The University of Central Florida (UCF) – which manages the Arecibo Observatory in Puerto Rico on behalf of the U.S. National Science Foundation (NSF) – announced on August 26, 2019, that it has received a big NASA grant to observe and characterize near-Earth objects (NEOs) that pose a potential hazard to Earth or that could be candidates for future space missions. Total for the four-year grant: $19 million.
That’s a big investment in Arecibo, which has been using radar to analyze NEOs for some years now, since the mid-90s observing some 60 to 120 objects per year. Yet this observatory has had funding concerns in recent years, which are now, for the immediate future, solved. In a statement, UCF commented that the team of asteroid hunters at Arecibo expects:
… to gain a lot of knowledge about asteroids.
And that’s all to the good, as most will agree. In recent decades, astronomers have fully realized the potential of asteroids to strike our modern-day Earth and cause perhaps disastrous harm. More about that below. Congress made NEOs a priority when it directed NASA in 2005 to seek out and characterize at least 90 percent of near-Earth objects larger than 140 meters (459 feet) by the year 2020. This new grant – a four-year, $19M award – comes on the heels of a 4-year, 12.3M grant, announced earlier this month, for emergency supplemental funds for upgrades and repairs to the big Arecibo radio dish and surrounding site, needed especially in recent years as multiple hurricanes have swept across the Caribbean, including Hurricanes Irma and Maria in 2017.
The combination of the two grants puts Arecibo on very strong footing, for now.
It’s interesting in part because Arecibo was the world’s largest single-aperture telescope from its completion in 1963 until July 2016 … but no more. That honor now goes to China’s Five hundred meter Aperture Spherical Telescope (FAST). Prior to FAST, Arecibo was described as uniquely powerful at finding and analyzing NEOs. That may still be true, and it’s certainly the case that the big dish at Arecibo – built into a natural depression in the landscape of this Caribbean island – is a powerful tool for professional research not just in radar studies of NEOs but also for radio astronomy and atmospheric studies.
UCF said in a statement:
The observatory is home to the most powerful and most sensitive planetary radar system in the world, which means it is also a unique tool available to analyze NEOs, such as asteroids and comets. The knowledge helps NASA determine which objects pose significant risks and when and what to do to mitigate them. NASA officials can also use the information to determine which objects are the most viable for science missions – landing on an asteroid is not equally easy for all of them. Information the observatory provided about asteroid Bennu, for example, is one of the factors that led NASA to select the OSIRIS-REx mission for funding.
The award also includes money to support STEM education among high school students in Puerto Rico, [bringing] together 30 local high-school students per semester once a week for 16 classes to learn about science and research at the observatory.
The S-band planetary radar system … at Arecibo Observatory is the most sensitive planetary radar system in the world. This is why Arecibo is such an amazing tool for our work. Our radar astrometry and characterization are critical for identifying objects that are truly hazardous to Earth and for the planning of mitigation efforts. We can use our system to constrain the size, shape, mass, spin state, composition, binarity, trajectory, and gravitational and surface environments of NEOs and this will help NASA to determine potential targets for future missions.
Astronomers have come to realize NEOs’ potential for harm. When I started writing about astronomy in the 1970s, some astronomers scoffed at the notion that our modern-day Earth might be struck by an asteroid. Of course, scientists knew Earth had been struck many times in the past. Although most meteor craters on Earth have been worn away by wind and weather, large meteor craters do still pockmark Earth’s surface in some places, for example, Meteor Crater near Winslow, Arizona. These craters are visible signs that large asteroids can and did bombard our planet, but those bombardments were, for the most part, relegated solely to the distant past by most astronomers until relatively recently.
Several things changed to alter that view. For one thing, an event in living memory – the Tunguska event of 1908, which had taken place in a remote part of Siberia and remained mysterious for many years – came to be widely accepted as likely being caused by a small comet or stony asteroid. More importantly, technology changed, improving to the point where astronomers could discover vastly more asteroids than before. A few thousand asteroids were known and named in the 1970s. Now hundreds of thousands of asteroids are known, and, indeed, some have orbits that bring them near Earth. These are the near-Earth objects (NEOs) that NASA wants to hunt down and track with Arecibo, and, ultimately, to visit.
The NEOs are a blessing and a curse. They contain raw materials that humanity may someday be able to mine. But, although astronomers do know for certain that no large world-destroying asteroid is on a collision course with Earth for the foreseeable future, we are less certain about the smaller asteroids, the ones that could, say, destroy a city. In recent years, astronomers have begun to speak of Earth in the cosmic shooting gallery. The Earth is the target in this way of looking at things, and asteroids are the bullets.
Small asteroids sweep near Earth all the time. It’s not unusual for a small asteroid to sweep closer to us than the moon. Scientists estimate that several dozen asteroids in the 6– to 12-meter (20- to 39-feet) size range fly by Earth at a distance closer than the moon every year. Only a fraction of these are detected.
NASA wants to detect more of those close-passing asteroids. It wants to learn to travel to asteroids and mitigate the potential for a collision. That’s why it just awarded this large grant to Arecibo. Good luck, asteroid hunters!
Bottom line: Arecibo Observatory has just received a 4-year, $19 million grant from NASA to find and study near-Earth objects (NEOs).