Langley Payload Aboard Balloon

One Experiment Will Test Accuracy Of CERES Data

By JULIA COLE
SAIC

A Langley Research Center payload is scheduled to launch this month aboard a high-altitude balloon for a planned flight around the world. The balloon will reach an altitude above nearly 99 percent of the Earth’s atmosphere.

NASA’s Ultra-Long Duration Balloon will lift off from Alice Springs, Australia, carrying its main payload called Nightglow. One of Langley’s two experiments that are piggybacking on the Nightglow flight will measure the Earth’s energy balance from a vantage point that could transform how scientists study climate.

Four times a day, the balloon’s path will cross an area of the Earth observed by Langley’s Clouds and Earth’s Radiant Energy System (CERES) instruments onboard NASA’s Terra and Aqua satellites.
Scientists will use observations from Langley’s Balloon-borne Radiation Experiment to test the accuracy of measurements from CERES.

“The Earth’s climate system is driven by the distribution of incoming energy from the Sun and the outgoing energy escaping to space,” said Wenying Su, lead scientist for the experiment and a Hampton University research professor working with Atmospheric Sciences’ researchers at Langley.

Measurements of the Earth’s energy budget such as those from CERES and the high-altitude balloon experiment “provide the necessary information to develop and test our ability to predict long-term climate change,” Su said.

The balloon, designed for flights up to 100 days, will fly at an altitude of about 22 miles (35 kilometers). Traveling west across the Indian Ocean, it will carry Langley’s payload of three commercial radiometers to measure energy radiated and reflected by the Earth. The main goal of the experiment is to validate CERES’ measurements, but Su hopes a successful flight will open a new avenue for studying the radiation balance.

“This is the first time an Ultra-Long Duration Balloon has been used for Earth-science research,” she said. “In the future, we hope to have a balloon designed just for Earth-science studies, but first, we have to see how well this flight works.”

In the past, technological limitations prevented scientists from using balloons for extensive studies of the radiation balance. The Ultra-Long Duration Balloon’s ability to maintain a near-constant altitude and remain aloft for long periods of time now makes it an ideal platform. The cost of a balloon mission is also much less than for a satellite project.

“The biggest advantage of using a balloon is that we can measure the outgoing radiative flux directly at the balloon’s altitude, instead of retrieving it indirectly from a satellite,” Su said.

The Ultra-Long Duration Balloon will travel about one percent as fast as a satellite at a stable altitude, allowing for observations not attainable from a satellite’s orbit. The balloon’s radiometers, for example, will be able to measure how the planet’s reflected sunlight and emitted energy change during the course of a day. A 100-day or longer flight would also enable scientists to study seasonal changes in the Earth’s radiation budget.

With additional technological advances, a constellation of high-altitude, long-duration balloons could offer an alternative to satellite missions.

“A constellation of balloons would be able to monitor dynamic changes to the Earth’s radiation budget over the entire globe,” Su said. “This would provide unprecedented data to study short time scale phenomena related to climate science.”

A second Langley payload, called the Global Positioning System/Solar Reflection Experiment, or GPS/SREx, will also piggyback on the Nightglow flight. On its fourth balloon mission, the GPS/SREx instrument will help validate computer models that predict high-altitude reflection characteristics of the land and ocean for GPS instruments.

The GPS/SREx mission, a project in the Airborne Systems Competency, has applications for global hydrology, oceanography, aircraft safety and national defense.

NASA’s Earth Science Enterprise sponsors the CERES Mission, managed by Langley. The Wallops Flight Facility of Goddard Space Flight Center manages NASA’s Scientific Balloon Program.

For more information on the CERES balloon experiment, visit http://snowdog.larc.nasa.gov/uldb on the Internet.

Julia Cole works for SAIC in support of Langley’s Atmospheric Sciences Competency.



Wenying Su, lead scientist for Langley’s Balloon-borne Radiation Experiment, holds a radiometer similar to the three which will fly aboard NASA’s Ultra-Long Duration Balloon and measure energy radiated and reflected by the Earth. “This is the first time an Ultra-Long Duration Balloon has been used for Earth-science research,” Su said. “In the future, we hope to have a balloon designed just for Earth-science studies, but first we have to see how well this flight works.”

Photo by Jeff Caplan