The dinosaurs didn't have a space agency; maybe if they did they'd still be here.
If an asteroid threatens to cause serious damage to Earth, planetary defense will try to find and destroy it. planetary defense experts say that impact is the only natural disaster that can be prevented.
It would be difficult to plan an asteroid deflection today, given the questions about how effective a maneuver would be in the real world. Next year, planetary defense will take a big step, conducting its first experiment to determine how such a deflection might play out in reality, thanks to NASA's Double Asteroid Redirection Test, or DART, which launches later this month.
What would a planetary defense mission look like?
DART will slam into an asteroid called Dimorphos in late September or early October of 2022. Scientists will be watching to see how much impact speeds up the space rock's path around Didymos, the first real data about what it might really take to steer a threatening asteroid out of Earth's path.
It's a small change. It's to reduce the chance that we humans end up like the dinosaurs. DART's impact will mark a new relationship between humans and the solar system we live in.
A lot of scale.
Humans have left footprints on the moon, rover tracks on Mars, and metals in the atmospheres of Jupiter and Saturn. Until now, orbital mechanics have been free of human fingerprints, orchestrated only by gravity and chance. It was chaotic in the same way it had always been.
The first time a coalition of humans have come together to purposely tap any one piece of the maelstrom around us, DART's impact will be the first human fingerprints on this eternal dance of the solar system.
"We can do anything in the solar system, we can even move things out of the way," said a University of Delaware geography professor.
A footprint was left on the moon. The image is from NASA.
"Intervening in small-body dynamics is just a huge deal, and it's something that early advocates of planetary defense recognized," said an anthropologist at the University of California Irvine who has studied the planetary defense community.
The experts who suggest looking at the bigger picture of the DART mission aren't saying that planetary defense should be abandoned, just that it's an endeavor worth thinking about from multiple perspectives and different contexts.
Is it important that we figure out if we can dodge an asteroid in the event of an emergency? Natalie Trevio is an independent critical theorist who focuses on space. "But we're looking at our own planet as being on fire."
A damming a river on Earth as an action that might benefit humans but that has broader consequences across the environment was compared by Trevio. What is our responsibility to the solar system? "Treito said." Do we have the right to make these changes to the solar system? What precedent does it set?
Considering rearranging the solar system requires not only looking ahead, but also looking back to evaluate what human histories may influence such an action, and whether we want to create a new, different way.
The idea of being able to move and exploit and destroy natural capital like rocks and asteroids is pinned to an imperial worldview that sees humans as being allowed to do whatever they want.
Who is in the room?
If we like to meddle, where is the line between cute and serious? That line may depend on more than just the scale of effect on orbital dynamics, but also on who is making the decisions about a planetary defense project.
Only a few nations have the spacefaring capability to contemplate embarking on a planetary defense mission, despite the fact that the worst-case impact scenario could destroy on a regional scale and have global consequences. A challenge the planetary defense community often considers is how to ensure that non-spacefaring nations have a say in how Earth responds to an asteroid threat.
It's very specific people in particular agencies who make decisions about how to intervene in outer space. "Oolker said that." What responsibility do those groups have to negotiate the defense and protection of all people?
An artist's depiction of a crater left by DART. The image is from the Science Office.org.
The DART mission stems from yearslong discussions between NASA and the European Space Agency. The DART mission, which will finally launch, will include a cubesat contributed by Italy, and will be followed by a mission called Hera, which will evaluate the debris up close.
The mission may have flown under the radar among the nations that are taking part. The majority of the public are not aware of the mission. No one asked the public what they thought about the idea.
The lack of public input into a mission of this consequence might lead to similar situations where powerful people have made decisions for others on Earth in displays of colonialism, imperialism and militarism. "I think it's interesting that this narrative of being able to save the world is the kind of national savior narrative," he said.
planetary defense technology could be abused. The same technologies that can be used to move something can be used to weaponize something.
For example, turn planetary defense on its head. A nightmare scenario of a group being able to hold an asteroid hostage, looming over other communities was painted by Trevio. I hate to be the killjoy, but to say, 'OK, we can just move something in the solar system to see if we can do it', where does that end up going, and what are the ramifications?' "Treito said."
DART was chosen because scientists don't think the mission can knock the rocks onto a collision course with Earth. If something goes wrong, it may turn a natural disaster into a social one instead of preventing it.
"This is a step-by-step process, and the step that calls itself a practice step in which nothing can go wrong is only one step toward the next step," he said.
There is one threat among many.
How governments, agencies, and the public prioritize different disasters is the most important concern. The DART mission's outreach suggests that threats are not universal, no matter how the future turns out.
"A lot of the rhetoric around this project is about how this is one of the biggest problems that might face Earth, and how the United States and other countries can address it," he said.
The DART mission costs $330 million. NASA's Earth Science Division has an annual budget of $2 billion. Monitoring a changing planet, making a difference in people's lives and giving policymakers the knowledge to make informed decisions are some of the things that the department talks about. Even as biologists say that a sixth mass extinction is underway, it's far from being able to defend the planet from an asteroid.
"I'm interested in what this says about what kind of problems America wants to be seen to be solving or what kind of problems NASA wants to be solving," he said. You are moving a whole asteroid, but you are not making the same innovations for real problems.
The fall of the dinosaurs is one of five mass extinctions that have been recorded in the fossil record. Space rocks aren't responsible for all of the revolutionary periods of upheaval that have taken place on Earth.
An impact is only the beginning. The global killer in an asteroid impact isn't the rock itself, but the rapid extreme climate swings that follow. Climate upheaval can happen with no asteroid in the picture.
Follow her on social media: EmailMeghan Bartels at mbartels@space.com Follow us on social media.
