54 | SCIENCE ILLUSTRATEDPilots Jim Payne and Tim Gardner in
the record-setting Perlan II glider.up-current when the polar jet-stream
and the polar vortex merge. Enevoldsen
discovered that these waves can reach as
high as 39km into the atmosphere – which
is more than twice as high as had been
previously believed. In 2006, Enevoldsen
and plane enthusiast Steve Fossett made
plane history, beating the altitude record by
gliding through the air a dizzying 15,544m
above the Andes Mountains in Argentina,
aboard the Perlan I glider.Glider records weather and ozone
With wind speeds of 400km/h in the strato-
sphere, flying is rather risky; those powerful
mountain waves could force planes into
quick dives and hazardous spins. That orig-
inal Perlan I mission ended with the pilots
activating an emergency parachute.
On the other hand, planes have more to
offer than weather balloons or satellites,
which have been scientists’ primary meas-
uring equipment in the stratosphere since
the 1970s. Weather balloons are unmanned
and difficult to control, while satellites can’t
map variations in the stratosphere up close,
as planes can.
Manned jet planes have flown even
deeper into space than Perlan II, but their
high speeds and major emissions of petrol
fumes make it almost impossible to make
accurate measurements in the stratosphere.However, scientists can use Perlan II for
controlled exploration by means of sensors
on the glider which can measure pressure,
air moisture and temperature.
For many years, meteorologists believed
that weather was produced only in the
troposphere, the air layer from Earth’s
surface to the stratosphere at an altitude of
15km. Today, we know that what happens in
the stratosphere spreads downwards.
In the stratosphere, the polar vortex (a
vortex of westerlies) blows in a circle around
the polar region above Canada, Siberia, and
Scandinavia. This vortex supports the jet
streams that blow at lower altitudes. On the
other hand, the polar vortex can also be
influenced by Rossby waves from the tropo-
sphere. These waves are produced by the
Earth’s rotation and the difference between
terrestrial and ocean regions. The waves rise
and can break down the polar vortex, weak-
ening the jet streams in the troposphere
and leaving room for warm air to blow far
north, while cold air blows far south.
Perlan II’s research of wind, tempera-
tures and chemistry in the stratosphere can
teach scientists about these phenomena. In
explaining key elements that contribute to
producing the weather on Earth, this know-
ledge may be vital for long-term weather
forecasts. This is particularly true in North-
ern and Western Europe, where the linkbetween stratosphere and troposphere
seems to be particularly strong.
Apart from teaching us more about the
weather, the record-breaking glider will also
measure ozone in the stratosphere. The data
will be used to research the holes in the
ozone layer produced by decades of green-
house gas emissions that split ozone
molecules on contact. Some of the major
culprits were used in refrigerators up until
1987, when nations throughout the world
agreed to phase out the gases from such
common use. Perlan II will document to
what extent the ozone layer is healing itself.Next stop Mars
Perlan II glides in places where the air is 97%
thinner than normal, and where tempera-
tures reach as low as -70 degrees Celsius.
Similar atmospheric conditions exist on
Mars, where the oxygen-poor atmosphere
will make it impossible to use combustion
engines. Perlan II has shown that we can
glide across long distances under the right
conditions. Long distance transport will be
vital if we wish to explore Mars and settle in
several areas of the planet.
Back on Earth, Perlan II will continue its
research of the highest air layers. Next year,
Jim Payne and Tim Gardner will try to beat
their own altitude record and reach 27km,
surfing on the wild mountain waves.AIR
BUS
TECHNOLOGY GLIDERS