By Shellie-Anne Espinosa
21st Space Wing Public Affairs
PETERSON AIR FORCE BASE, Colo. — In the hopes that they can discover a way to measure the water content of snow and develop a satellite to obtain a global picture, NASA is basing their SnowEx mission at Peterson Air Force Base, Colorado, during the month of February to test new instrumentation.
“SnowEx is a multiyear NASA project to figure out how best to remotely sense snow from space,” said Edward Kim, SnowEx lead project scientist with NASA’s Goddard Flight Center.
Kim explained snow is critical to society in four key ways — water resources, natural hazards, water security and weather information.
“About a sixth of the world’s population depends on water coming from snow,” said Kim. “The western U.S., itself, is pretty dry. There, anywhere from 70, 80 and some places 90 percent of the water comes from snow.”
As a natural hazard, Kim said snow is responsible for the nine most devastating U.S. floods in the 20th century, either because the snow melted too quickly or the ground was frozen and caused the snow melt to run off.
Water security affects the global water situation. Getting a satellite up that can read snow on a global picture is important to NASA. They want to get the most accurate information possible to key decision makers around the world.
“Because so much of your water comes from snow,” Kim said, “it’s important to know who has snow and how much, so that you can figure out what’s going to happen in the world.”
The ultimate goal of SnowEx is to gain enough information to create this satellite to get a picture of snow water around the globe.
“Snow water is extremely difficult to measure from space,” said Kim. “We’ve been trying to do it for many decades.”
Currently, satellite capability is limited to measuring snow cover and precipitation as it falls. There are no single sensors that measure snow water. Kim said snow just varies too much from one point to another. So NASA, in a collaboration with Naval Research Laboratory, U.S. Forest Service, USDA Natural Resources Conservation Services, and various other groups, began a campaign involving ten different sensors on five different aircraft and an extensive ground crew to find the right combination of instruments to measure snow water.
“NASA is a space agency,” said Kim. “We figure out how to put satellites together and get them into space. Snow is one of the gaps. It’s just that it’s a very difficult problem. It’s taken us a long time, but using a number of sensors, getting them out there so that we can compare them and having that ground truth will help us figure out what’s the right combination of sensors to put on a future snow satellite.”
The five year program kicked off in 2017 to study forested areas in western Colorado, particularly Grand Mesa and Senator Beck Basin. Partnering with other agencies allows NASA to use a ground team of around a hundred people to measure snow water content at various points to create what they are calling “ground truth.” This information will be used to compare readings from the different sensors being tested on the aircraft to see what works and what does not.
The ground crews are dealing with harsh weather conditions requiring them to work above 10,000 feet in windy and freezing conditions. They are studying in remote locations that often require snow shoes, skis and snowmobiles to get to reach.
“Snow varies a lot,” Kim said, explaining the benefit of a satellite over multiple ground crews. “If I can measure how much snow is here and I walk over there, it’s going to be different. That variability is part of what makes it difficult. Even though we have hundreds of snow measurement sites around the U.S., the U.S. is big. To do the equivalent to what a satellite could do, you would need thousands or tens of thousands of stations, and that’s just not feasible.”
NASA ultimately chose Peterson AFB as its hub of operations for this portion of SnowEx due to the size of aircraft involved and the study locations.
“Peterson was the natural choice,” Kim said. “It’s close enough to our sites, so we don’t have to spend a lot of time going back and forth. It’s near major cities. If we need supplies and equipment, it’s easy to get. It’s got the right facilities, like the runway and fuels. It’s just the right place.”
The aircraft chosen to fly out of Peterson AFB is the P-3 Orion loaned to NASA from the Naval Research Laboratory, along with a flight crew from Scientific Development Squadron ONE (VXS-1) out of Naval Air Station Patuxent River, Maryland. The plane is large enough to carry five of the ten different sensors being tested during SnowEx. It is also able to fly for long durations allowing multiple flyovers for each instrument to do its readings.
“Each sensor has its optimum way that it likes to observe the snow,” Kim said. “So we have to fly over the mesa multiple times. One time for one sensor, a second time optimized for the next sensor, and so forth. You add up how much flight time that is, you need an airplane that can fly for a lot of hours.”
Kim said the plane is able to meet the needs for the different types of observations. Along with being large enough to carry the instruments and having the ability to fly long missions, the P-3 also allows for the crew to fly low to the ground, at around 1,000 to 1,500 feet, to allow for one of the sensors to operate properly.
Over all, Kim feels that the mission is running smoothly so far.
“Everything is going great, especially the ground truth,” Kim said. “I was just out there over the weekend. All the measurements are going well.”
SnowEx will continue its mission at Peterson AFB throughout the month of February. All the data acquired will be stored at the National Snow and Ice Data Center in Boulder, Colorado, and available to anyone who may have need of the information.