The ER-2 is a high altitude plane used by NASA to help study various subjects in the upper levels of the Earth’s atmosphere. The ER-2, known as the Earth Resources High Altitude Airplane, is being used in an air quality study over Hawaii to help improve air quality forecasts for Hawaii and beyond. Sensors that’ll eventually be added to space satellites are being tested on the ER-2 to help identify pollutants in the air as part of this study over the Rainbow State.
As Dr. Michael Mercury, a systems engineer from the Navy’s Jet Propulsion Laboratory, described the very expensive and technologically advanced equipment put on the ER-2. As much as they could plan the ER-2 missions, with exact flight paths at a specific time of day, one thing the could not count on was the Hawaii weather. “The ER-2 is a high altitude airplane. It is not designed to fly at 35,000 feet like a commercial jet. It’s operating, cruising altitude is 65,000 feet, where 98% of the atmosphere is below it. Sure, it needs to get to that point, so it flies through the altitudes that other airplanes fly at. But, we generally avoid flying through severe turbulence to get to it’s cruising altitude,” said Dr. Mercury.
Turbulence on an airplane is generally caused by wind shear, which is caused by winds changing speed or direction at different levels of the atmosphere. Many are familiar with the normal turbulence that a commercial jet can handle, but normal turbulence has a more dramatic effect on the ER-2 than it does on a commercial jet. “The run of the mill turbulence that a commercial jet can fly through is generally avoided by our team controlling the ER-2. That plane is designed for a much different type of environment that a commercial aircraft is. We have confidence that our pilots can get the ER-2 through the turbulence but it is a safety risk and they prefer a much smoother path to 65,000 feet.”
To try to get an idea on the turbulence that will be experienced by the ER-2 getting to 65,000 feet, Dr. Mercury and the rest of his team talks to meteorologist at the Marine Corpse Base Hawaii before and during the mission. “On the day of the mission, we are in contact with meteorologists right to the point the pilots settle in at 65,000 feet. We examine the NAM and GFS weather models to get an idea on what type of conditions our pilots can expect. And to, nudge, nudge, wink, wink, double check what the meteorologists are telling us.” Dr. Mercury said with a broad smile on his face.
Another problem that members of the ER-2 mission try to avoid as much as possible are clouds. Dr. Mercury explained, “Even with all of our equipment, clouds present a problem. First off, they often cause turbulence. Secondly, they make the sulfur dioxide plumes and particulate matter that we are looking for more difficult to differentiate, both from each other and from the rest of the atmosphere. We can generally ‘see’ through most types of clouds to determine the electromagnetic footprints we are looking for, but generally we are less confident in the data gathered when the spectrometers have to ‘look’ down at and through the clouds. Also, there are certain types of clouds that when present, such as large cumulus clouds loaded with moisture, are next to impossible to get data that we can confidently use.”
The problem with clouds are not limited to just the ER-2. “Clouds will still be a problem even from space,” Dr. Mercury said, adding that the clouds are an issue for the spectrometers on either the satellite or the ER-2.
Data and insights from the ER-2 mission in Hawaii will help fine-tune the equipment and software that’ll be used on the satellite when it’s eventually sent to space to study the atmosphere.