The same GPS signals that you rely on to navigate rush hours, find a restaurant, or track your kids can also be used to predict when hurricanes are forming in tropical waters. At least, it is the hope of a few who have developed a fleet of six small satellites to take off Monday from Cape Canaveral on a SpaceX Falcon heavy rocket. The mission is also the last stage of a conflict between government-sponsored meteorological data collection systems and private systems, which many observers hope will lead to better forecasts at lower cost.
Known as the Constellation Observation System for Meteorology, the Ionosphere and Climate (or COSMIC-2), the mission takes advantage of a strange property of GPS radio signals: they bend and slow down slightly then that they travel in the atmosphere. This bending does not affect the precision of the ground navigation; it is visible only sideways by something else in orbit. It's a bit like that when you dip a pencil into a glass of water half full and the image refracts slightly through the denser liquid (physicists know it well) Snell's law).
The denser the atmosphere, the more GPS radio waves become distorted. Eleven scientists get this information on density, they can determine atmospheric humidity, pressure and temperature at intervals of one kilometer. Getting this type of granular information about what is happening in the atmosphere is essential to make weather forecasting models more accurate.
"It's a very elegant technique," says Bill Schreiner, director of the COSMIC program at the University Corporation for Atmospheric Research in Boulder, Colorado, one of the mission's sponsors, alongside the National Oceanic and Atmospheric Administration, Air Force, and National Taiwan Space Organization. "It's a precise way to measure the atmosphere, but it's also reproducible."
Schreiner compares the radio concealment, as it is called, to the launch of 5,000 additional weather balloons each day, which is the number of additional measurements that the six COSMIC-2 satellites will be able to collect. The radio occultation system will also collect more information about the equatorial oceans, the hurricane spawning grounds and the typhoons that are plundering the world's coasts. The other advantage is that it can collect information on atmospheric conditions in remote areas of the globe that ships and meteorological stations can not reach. The COSMIC-2 satellite is also equipped with a sensor that measures the speed at which solar particles are moving, information that will help space weather scientists know when a solar flare or significant solar flare could occur.
Compared to other meteorological satellites, COSMIC-2 represents a good deal at a cost of $ 250 million, half of which was paid by Taiwan, according to Schreiner. "It's a cheaper order of magnitude," he says. In comparison, NOAA's four GOES geostationary meteorological satellites, the first of which was launched in 2016, cost taxpayers $ 11 billion. had a few hiccups in the space since then.
Daryl Kleist, a physics scientist at NOAA's Environmental Modeling Center, says the new COSMIC-2 satellites will be used to calibrate GOES measurements and improve long-term climate models. COSMIC satellite data will also help forecasters better track and predict the movement of great atmospheric rivers, the fast air that governs much of the weather in North America.
"We expect that we will have better forecasts of such events because of the direct benefits of the COSMIC-2 mission," Kleist said during a conference call.
With the launch of next week, radio occultation satellites will transition from a pilot program to mature technology. The first set of COSMIC satellites, launched in 2006, made it possible to test it. The solar energy batteries of all the first six satellites except one are exhausted and no longer produce measurements. The new COSMIC-2 mission is expected to last at least five years, it is said. At the same time, rising costs have forced NOAA and its Taiwanese partners to cancel an additional set of radio-occulting satellites orbiting the poles planned for launch in 2021. NOAA is considering instead buy more meteorological datasome of them were obtained by blocking the radio by commercial satellite companies.
The first commercial purchases in 2017, however, went badly and scientists at NOAA and UCAR were not satisfied with the quality or quantity of data produced. Last year, NOAA officials selected two companies for a second-round test, and the agency is still evaluating whether the weather is lenient enough to buy, according to UCAR officials. It has not yet been used for weather forecasts.
Compared to private satellites, COSMIC-2 satellites are larger (about three cubic feet versus 2.5 cubic inches) and heavier (618 pounds versus 11 pounds). They last longer (5 years vs. 2 years), have a larger antenna and can collect more information about the Earth's atmosphere. COSMIC-2 also contains an advanced instrument designed by NASA's Jet Propulsion Laboratory, capable of collecting atmospheric information closer to the Earth's surface, a layer up to six thousand meters high called the troposphere, where most of the clouds And water vapor exist. The ability to collect more precise measurements, as well as to know the conditions at different levels of the atmosphere, represents a clear improvement over previous meteorological satellites.
Of course, building and launching private cubes is less expensive. For the moment, some NOAA officials seem to want to privatize meteorological data collection data at the same time as they are building a federally funded radio concealment network. The NOAA administrator would normally be decisive, but the appointment by President Trump of Barry Myers, former CEO of the private weather forecast company AccuWeather, has been blocked by the Senate since 2017.
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