Can NASA Satellites Monitor Radiation Plumes from the Fukushima Disaster?

NASA is using multiple satellites and sensors to monitor the aftermath of the devastating earthquake and tsunami that rattled Japan on March 11.

However, NASA’s Earth-observing satellites are unable to directly measure radiation-containing plumes, such as those experts fear may have wafted from a damaged Japanese nuclear plant in Fukushima prefecture.

We checked in with Robert Cahalan, the head of Goddard Space Flight Center’s Climate and Radiation Branch and the project scientist for the SORCE satellite, to find out why. Here’s how Cahalan explained it:

“NASA could fly a drone directly into a cloud to detect radioactivity, but it’s not easy to measure the damaging radiation from the Fukushima plant with a satellite. 

The radiation consists mostly of negatively charged electrons from so-called “beta decay” of radioactive products of the nuclear fission reactions, as well as positively charged alpha particles, which are identical to a helium nucleus (for example, two protons and two neutrons all bound together into a single particle). 

NASA does have detectors in space that measure such charged particles, but the great majority of these particles don’t come from Earth. Rather, they come from the sun, which emits a very large number of charged particles in what is called the “solar wind” — which is especially intense when the sun is active. The particles can also come from sources outside our solar system, so-called galactic cosmic rays, or GCRs, that become more detectable when the sun is less active.

Fortunately, we humans down on Earth are protected from a lot of this particle radiation by Earth’s magnetic field, which steers charged particles along the field lines toward Earth’s magnetic poles, and thus acts as a shield for the human population. 

Trying to pick out the Fukushima radioactivity from the huge number of charged particles in outer space would be like finding the proverbial “needle in the haystack.” So, unfortunately, we have to rely on ground-based particle detectors, like the common Geiger counters that have been shown in use by the workers in their white hazmat suits in the tragic scenes in Japan.

There is also high-energy gamma radiation, which is electromagnetic radiation. Again, NASA has had the Compton Gamma Ray Observatory (GRO) in space, and now has FERMI. But these look for extremely intense bursts of gamma radiation that come from colliding galaxies, quasars, and other extreme events in the universe. The low flux of gamma radiation from the nuclear power plant is all absorbed in the Earth’s atmosphere, and never makes it into space. The only way we might detect some gamma radiation from Earth’s surface would be if we created a gamma ray burst by detonating a large nuclear bomb. That kind of event cannot happen in a nuclear reactor, even in the worst case of a core meltdown.

NASA’s Earth-observing satellites monitor many health related quantities including aerosols and ozone, nitrous oxides, and other constituents in the air we breathe, as well as fires, floods, and other events that impact life on Earth; however, near-Earth radioactivity can only be detected near the radioactive source, not by satellites.”

Visualization of solar wind and Earth’s magnetosphere courtesy of Steele Hill and NASA’s SOHO team. Visit this page for more information.

–Adam Voiland, NASA’s Earth Science News Team

Behind the Scenes With Scientists Who Created A Global Air Pollution Map

Yesterday, NASA posted an article about a new global map of health-sapping PM2.5 air pollution. The Dalhousie University researchers who made the map used data from NASA’s MISR and MODIS satellite instruments, as well as information from a computer model called GEOS-Chem. You can read the news story here (or the accounts from Wired, Public Radio, and UPI), but we also wanted to share some of the audio from our interview with the scientists for those who want more details. The scientists being interviewed are Aaron van Donkelaar and Randall Martin; the person asking the question is Goddard-based science writer Adam Voiland.

What was the most interesting thing you found from this analysis?  

Why go to the trouble of making this map?

What’s the heavy band of particulate matter in Africa? Is dust bad for our health?

Martin: There’s no lower bound on health effects

Have other researchers done this kind of analysis?

Are these data ready for prime time?

How did you combine data from both satellite instruments?

–Adam Voiland, NASA’s Earth Science News Team