To save the Earth someday, team builds spacecraft to crash into an asteroid and shove it off course

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A team of scientists, astronomers and engineers meets weekly in a conference room on a Howard County, Md., research campus and plans to save the world.

"Keep calm and carry DART," reads a poster on the wall.

DART—the Double Asteroid Redirection Test—is their plan to avert catastrophe. It's also NASA's first mission not to explore space, but to defend against it.

The research team at the Johns Hopkins University Applied Physics Laboratory in Laurel plans to launch a spacecraft, speed it up really fast and smash it into an asteroid. BOOM!

The impact, they hope, will bump the big space rock off course—actually more like nudge it slightly. Someday, the thinking goes, this method may save humans from the fate of the dinosaurs.

"Kind of like a big missile," said Elena Adams, the mission's lead engineer. "It's very exciting. You are actually doing something for the fate of humanity."

An estimated 100 tons of space debris falls to Earth every day, according to scientists with the NASA's Jet Propulsion Laboratory at the California Institute of Technology. This debris is mostly dust and sand.

Occasionally, space sends something bigger.

In February 2013, a fiery meteor cut across the Siberian sky. It came streaking down as fast as 40,000 mph. Then came a mid-air explosion, a flash and boom.

The shock wave blew out windows across the Russian city of Chelyabinsk. A factory roof collapsed. More than 1,000 people were hurt, mostly from shattered glass. Scientists estimate the meteor unleashed a force stronger than the atomic bomb detonated in Hiroshima.

The rock was about the size of a school bus. That's a pebble compared to a meteor believed to have exploded over remote Siberia in 1908, flattening hundreds of square miles of forests. Researchers estimate that fireball equaled 185 Hiroshima bombs and heated the air to near 50,000 degrees. If the Tunguska meteor had arrived, say, three hours later, it could have obliterated Moscow, said Lindley Johnson, whose title with NASA is planetary defense officer.

"That probably would have changed the entire history of the 20th Century," said Johnson, who runs NASA's asteroid-defense programs. "These are natural disasters that we need to be aware of."

Some time in a span of several hundred-thousand years, scientists say, an asteroid even larger could strike Earth and wreak global disaster. They believe a meteor 8 to 10 kilometers in diameter crashed into the Gulf of Mexico 65 million years ago and killed off the dinosaurs.

"We've found all the nearest asteroids that size. We're safe from that," said Paul Chodas, who runs an asteroid search team at the NASA lab in California.

But smaller asteroids can unleash megatons of energy too.

"Even down to the 1-kilometer size, if it hits in the right spot, could cause global devastation," Chodas said. "It's the small asteroids that pose the risk."

In the 1990s, Congress ordered NASA to locate dangerous asteroids in the solar system. Researchers today aim to catalogue the orbits of 90 percent of asteroids 460 feet or bigger.

They predict 25,000 of them hurtle through the solar system. Chodas said they have found and charted about a third of them. The researchers can calculate each asteroid's trajectory decades into the future.

Scientists have long debated what to do if they discover one on a collision course with Earth.

Hollywood portrayed such events in "Deep Impact" and "Armageddon." In both movies, mankind narrowly escapes doom by planting nuclear bombs and blowing the asteroids to pieces.

It's not that easy.

NASA has considered nuking an asteroid with warheads, but that risks turning a single incoming rock into a shower of debris as happened in "Deep Impact." Another plan calls for flying a spacecraft beside the asteroid and gradually drawing it off course like a gravity tractor.

DART offers a third strategy, and will be the first given a live test.

"It's the simplest and most effective," Chodas said.

Now the team at the Hopkins laboratory in Laurel has begun the final design and construction of the DART spacecraft. About the size of a Honda Civic, it's scheduled for launch in summer 2021.

While it sounds simple, the crash mission involves some tricky engineering.

The target is the tiny moon of an asteroid. The two bodies are collectively named Didymos or Greek for "twin." They orbit the sun between Earth and the Asteroid Belt. The moon is not much bigger than the Washington Monument in D.C. - minuscule in the scale of space.

"This is by far the smallest object anyone has ever flown a spacecraft into," said Andy Cheng, the mission's co-lead and chief scientist in APL's space department.

The spacecraft will be powered by solar panels that unfurl like wings. Its journey will take more than one year, and the researchers will be flying blind mostly.

"We don't see the moon of the asteroid until we're just an hour away," said Adams, the engineer. "That last hour is going to be really thrilling."

They plan for DART to reach speeds as fast as 15,000 miles per hour. The crash in October 2022 will fling debris from the asteroid moon. A small satellite will accompany the DART spacecraft to measure the effect.

The team wants to hit the asteroid moon with enough force to bump it, but not break it apart. The moon orbits the asteroid at a speed of about seven inches per second. They hope to change the speed by about a centimeter per second.

"We're just going to give it a love tap," said Andy Rivkin, the mission's other co-lead and planetary astronomer at APL.

In theory, a series of taps over time could deflect an asteroid off a course for Earth.

One impact may suffice if scientists have enough warning time. An imminent asteroid strike, however, would require multiple launches and impacts.

"You could have a constant stream," Rivkin said. "Each one nudges it a bit more."

It's humanity's best plan to save Earth, but one the team hopes they never have to use.

Explore further

Asteroid-deflection mission passes key development milestone

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Feb 08, 2019
"The team wants to hit the asteroid moon with enough force to bump it, but not break it apart. The moon orbits the asteroid at a speed of about seven inches per second. They hope to change the speed by about a centimeter per second."

I have a bad feeling about this.

Feb 09, 2019
Give it a paint job while you're there. I think they should put a launch-able device in front of the asteroid that can vaporize and spread reflective paint on one side and maybe a light absorbing paint on the other. If the rock were to heat up on one side but not the other; this could possibly create a course changing effect. If nothing else it would be easier to track. You just need small movement over a long period of time.

Feb 10, 2019
I used to consider the impact idea a fairly sound one, until we got better information on the makeup of most of the asteroidal type bodies, and they would also have to include things like comets, and ones that have broken into comet trains like Shuemaker-Levy9 did.

I have since come to think that a soft-landing thrusters that ejected a net that would expand to fit the surface and then harden or freeze to cover the near surface and give some solidity and even base for the rocket motor to push against, and then to use the thruster to change the course of the object, perhaps even change the speed enough to bring it to a parking orbit around Luna, within reach of further science experiments and miners on the cheap.

I would talk to Mr Musk about the feasibility of using a modification of setup to upright land a series of fairly large thrusters, like the Falcon 9, only fully fueled etc upside down, with the Merlin Space engine and that much fuel/oxidizer you can do a lot.

Feb 10, 2019
If they got this, why not have the spacecraft snuggle up to the asteroid and turn on the rockets instead of wasting the spacecraft?

Be the same delta-V either way, wouldn't it?

Feb 10, 2019
That is what I figure DS, and they would have the option of 'parking it' in a nice orbit and then even those rockets could be recycled. I had always worried about breakup of the mass and the problem of a large number of smaller, yet still dangerous meteors and meteorites.

Since Musk has been landing em upright Here, in high G, comparatively, he should be able to find a way to soft land on the incoming item in question, control it's tumble, and then boost it to a safer orbit, hopefully one that we can then later access.

But I agree, why waste the delta-V in an uncontrollable impact scenario when the same delta-V could be used in a controlled fashion and possibly gain us a treasure trove of scientific information as well as new exploitable resources.

Feb 10, 2019
After a brisk search, I've found the NASA Deep Impact's crater was about 150 metre diameter, that 10 km/s 'roadkill' the equivalent of 5 tonnes of TNT, and the comet's orbit shifted by, at most, 10 cm. About the width of your palm.

IMHO, those results do not scale well to any 'diversion' mission, especially when you consider the effects of 'gravitational focusing'...

As I understand it, the outer layer of the comet was more 'de-gassed', held less volatiles than predicted. Reaching the juicier inner portions might displace more stuff, perhaps produce some 'reaction' via jetting. But how ?


Feb 10, 2019
Who will rid us of these Rockets

The age old 1000 year prehistoric problem
emergeths once more
the inadequacy of rockets
who will rid us of these rockets
for propulsion engines
Suitable in this 2019 year of our Lord

Feb 10, 2019
My first concern. Are they certain that Didymos B is a solid rock & not a rubble pile?

If the force of the strike hits solid rock, could it propel the moon-lite B into the side if Didymos A?

If Didymos A is solid rock?
I would bot be concerned. It has sufficient mass to flick-off a gnat like B.

However, if B is a solid rock?
& A turns out to be gravel?
Unintended consequences?

I wikied (65803) Didymos.
& found "... Didymos orbits the Sun at a distance of 1.0–2.3 AU once every 2 years and 1 month (770 days) ..."

That orbit outside the Earth's orbit, makes me nervous.

I would prefer such experiments were performed inside the Earth's orbit.
i.e. where the Sun's gravity well would be pulling any unexpected results AWAY from the Earth.

Yah know, belt & suspenders & a few big safety pins wouldn't hurt!

Feb 11, 2019
Let us rejoice that in the 1960s we invented nuclear rockets.

These produce very significant thrust per amount of mass. I agree with the others that suggest soft landing, and recommend a nuclear rocket either tethered or surface mounted to our unfriendly space rock. The rocket can be directed to move the rock/comet trajectory enough to pass by earth, and can also provide continuous telemetry of progress. This is not likely from a crashed rocket sporting an orbiter that can do more than watch. Since nuclear fuel can be made concentrated enough to make continuous heat, it can protect the vitals of the rocket and the electronics with warmth. The electronics would be radiation hardened to handle this. I suggest final assembly in orbit with the fuel added last via a special extreme crash worthy fail/safe metal capsule with an automated access port operated by the rest of the rocket system.

Drive on!!!

Feb 11, 2019
If you catch it early enough, an ion rocket would do. Cheaper, too.

Feb 11, 2019
@Da Schneib, I agree, but the farther away the unfriendly rock is, the less detectable it is. This may be more workable with current tech.

Feb 11, 2019
As I understand it, one nightmare scenario is a belated sighting of a close pass by a ~200 metre lump, with orbital calculations showing 'probable impact' within a couple of years. Or, worse, at its next approach in nine months....

At least sub-500 metre objects may shatter from 'throw the kitchen sink' tactics, with regional militaries hastily re-purposing missile and anti-missile systems to take on those still-scary fragments as they hit the stratosphere. A little radioactivity, some iodide tablets etc being much, much better than the alternatives...

For 'forthcoming events' regarding PHAs, check out...

Feb 11, 2019
Are you talking about nuclear "powered" or nuclear "armed" missiles?

Cause I missed the headlines where anyone has announced that they have built, successfully launched & recovered a nuclear powered rocket?
"Orion yesterday.
& Orion tomorrow.
Never Orion today..."

My limited understanding is that nuclear armed missiles are generally of deliberately limited range. Carrying small multiple warheads. Pre-designated for hopefully kinda almost precise targeting?

Do any of those warheads have the capacity to reach, intercept an incoming rock at approx 20+ Km velocity?

& wouldn't that be way too close to the Earth to prevent major destruction? As well as irradiating the rock's elemental materials into dangerous isotopes?

Cause, no situation is so bad? We must try our best, to make it worse?

Feb 12, 2019
Good point, rrwilliejoe
Nuclear warheads are not an option.
Now I'm almost certain that most humans have purchased apples, lemons, potatoes, and oranges that come in a flexible plastic bag with small holes. If the-powers-that-be decided to manufacture such a flexible bag that would fit around a flying object such as an asteroid with room to spare, such a "bag" could be made of very strong material in low-earth-orbit piece by piece and then heat-sealed to make a proper bag to contain an asteroid, meteor, whatever.
The bag could remain ready in LEO, waiting for the time when it is needed. It could be folded and, when needed, it could be unfolded and readied in the general shape of a "tunnel" to capture the flying object. It would also prevent the object from breaking apart. It can be towed into a safe orbit where it will either be pulled into the Sun; or be kept in an orbit that doesn't affect Earth or Moon or other planets.
Several of them could be made and sent up to orbit.

Feb 12, 2019
Yeah, a robot-trawler using nano-strengthened, synthesized spider webbing for netting.

Assembled by an orbiting automated factory out of whatever materials are available in orbiting debris.
Don't care if it's ugly, the robot-trawler has work to do.

& if necessity bitches at us?
The craft can be sacrificed to fend off a late-detected rock. Hopefully in the right direction? i.e. away from Earth.

"Hey Moon!
Meet my little friend!"

Feb 13, 2019
Nuclear rockets were tether stand tested and proven powerful, but not deployed, because of radiation. The test site is still radioactive. I suggest: Make the payload of conventional rockets the "nuclear rocket" that provides "push" to unwelcome rocks. More bang from the weight involved. Send more than one. Whatever works.

Feb 13, 2019
Catch 22

The first hurdle
we cannot see them till there on us
the second hurdle
we have no means to push them out the way
the third hurdle
what ever means to push them out the way is pointless
the asteroid strikes earth before we strike the asteroid
in summary
We have no means to strike
If we saw the asteroid, we cannot strike in time even, if we had the means to strike
A bit of a bind as to what to do
or we could do what our ancestors did
Look to heavens and admire the view, while we think this one out again!

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