In 2021, NASA announced that they were going to crash a spacecraft into an asteroid -- on purpose. But this was no "hold my beer" moment; the reason pour faire le smashy-smash was a live-fire demo of "Earth's first planetary defense system." A big enough asteroid can wreck the day of every living human, on and off planet. So, twenty years after the 1998 box office sunburn Armageddon, NASA launched the Double Asteroid Redirection Test (DART). Now, Chinese state media reports that China has a plan to step up with its own asteroid redirect mission.
Space Day is a pretty big deal in China. So, this year's Space Day was an auspicious day to announce this mission of shared global guardianship. During an interview on China Central Television, China National Space Administration (CNSA) deputy head Wu Yanhua detailed a sweeping new asteroid defense initiative.
First, Wu said, China will build out a "near-Earth asteroid monitoring and defense system" to protect from asteroid impacts. Such a system would include an early warning array, along with other relevant defense tech, which is TBD. But Wu also floated an ambitious plan to have an asteroid-redirecting spacecraft in the sky no later than Space Day, 2025.
We don't yet have specifics on launch, nor even a render of the design. This newly announced mission is still very much in the planning phase, said Wu, although Chinese media intimated that the project has already been greenlit by the Chinese National Space Agency. However, DART launched from Vandenburg on a SpaceX Falcon 9 rocket. Presumably, this newly announced Chinese spacecraft would launch on a rocket in the Long March family. Long March is a Chinese line of workhorse launch vehicles with various lift capacities. LM-8 is the closest comparator to the Falcon 9, while the LM-9 is a super-heavy not unlike the American SLS Block 1.
Momentum
Like DART, the planned Chinese kinetic redirect would single out an asteroid to crash into. Unlike DART, however, this new mission would choose an asteroid that poses some future threat to the planet. DART picked the moonlet of a benign asteroid, Dimorphos (aka "Didymoon(Opens in a new window)"), for a proof of concept. In short, hoo boy you do not want to miss the one that matters, so practice on the ones that don't.
Some space missions, like solar physics, study and have to account for spooky quantum phenomena. Others deal with relativistic effects, or do sophisticated science on lasers and electromagnetism. DART, however, is refreshingly direct. It's pure kinematics.
You may have heard of f=ma, Newton's second law of physics: force equals mass times acceleration. If you're (un)lucky enough to have endured freshman physics, you may also have encountered the formula for momentum: p=mv. Momentum equals mass times velocity. And that's how DART does its work. A small thing traveling very fast can apply the same amount of force in a collision as a big thing going slow -- for example, the OMG particle, a single proton of cosmic origin we clocked at 99.99999999999999999999951% C, with the kinetic energy of a line drive(Opens in a new window). So we're chucking half the equivalent mass of a VW Bug at this kilometer-size asteroid.
DART is flying Deployable Space Systems Roll-Out Solar Arrays (ROSA) for the first time in deep space, featuring powerful APL-developed Transformational Solar Array concentrators. The arrays power NASA’s Evolutionary Xenon Thruster - Commercial (NEXT–C) ion engine, an electric propulsion system developed by Glenn Research Center in collaboration with Aerojet Rocketdyne. (Image Credit: NASA/Christopher J. Lynch)
NASA expects that DART will hit Dimorphos' surface at fifteen thousand miles an hour. We don't know how the new Chinese kinetic redirect spacecraft will build its momentum. But we do know that DART can attain its ludicrous speed because of its xenon-powered NEXT-C ion engine. Over more than ten thousand hours, the breath of force from that ion engine will bring DART up to speed.
Must Be Cool in That Shade
Song Zhongping, a Chinese military expert and space observer, told the Chinese state-run Global Times(Opens in a new window) that "currently the US and Russia are also building asteroid monitoring systems, and China's defense system could be an important supplement in addressing the threats of asteroids hitting Earth."
"This is another practical solution that China proposes to build a community with a shared future for mankind, and it is the duty for a major space power to protect mankind from possible disasters that could end the entire human civilization," Song said, during the Space Day interview.
China's stated aims for the mission are straightforward. They frame the mission in terms of shouldering a global burden of defense against asteroid impact. And it is a global burden of defense. But nothing comes out of the Chinese propaganda machine by accident. It's impossible to miss China's delicate implication that while Russia's nouveau-riche space mafioso wannabe Rogozin spends his time griefing civilians on Twitter and threatening the ISS -- while Putin sacrifices the futures of millions of people on the altar of his ambition -- China will nobly spread its sheltering arms, to the benefit of all. They didn't mention the war in Ukraine. They didn't have to.
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