Asteroids and comets that come close to Earth can pose a very real threat to our planet. Impacts of any size can cause serious damage on a local scale, and larger near-Earth objects (NEOs) have the potential to cause regional or even global devastation. Although major impacts are very rare, they are bound to happen if we don’t take steps to prevent them.
Planetary defense is the effort to make sure that major impacts don’t happen, and it needs your support.
Humans have the technological capabilities to spot asteroids, track their trajectories and calculate the likelihood of an impact years and even decades before a collision might occur. This is important: the earlier a threat is identified, the easier it is to deflect it. Starting in the 1990s, space agencies and observatories around the world began scanning the skies for NEOs. You can find most of these efforts listed in the International Asteroid Warning Network, which coordinates planetary defense efforts around the world. There is hardly full global participation, though. Every country in the world should be funding astronomers to look for asteroids, since impacts have the potential to affect every country in the world.
Ground-based observing isn’t enough. It is limited by weather, geographical location, the Sun, and the growing presence of satellite mega-constellations. NEOs also tend to be extremely small and dark, making them difficult to detect in wavelengths of light visible through our atmosphere. This limits the rate at which we can discover hazardous objects.
The solution to this is a dedicated space telescope designed to detect the heat signatures of NEOs. In deep space, there are no day/night cycles, no clouds, and no satellites to get in the way of detection. The telescope would scan in the infrared — a wavelength blocked by Earth's atmosphere — to find and characterize asteroids by their warm glow against the cold backdrop of space. Once launched, a space-based solution could find more asteroids in 10 years than all the ground-based telescopes will find in the next three decades. This idea has broad support; in 2019 the United States' National Academies of Sciences released a report that endorsed the concept.
In response, NASA began formal work on the NEO Surveyor mission. This is a modest project, with a total budget less than a single year of funding for the JWST at its peak. But due to political disruptions in funding and higher-priority projects at NASA consuming attention, progress is far from certain. No other space agencies are currently developing space telescopes to hunt for NEOs. NEO Surveyor is it.
Humans also have the potential to create technologies for deflecting an incoming asteroid, given enough warning time. NASA's Double Asteroid Redirection Test (DART) mission launched in 2021 and will test the kinetic impactor technique — smashing into an asteroid to change its trajectory. This is the first and only mission ever to validate asteroid deflection by this method. But this should be the start; more deflection technology needs to be tested to provide humans with options should our species face a serious threat.
It is within humanity’s power to avoid disaster if we take the asteroid threat seriously and invest in detection and deflection work. All of the necessary efforts benefit from sustained and coordinated investment from every country in the world. Like a pandemic, the world's ability to manage a disaster will depend on basic research and investments made beforehand.
This is where you come in.
Wherever you live, you can help. Government spending on public programs reflects the interests of the people. When you tell your government leaders that you value investment in planetary defense — which includes finding, tracking, characterizing, and deflecting NEOs — you are doing your part to help make these investments possible.
The Planetary Society equips and empowers people like you around the world to advocate for planetary defense investments. Learn more about our advocacy work, including our global Day of Action.