Many of the threats humanity faces come from ourselves. If we were to list them we would include tribalism, greed, and the fact that we are evolved primates and that our brains have much in common with animal brains. Our animal brain exposes us to many of the same destructive emotions and impulses that animals experience. We wage war and get caught up in generational conflicts. There are genocides, pogroms, doomed shiploads of migrants and horrific mashups of all three.
Isn’t humanity having fun?
But not all threats we face are as persistent as our internal ones. Some threats are external and we can use our technologies and knowledge of nature to fight them. Case in point: asteroids.
NASA can’t do much about our own destructive impulses, but they are definitely able to protect us from dangerous asteroids and comets. These objects are called Near-Earth Objects or NEOs. In 2005, the US Congress passed the NASA Authorization Act of 2005.
Under its requirements, it obliges NASA to step up their game when it comes to detecting NEOs. It states in part that NASA “… should recognize, track, catalog and characterize the physical properties of near-earth objects with a size of 140 meters or more …” In addition, NASA instructs NASA to carry out a surveying program that “… 90 Percent “will achieve completion of its catalog of near-earth objects (based on statistically predicted populations of near-earth objects) within 15 years of the coming into force of this law.”
NASA has made progress in this area and has so far found around 40% of objects 40 meters or more in size. And they get a new tool that they can use to fill out their survey. Called the NEO Surveyor, it is an infrared space telescope designed to find, track, and characterize NEOs. The University of Arizona will lead this new mission, led by Amy Mainzer. Mainzer is an expert in infrared astronomy and a professor at the Lunar and Planetary Laboratory at the University of Arizona.
“Even asteroids as dark as a piece of coal cannot hide from our infrared eyes.”
Professor Amy Mainzer, University of Arizona.
NASA only approved the preliminary design phase at this point, so many details could change between now and the spacecraft’s planned deployment in 2026. But here’s what we know so far.
The spacecraft will carry out its survey in the infrared. Earth-based telescopes have found most of the NEOs cataloged to date, but finding the rest in visible light is extremely difficult. According to a press release, this would take decades. Finding them in the infrared will be much more efficient, but that cannot be done from Earth. A spaceship is needed for this.
Infrared observation is vital to the mission as NEOs happen as they approach the inner solar system. They are heated by the sun, and the NEO Surveyor will detect this heat. Even the blackest, least reflective asteroids are visible in the infrared. In a press release, Mainzer said: “Asteroids and comets approaching Earth are heated by the sun and give off heat that the NEO Surveyor mission can absorb. Even asteroids as dark as a piece of coal cannot hide from our infrared eyes. “
Artistic illustration of the NEO Surveyor, a space telescope used to track down and catalog NEOs. Image source: NASA / JPL
The artist’s illustration above gives us an idea of how NEOs will appear to the NEO Surveyor. Their faint heat signatures appear as strips of dots, which are shown in red in this image for simplicity. Therefore, they are different from the background stars, which are coded blue in this picture. Hunting for NEOs in the infrared will also allow scientists to determine not only the position and trajectory of the objects, but also their size. And it’s their size that determines how devastating they could be if they hit Earth.
“Impact energy is highly dependent on the size of a single asteroid, so NEO Surveyor’s infrared observations will greatly expand our ability to predict the behavior of some of Earth’s neighbors who might be on a trajectory to pay us a surprise visit.” says Mainzer said.
The NEO Surveyor will build on the success of the Near-Earth Object Wide-Field Infrared Sensor (NEOWISE). NEOWISE was a predecessor of the NEO Surveyor. It was a four-month mission extension to the WISE mission conducted when the mission ran out of coolant. Professor Mainzer is the lead scientist at NEOWISE.
This graphic shows asteroids and comets observed by NASA’s Near-Earth Object Wide-field Survey Explorer (NEOWISE) mission. Photo credit: NASA / JPL-Caltech / UCLA / JHU
The University of Arizona will handle all mission management, including the design and construction of the infrared detectors themselves. The university will also oversee the mission and manage the investigations and overall operations of the team. The U of A has a successful track record in this regard, including its participation in the OSIRIS-REx mission and its management of the HiRISE (High-Resolution Imaging Science Experiment) camera on the Mars Reconnaissance Orbiter (MRO).
“The university’s leadership in infrared astronomy and asteroid research makes it uniquely suited to lead this next-generation infrared sky survey,” said Elizabeth “Betsy” Cantwell, senior vice president of research and innovation at the University of Arizona.
Professor Mainzer and her team will supply eight infrared detectors for the space probe’s camera. Each of the eight offers a resolution of 4 megapixels. That is enough resolution for the NEO Surveyor to recognize the tiny infrared light spots from NEOs. As part of their job, they test various infrared detector assemblies and select the best eight for the telescope.
Like its big brother, the James Webb Space Telescope (JWST), which is also an infrared riflescope, the NEO Surveyor will use a heat shield to protect it from the heat of the sun. For infrared detectors to work well, they must be operated at a cold temperature. The shield will handle the sun’s heat as the 20 foot (6 meters) long spacecraft follows an orbit that takes it outside of the moon’s orbit. The observatory continuously scans the sky. It will particularly carefully observe areas near the Sun where asteroids tend to originate on possible earthbound trajectories.
Of course, it is not enough just to find them. One of the main ideas behind the NEO Surveyor is the advance warning. “With NEO Surveyor we want to detect potentially dangerous NEOs when they are years or decades away from possible effects,” said Mainzer. “The whole idea is to give as much time as possible to developing containment measures that will allow us to get them out of the way.” NASA is already working on potential mitigation measures for dangerous asteroids, especially with its Double Asteroid Redirection Mission or DART Mission. DART will test a kinetic impactor to deflect dangerous asteroids away from Earth.
NASA cannot save us from ourselves. But maybe they can protect us from nature. Who knows? Perhaps their efforts will give humanity the time it needs to sort ourselves down here on earth. As Steven Pinker points out in his book The Better Angels of Our Nature: Why Violence Has Declined, humanity is waging fewer and fewer wars, and those we are waging are becoming smaller and more limited.
It would be a shame if an asteroid ended humanity and even life on Earth while we were still struggling to reliably become peaceful. If NASA can do its part, maybe we can.