Oil is that precious substance which, for better or worse, we have quite an addiction to. We spend billions of dollars and risk (and occasionally sacrifice) lives to retrieve it from Earth’s depths. Yet, Earth is often not so greedy. The planet regularly releases crude oil on its own, with no help from us. The extent to which oil “seeps” up on its own is not known. However, scientists have recently uncovered a new tool to help them understand this phenomenon.
Two NASA satellites, Terra and Aqua, are each outfitted with a device called a Moderate Resolution Imaging Spectroradiometer (MODIS). NASA regularly orders the MODIS instruments to collect images from across the Earth’s surface as part of the primary missions of these satellites. Usually, these images are cataloged and stored, free to all. However, a research team interested in studying harmful “red tide” blooms of algae in the Gulf of Mexico stumbled upon a new use for these images: tracking the Earth’s natural release of oil.
The research team includes scientists from the University of South Florida, the National Oceanic and Atmospheric Administration, and the University of Massachusetts-Dartmouth. They used images from the Gulf of Mexico taken over almost ten consecutive years, and were able to track the frequency and extent of natural oil seeps from the ocean floor. MODIS images were particularly useful due to the effect oil has on the surface of water. Oil makes water look smoother. Thus, on a clear day, if MODIS images were taken at just the right angle to cause a bright reflection of sunlight on the ocean surface, researchers could see evidence of released oil in the form of black “streaks” across the ocean. The streaks had to be at least several hundred feet across to be picked up by MODIS.
Researchers have previously used satellites to monitor oil spills. However, those satellite projects have often involved the costly rerouting of a satellite to a particular area, and relied on expensive instruments on the satellite to take measurements. MODIS, however, is already operating on two satellites that regularly take large numbers of images across the globe, and is much cheaper to operate. Given clear skies and a reflective ocean surface, this research team has shown that MODIS can easily pick up and track natural oil seeps over time. In addition, governments and interest groups could use time-lapsed images from the same area to follow manmade oil spills, including spills of unknown origin. The devastating oil spill in the Gulf of Mexico has renewed interest in tracking oil slicks. Thus, interest groups will no doubt begin to put these image databases to good use.
What these new findings don’t explain, however, is how and why Earth naturally seeps oil. It is unlikely that the planet periodically releases what we covet — black gold — just to taunt us. Then again, I was always told that God has a sense of humor. Perhaps a dark one.
MODIS Image of the Gulf of Mexico, with natural oil seeps, provided courtesy of the NASA Earth Observatory. This image was taken well before the Deepwater Horizon oil rig exploded and sank, causing oil to gush from the uncapped well.