Space­craft would crash into an as­ter­oid, shove it off course

DART project is NASA’s plan to avert catas­tro­phe.

Dayton Daily News - - NATION & WORLD - By Tim Pru­dente

— A team of BAL­TI­MORE 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.

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