but slower and therefore subject to upward and downward movements.
Even so, buoyancy waves and the winds they generate at altitudes of 80-140 km are believed to drive much of the global weather patterns of our planet. But until now, researchers have struggled to get real-time in situ data at such high altitudes.
To this end, VortEx will use radar, sounding rockets and optical instruments to map an area of the Earth’s mesosphere approximately 100 by 200 km.
One of the two rockets in each pair will eject 16 vials containing the chemiluminescent tracer trimethylaluminum (TMA). These luminescent clouds can in turn be tracked from the ground. The team is specifically looking for giant hurricane-like eddies in our upper atmosphere, NASA says. These eddies, or vortices, may be key to higher atmospheric weather patterns that affect the entire globe, according to NASA.
The other rocket will make continuous measurements of plasma temperature and density, notes the Andøya Space Center.
As of this writing, however, the launch of the second pair of rockets remains uncertain, due to weather conditions.
From a scientific point of view, there should be at least a 2-3 hour interval between bursts to launch in different atmospheric conditions, Lehmacher explains.
As for how these buoyancy waves will actually be detected?
When these waves pass over our launch area, we can see them as ripples moving across a pond, Lehmacher explains. A special ground-based infrared camera will observe the movements of the atmosphere nearly 87 km away, he says, where hydroxide (OH) molecules emit bright, temperature-modulated infrared emissions.
As for data analysis?
Data analysis will begin right after launch, says Lehmacher. Once the atmospheric parameters have been calculated from all the different experiments, we will turn to modeling the local atmosphere with the aim of reconstructing the entire wind field, he says. We have detailed measurement inputs out to 100 km, but rocket (and some radar) measurements above 100 km are still very rare, he notes.
Computer models of the team’s launch data should help fill in some research gaps.
The process is similar to weather forecasting, Lehmacher says. The more information you have to initialize the model, the better the predictions, he says.
“The laws of atmospheric physics are well known, but we will collect more wind data in this region than in any previous experiment,” says Lehmacher.