Experimental Alzheimer’s Drug Said to Succeed in Slowing Cognitive Decline

An experimental Alzheimer’s drug developed by Eisai and Biogen significantly slowed cognitive and functional decline in a large trial of patients in the early stages of the disease, the companies said Tuesday. 

The injected drug, lecanemab, slowed progress of the brain-wasting disease by 27% compared with a placebo, meeting the study’s main goal and offering an apparent win for the companies and potentially for patients and their families desperate for an effective treatment. 

Eisai said the results from the 1,800-patient trial prove the longstanding theory that removal of sticky deposits of a protein called amyloid beta from the brains of people with early Alzheimer’s can delay advance of the debilitating disease. 

“It’s not a huge effect, but it’s a positive effect,” said Ronald Petersen, director of the Mayo Clinic Alzheimer’s Disease Research Center in Rochester, Minnesota, adding that the results were extremely important for Alzheimer’s research. 

“This means that treating amyloid is a step in the right direction,” he said. 

Results considered a “win”

Wall Street analysts, such as Salim Syed at Mizuho Securities, have said the results would be considered a “win” if lecanemab slowed the rate of decline by about 25%, and that shares of both companies could jump on the news. 

Shares of Biogen and Eisai were halted, but shares of Eli Lilly, which is also developing an Alzheimer’s drug, were up 6.7% in after-hours trading. 

Lecanemab, like the companies’ previous drug Aduhelm, is an antibody designed to remove those amyloid deposits. Unlike Aduhelm, lecanemab targets forms of amyloid that have not yet clumped together. 

The so-called amyloid hypothesis has been challenged by some scientists, particularly after the U.S. Food and Drug Administration’s controversial approval of Aduhelm in 2021 based on its plaque-clearing ability rather than proof that it helped slow cognitive decline. The decision came after the FDA’s own panel of outside experts had advised against approval. 

Aduhelm was the first new Alzheimer’s drug approved in 20 years after a long list of high-profile failures for the industry. 

Eisai, leader of the 50-50 partnership’s lecanemab program, is seeking FDA approval under the same accelerated pathway as Aduhelm, with a decision expected in early January. But on Tuesday, the Japanese drugmaker said it would use the new efficacy results to submit lecanemab for traditional FDA review. 

The company said it will also seek authorization in Japan and Europe during its current fiscal year, ending March 31. 

The Phase III trial evaluated the drug’s ability to reduce cognitive and functional decline based on the Clinical Dementia Rating-Sum of Boxes (CDR-SB), a numerical scale used to quantify the severity of dementia in patients in areas such as memory, orientation, judgment and problem-solving and personal care. 

Brain swelling 

The rate of ARIA-E, a brain swelling side effect associated with anti-amyloid treatments, was 12.5% in the lecanemab group, versus 1.7% in the placebo group. 

While the side effect showed up on imaging, many of these cases were not symptomatic, the companies said. Symptomatic brain swelling was seen in 2.8% of those in the lecanemab group and none of the placebo group, they said. 

The trial also tracked the rate of micro hemorrhages in the brain, which occurred at a rate of 17% in the lecanemab group, and 8.7% in the placebo group. 

The total incidence of both conditions was 21.3% in the lecanemab group and 9.3% in the placebo group, rates that fell within an expected range, the companies said. 

Petersen said the side effect was present, but much less than with Aduhelm, and “certainly tolerable.” 

Aduhelm’s approval was a rare bright spot for Alzheimer’s patients, but critics have called for more evidence that amyloid-targeting drugs are worth the cost. 

The controversy and reluctance by some payers to cover Aduhelm led Biogen to slash the drug’s price to $28,000 per year from an initial $56,000. 

But Medicare, the U.S. government health plan for people 65 and older, this year said it would only pay for Aduhelm if patients were enrolled in a valid clinical trial, which sharply curtailed the medication’s use. Since Alzheimer’s is a disease of aging, an estimated 85% of patients eligible for the drug are covered by the government plan. 

The number of Americans living with Alzheimer’s is expected to rise to about 13 million by 2050 from more than 6 million currently, according to the Alzheimer’s Association. Globally, that figure could rise to 139 million by 2050 without an effective treatment, according to Alzheimer’s Disease International. 

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As Ebola Spreads, Ugandan Medical Interns Strike Over Safety

As Uganda reports more deaths from the latest Ebola outbreak in the country, medical interns at the hospital handling most of the cases have gone on strike. The interns say they are not being provided with adequate personal protective equipment against the deadly virus, which causes a hemorrhagic fever. Uganda’s health ministry has so far confirmed five deaths and 18 probable fatalities out of 36 cases.

Ugandan Health officials say they are holding talks with striking interns at central Mubende district’s hospital, which is handling most of the country’s spreading Ebola outbreak.

President for the Federation for Uganda Medical Interns, Dr. Musa Lumumba, says there is not enough personal protective gear for the interns at the hospital.

Speaking to VOA by phone, he called on Uganda’s Ministry of Health to urgently address the issue to protect doctors-in-training. 

“The issue of not having accommodation, so they stay in communities, which communities have got cases of Ebola,” Lumumba said. Protection of those at the frontline. And those at the frontline are the health care workers.”

Uganda Medical Association President, Dr. Samuel Oledo, told VOA one intern, three staff, and a medical student have been confirmed for exposure to the virus and at least three senior health officers (SHO) are showing symptoms.  

“We have 34 interns in Mubende.  And we have less than 12 doctors employed on the ground,” Oledo said. “If you have interns and they are pulling out at once, it’s catastrophic.  And the justifications are clear, honestly.  Results have come out today and one of the SHOs who actually performed surgeries with one of the interns on one case has become positive of Ebola.”

Oledo said they suspect as many as 104 medical students in Mubende hospital have been exposed to the virus.   

Uganda’s Ministry of Health has yet to confirm the exposures and infections of students and staff at the hospital.   

Ministry spokesman Emmanuel Ainebyoona denied there is a lack of protective equipment there to guard against Ebola.  

“All the protective gear to safeguard their life is available,” Ainebyoona said. “But like [with] any other infectious disease, fear will be expected. But we are working to ensure that we engage and counsel.  And ensure that there are teams to respond.”

Despite the spreading virus, Uganda’s Health Ministry said the situation is under control but acknowledged that three people suspected of being infected with the virus fled Mubende’s isolation unit on Monday.

Officials say security has been beefed up since to avoid a repeat. 

Uganda’s Ebola outbreak was first detected last week in Mubende, a central district, but has since spread to neighboring districts Kyegegwa and Kasanda.  

Some schools in Kyegegwa have shut down for two weeks to protect students.

First reports of a possible Ebola outbreak came from Kyegegwa’s Kyaka 11 refugee camp, raising alarm bells of a possible quick spread in the packed camp.  

But testing ruled out an outbreak in the camp.  

After Mubende’s cases were confirmed, the U.N.’s Refugee Agency UNHCR said it added controlled entry measures at refugee settlements.

“We are stepping up some assistance programs that had been curtailed due to lack of funding since July,” said Matthew Crentsil, the UNHCR Uganda representative. “That is procurement of soap. You would agree with me, this is fundamental in curbing the spread of Ebola.”

Uganda has yet to identify the source of the Ebola outbreak, which is the Sudan strain of the virus.  

The Sudan strain is less common than the Zaire strain and has no current, effective vaccine.

Uganda’s last Ebola outbreak in 2019 was the Zaire strain.  It last reported a Sudan strain outbreak in 2012.

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Ebola Cases, Fatalities Rise in Uganda

A highly contagious strain of the deadly Ebola virus in Uganda is causing a quick and significant rise in the number of cases and fatalities, the World Health Organization said.

Uganda health officials declared an outbreak of Ebola a week ago. Five days later, on September 25, they confirmed the disease had infected 36 people, killing 23.

It is the first Ebola disease outbreak caused by the Sudan virus in Uganda since 2012. A vaccine is available to protect adults from becoming infected with the more common Zaire strain of Ebola. However, a similar vaccine does not exist for the Sudan virus.

Ana Marie Henao-Restrepo, WHO co-lead R & D Blueprint for epidemics in the Health Emergency Program, said several possible vaccines are under development.

“We have identified there are three candidate vaccines that have … clinical data, data from humans on safety and homogenicity. It is specifically designed to protect against the Sudan virus and that could be tested in a randomized trial in Uganda, if the Ugandan authorities decide to do so,” she said.

The Ebola virus is spread by contact with an infected patient’s blood or bodily fluids. The WHO reports the median age of cases in Uganda is 26, with 62 percent female and 38 percent male. The disease has a fatality rate of 41 percent.

WHO spokeswoman Carla Drysdale said WHO experts are working with Uganda’s experienced Ebola control teams to reinforce diagnosis, treatment and preventive measures.

“While there is no vaccine to treat Sudan Ebola virus, other health measures such as swift detection, community engagement, isolation of patients, and early supportive care have proven to save lives in similar outbreaks,” Drysdale said. “We must raise awareness in the community that seeking treatment early significantly increases chances of survival.”

While Uganda is struggling to prevent Ebola from spreading, the Democratic Republic of the Congo declared on Tuesday the end of an Ebola outbreak, which emerged in North Kivu Province six weeks ago. North Kivu, which has a vaccine against the Zaire virus, experienced only one confirmed case of Ebola and no deaths.

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Australia Played Role in NASA Asteroid Defense Test

NASA successfully crashed its DART spacecraft into a faraway asteroid Monday, in a test of the world’s first planetary defense system. The experiment, designed to avert a potentially catastrophic meteorite collision with Earth, was supported by Australia’s national science agency.

The aim was to crash the spacecraft directly into the moonlet hard enough to shift its orbital track around a second, larger asteroid.

It will, however, take days or even weeks to establish how much the smaller asteroid’s path has changed.

Rebecca Allen, from Australia’s Swinburne University’s Center for Astrophysics and Supercomputing, told the Australian Broadcasting Corp. that the mission was a great success.

“It was incredible just because it was, you know, a full bullseye, if we can call it that,” she said. “You know, we were expecting maybe it could glance off the side. Is it going to hit exactly where they wanted to and once again NASA does not disappoint with the precision of the impact of the DART spacecraft.”

The DART mission has been supported by Australia’s national science agency, CSIRO.

It manages the Canberra Deep Space Communication Complex, one of three stations around the world that make up NASA’s Deep Space Network and was to receive the final signals from the spacecraft as it approached and hit the asteroid known as Dimorphos.

Planetary defense experts have said that altering the course of a menacing asteroid or comet is preferable to blowing it up and creating multiple pieces that could rain down on Earth.

Australian astrophysicist Kirsten Banks said NASA’s DART mission will test our planetary defenses.

“It is going to change the orbit of that asteroid a little bit around the bigger one,” she said. “We will be able to see a slight change in the periods, how it takes that little moonlet to orbit around the asteroid and quantitatively measure the effectiveness of this particular method of planetary defense.”

The two asteroids that were part of NASA’s DART mission are both very small compared with the asteroid that hit Earth about 66 million years ago, wiping out about 75% of the world’s plant and animal species, including the dinosaurs.

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Category 3 Hurricane Ian Makes Landfall Over Western Cuba 

Hurricane Ian has made landfall over western Cuba just hours after evolving as a major hurricane.

Forecasters at the Miami-based National Hurricane Center say Ian is carrying maximum sustained winds of 205 kilometers an hour, making it a Category 3 storm on the center’s five-level scale that measures a storm’s maximum sustained wind speed and destructive potential.

The storm is just 10 kilometers south of the province of Pinar del Rio, traveling at a speed of 19 kilometers an hour. Officials in Pinar del Rio evacuated tens of thousands of residents ahead of Ian’s arrival and took steps to protect its vital tobacco crops and its related infrastructure.

The NHC says Ian will remain a major hurricane as it travels over the Gulf of Mexico on Wednesday. It is expected to reach the western Gulf Coast of the southern U.S. state of Florida as early as Wednesday and take a direct path towards the cities of Tampa and St. Petersburg. The area has not sustained a direct hit by a major hurricane since 1921.

Forecasters have issued hurricane, tropical storm and storm surge warnings and watches for parts of western Cuba and Florida that are in the current path of Hurricane Ian. The storm is expected to produce between 15 to 25 centimeters of rainfall in western Cuba, with the Florida Keys expected to receive 10 to 15 centimeters and central west Florida to get between 15 to 30 centimeters of rainfall.

Parts of western Cuba are also expected to experience life-threatening storm surges, flash flooding and possible mudslides Tuesday, as well as devastating wind damage. The NHC says parts of Florida’s western coast could see storm surges between 60 to 304 centimeters thanks to Hurricane Ian.

U.S. President Joe Biden has issued an emergency declaration for Florida, authorizing the Federal Emergency Management Agency to coordinate disaster-relief efforts and provide more federal funding. Authorities have issued evacuation orders for hundreds of thousands of residents along Florida’s Gulf Coast. The potential devastation from Ian has even prompted officials with the U.S. space agency NASA to roll its massive Artemis 1 moon rocket and Orion space capsule from its launch pad at the Kennedy Space Center — located on Florida’s eastern coast — back to the Vehicle Assembly Building, further delaying its planned test flight.

Some information for this report came from The Associated Press and Reuters.

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Ian to Evolve into Major Hurricane as it Heads Towards Western Cuba and Florida

Residents from Cuba to western Florida are bracing for the potentially devastating impact of Hurricane Ian as it grows stronger on its trek towards the Gulf of Mexico. 

Forecasters at the Miami-based National Hurricane Center say Ian is moving over the Caribbean Sea carrying maximum sustained winds of 165 kilometers an hour, making it a Category 2 storm on the center’s five-level scale that measures a storm’s maximum sustained wind speed and destructive potential. 

Ian was last spotted 170 kilometers east-southeast of the western tip of Cuba traveling at 20 kilometers an hour. The NHC predicts the storm will evolve into a major Category 3 or 4 hurricane as it moves near or over western Cuba throughout the early morning hours of Tuesday and will remain a major hurricane as it travels over the Gulf of Mexico on Wednesday.   

If the storm continues on its current track, it is expected to reach the cities of Tampa and St. Petersburg on Florida’s western Gulf Coast as early as Wednesday. The area has not sustained a direct hit by a major hurricane since 1921. 

Forecasters have issued hurricane, tropical storm and storm surge warnings and watches for parts of western Cuba and Florida that are in the current path of Hurricane Ian. Hurricane Ian is expected to produce between 15 to 25 centimeters of rainfall in western Cuba, with the Florida Keys expected to receive 10 to 15 centimeters and central west Florida to get between 15 to 30 centimeters of rainfall.   

U.S. President Joe Biden has issued an emergency declaration for Florida, authorizing the Federal Emergency Management Agency to coordinate disaster-relief efforts and provide more federal funding. Authorities have issued evacuation orders for hundreds of thousands of residents along Florida’s Gulf Coast. The potential devastation from Ian has even prompted officials at the U.S. space agency NASA to roll its massive Artemis 1 moon rocket and space capsule from its launch pad at the Kennedy Space Center — located on Florida’s eastern coast — back to the Vehicle Assembly Building, further delaying its planned test flight.   

Some information for this report came from The Associated Press and Reuters.  

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NASA Spacecraft Crashes Into Asteroid in Defense Test

A NASA spacecraft rammed an asteroid at blistering speed Monday in an unprecedented dress rehearsal for the day a killer rock menaces Earth.

The galactic slam occurred at a harmless asteroid 9.6 million kilometers away, with the spacecraft named Dart plowing into the space rock at 22,500 kph. Scientists expected the impact to carve out a crater, hurl streams of rocks and dirt into space and, most importantly, alter the asteroid’s orbit.

“We have impact!” Mission Control’s Elena Adams announced, jumping up and down and thrusting her arms skyward.

Telescopes around the world and in space aimed at the same point in the sky to capture the spectacle. Though the impact was immediately obvious — Dart’s radio signal abruptly ceased — it will take days or even weeks to determine how much the asteroid’s path has changed.

The $325 million mission was the first attempt to shift the position of an asteroid or any other natural object in space.

“We’re embarking on a new era of humankind,” said NASA’s Lori Glaze, planetary science division director.

Earlier in the day, NASA Administrator Bill Nelson reminded people via Twitter that, “No, this is not a movie plot.” He added in a prerecorded video: “We’ve all seen it on movies like ‘Armageddon,’ but the real-life stakes are high.”

Monday’s target: a 160-meter asteroid named Dimorphos. It’s actually a moonlet of Didymos, Greek for twin, a fast-spinning asteroid five times bigger that flung off the material that formed the junior partner.

The pair have been orbiting the sun for eons without threatening Earth, making them ideal save-the-world test candidates.

Launched last November, the vending machine-size Dart — short for Double Asteroid Redirection Test — navigated to its target using new technology developed by Johns Hopkins University’s Applied Physics Laboratory, the spacecraft builder and mission manager.

Dart’s onboard camera, a key part of this smart navigation system, caught sight of Dimorphos barely an hour before impact.

“Woo-hoo!” exclaimed Adams, a mission systems engineer at Johns Hopkins. “We’re seeing Dimorphos, so wonderful, wonderful.”

With an image beaming back to Earth every second, Adams and other ground controllers in Laurel, Maryland, watched with growing excitement as Dimorphos loomed larger and larger in the field of view alongside its bigger companion. Within minutes, Dimorphos was alone in the pictures; it looked like a giant gray lemon with boulders and rubble on the surface. The last image froze on the screen as the radio transmission ended.

Flight controllers cheered, hugged one another and exchanged high fives.

A mini satellite followed a few minutes behind to take photos of the impact. The Italian Cubesat was released from Dart two weeks ago.

Scientists insisted Dart would not shatter Dimorphos. The spacecraft packed a scant 570 kilograms, compared with the asteroid’s 5 billion kilograms. But that should be plenty to shrink its 11-hour, 55-minute orbit around Didymos.

The impact should pare 10 minutes off that, but telescopes will need anywhere from a few days to nearly a month to verify the new orbit. The anticipated orbital shift of 1% might not sound like much, scientists noted. But they stressed that over years, it would amount to a significant change.

Planetary defense experts prefer nudging a threatening asteroid or comet out of the way, given enough lead time, rather than blowing it up and creating multiple pieces that could rain down on Earth. Multiple impactors might be needed for big space rocks or a combination of impactors and so-called gravity tractors, not-yet-invented devices that would use their own gravity to pull an asteroid into a safer orbit.

“The dinosaurs didn’t have a space program to help them know what was coming, but we do,” NASA’s senior climate adviser Katherine Calvin said, referring to the mass extinction 66 million years ago believed to have been caused by a major asteroid impact, volcanic eruptions or both.

The nonprofit B612 Foundation, dedicated to protecting Earth from asteroid strikes, has been pushing for impact tests like Dart since its founding by astronauts and physicists 20 years ago. Monday’s feat aside, the world must do a better job of identifying the countless space rocks lurking out there, warned the foundation’s executive director, Ed Lu, a former astronaut.

Significantly less than half of the estimated 25,000 near-Earth objects in the deadly 140-meter range have been discovered, according to NASA. And fewer than 1% of the millions of smaller asteroids, capable of widespread injuries, are known.

The Vera Rubin Observatory, nearing completion in Chile by the National Science Foundation and U.S. Energy Department, promises to revolutionize the field of asteroid discovery, Lu noted.

Finding and tracking asteroids, “That’s still the name of the game here. That’s the thing that has to happen in order to protect the Earth,” he said.

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NASA’s Asteroid-Deflecting DART Spacecraft Nears Planned Impact With Target 

Ten months after launch, NASA’s asteroid-deflecting DART spacecraft neared a planned impact with its target on Monday in a test of the world’s first planetary defense system, designed to prevent a doomsday collision with Earth.

The cube-shaped “impactor” vehicle, roughly the size of a vending machine with two rectangular solar arrays, was on course to fly into the asteroid Dimorphos, about as large as a football stadium, and self-destruct around 7 p.m. EDT (2300 GMT) some 11 million kilometers from Earth.

The mission’s finale will test the ability of a spacecraft to alter an asteroid’s trajectory with sheer kinetic force, plowing into the object at high speed to nudge it astray just enough to keep our planet out of harm’s way.

It marks the world’s first attempt to change the motion of an asteroid, or any celestial body.

DART, launched by a SpaceX rocket in November 2021, has made most of its voyage under the guidance of NASA’s flight directors, with control to be handed over to an autonomous on-board navigation system in the final hours of the journey.

Monday evening’s planned impact is to be monitored in real time from the mission operations center at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

DART’s celestial target is an asteroid “moonlet” about 170 meters in diameter that orbits a parent asteroid five times larger called Didymos as part of a binary pair with the same name, the Greek word for twin.

Neither object presents any actual threat to Earth, and NASA scientists said their DART test cannot create a new existential hazard by mistake.

Dimorphos and Didymos are both tiny compared with the cataclysmic Chicxulub asteroid that struck Earth some 66 million years ago, wiping out about three-quarters of the world’s plant and animal species including the dinosaurs.

Smaller asteroids are far more common and pose a greater theoretical concern in the near term, making the Didymos pair suitable test subjects for their size, according to NASA scientists and planetary defense experts.

Also, their relative proximity to Earth and dual-asteroid configuration make them ideal for the first proof-of-concept mission of DART, short for Double Asteroid Redirection Test.

Robotic suicide mission

The mission represents a rare instance in which a NASA spacecraft must ultimately crash to succeed.

The plan is for DART to fly directly into Dimorphos at 24,000 kilometers per hour, bumping it hard enough to shift its orbital track closer to its larger companion asteroid.

Cameras on the impactor and on a briefcase-sized mini-spacecraft released from DART days in advance are designed to record the collision and send images back to Earth.

DART’s own camera is expected to return pictures at the rate of one image per second during its final approach, with those images streaming live on NASA TV starting an hour before impact, according to APL.

The DART team said it expects to shorten the orbital track of Dimorphos by 10 minutes but would consider at least 73 seconds a success, proving the exercise as a viable technique to deflect an asteroid on a collision course with Earth — if one were ever discovered. A small nudge to an asteroid millions of miles away could be sufficient to safely reroute it away from the planet.

The test’s outcome will not be known until a new round of ground-based telescope observations of the two asteroids in October. Earlier calculations of the starting location and orbital period of Dimorphos were confirmed during a six-day observation period in July.

DART is the latest of several NASA missions in recent years to explore and interact with asteroids, primordial rocky remnants from the solar system’s formation more than 4.5 billion years ago.

Last year, NASA launched a probe on a voyage to the Trojan asteroid clusters orbiting near Jupiter, while the grab-and-go spacecraft OSIRIS-REx is on its way back to Earth with a sample collected in October 2020 from the asteroid Bennu.

The Dimorphos moonlet is one of the smallest astronomical objects to receive a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable hazard to humankind, NASA estimates that many more asteroids remain undetected in the near-Earth vicinity.

NASA has put the entire cost of the DART project at $330 million, well below that of many of the space agency’s most ambitious science missions.

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Uganda Says Ebola Caseload Rises to 16 as Outbreak Grows

Uganda said on Sunday its Ebola caseload had jumped to 16 people while a further 18 people also likely had the disease, fueling fears of a spreading outbreak that involves a strain for which a vaccine has not yet been found.

In a tweet, the Ministry of Health also said the death toll of confirmed cases remained four while 17 others classified as probable cases had also died. The outbreak had also now spread to three districts, all in central Uganda.

The east African country last week announced the outbreak of Ebola, a hemorrhagic fever whose symptoms include intense body weakness, muscle pain, headache and sore throat, vomiting, diarrhea and rashes among others.

The current outbreak, attributed to the Ebola Sudan strain, appears to have started in a small village in Mubende district around the beginning of September, authorities have said.

The first casualty was a 24-year old man who died earlier this week.

The World Health Organization says the Ebola Sudan strain is less transmissible and has shown a lower fatality rate in previous outbreaks than Ebola Zaire, a strain that killed nearly 2,300 people in the 2018-2020 epidemic in neighboring Democratic Republic of Congo.

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Why is a NASA Spacecraft Crashing Into an Asteroid?

In the first-of-its kind, save-the-world experiment, NASA is about to clobber a small, harmless asteroid millions of miles away.

A spacecraft named Dart will zero in on the asteroid Monday, intent on slamming it head-on at 14,000 mph (22,500 kph). The impact should be just enough to nudge the asteroid into a slightly tighter orbit around its companion space rock — demonstrating that if a killer asteroid ever heads our way, we’d stand a fighting chance of diverting it.

“This is stuff of science-fiction books and really corny episodes of “StarTrek” from when I was a kid, and now it’s real,” NASA program scientist Tom Statler said Thursday.

Cameras and telescopes will watch the crash, but it will take days or even weeks to find out if it actually changed the orbit.

The $325 million planetary defense test began with Dart’s launch last fall.

Asteroid target

The asteroid with the bull’s-eye on it is Dimorphos, about 7 million miles (9.6 million kilometers) from Earth. It is actually the puny sidekick of a 2,500-foot (780-meter) asteroid named Didymos, Greek for twin. Discovered in 1996, Didymos is spinning so fast that scientists believe it flung off material that eventually formed a moonlet. Dimorphos — roughly 525 feet (160 meters) across — orbits its parent body at a distance of less than a mile (1.2 kilometers).

“This really is about asteroid deflection, not disruption,” said Nancy Chabot, a planetary scientist and mission team leader at Johns Hopkins University’s Applied Physics Laboratory, which is managing the effort. “This isn’t going to blow up the asteroid. It isn’t going to put it into lots of pieces.” Rather, the impact will dig out a crater tens of yards (meters) in size and hurl some 2 million pounds (1 million kilograms) of rocks and dirt into space.

NASA insists there’s a zero chance either asteroid will threaten Earth — now or in the future. That’s why the pair was picked.

Dart, the impactor

The Johns Hopkins lab took a minimalist approach in developing Dart — short for Double Asteroid Redirection Test — given that it’s essentially a battering ram and faces sure destruction. It has a single instrument: a camera used for navigating, targeting and chronicling the final action. Believed to be essentially a rubble pile, Dimorphos will emerge as a point of light an hour before impact, looming larger and larger in the camera images beamed back to Earth. Managers are confident Dart won’t smash into the larger Didymos by mistake. The spacecraft’s navigation is designed to distinguish between the two asteroids and, in the final 50 minutes, target the smaller one.

The size of a small vending machine at 1,260 pounds (570 kilograms), the spacecraft will slam into roughly 11 billion pounds (5 billion kilograms) of asteroid. “Sometimes we describe it as running a golf cart into a Great Pyramid,” said Chabot.

Unless Dart misses — NASA puts the odds of that happening at less than 10% — it will be the end of the road for Dart. If it goes screaming past both space rocks, it will encounter them again in a couple years for Take 2.

Saving earth

Little Dimorphos completes a lap around big Didymos every 11 hours and 55 minutes. The impact by Dart should shave about 10 minutes off that. Although the strike itself should be immediately apparent, it could take a few weeks or more to verify the moonlet’s tweaked orbit. Cameras on Dart and a mini tagalong satellite will capture the collision up close. Telescopes on all seven continents, along with the Hubble and Webb space telescopes and NASA’s asteroid-hunting Lucy spacecraft, may see a bright flash as Dart smacks Dimorphos and sends streams of rock and dirt cascading into space. The observatories will track the pair of asteroids as they circle the sun, to see if Dart altered Dimorphos’ orbit. In 2024, a European spacecraft named Hera will retrace Dart’s journey to measure the impact results.

Although the intended nudge should change the moonlet’s position only slightly, that will add up to a major shift over time, according to Chabot. “So if you were going to do this for planetary defense, you would do it five, 10, 15, 20 years in advance in order for this technique to work,” she said. Even if Dart misses, the experiment still will provide valuable insight, said NASA program executive Andrea Riley. “This is why we test. We want to do it now rather than when there’s an actual need,” she said.

Asteroid missions galore

Planet Earth is on an asteroid-chasing roll. NASA has close to a pound (450 grams) of rubble collected from asteroid Bennu headed to Earth. The stash should arrive next September. Japan was the first to retrieve asteroid samples, accomplishing the feat twice. China hopes to follow suit with a mission launching in 2025. NASA’s Lucy spacecraft, meanwhile, is headed to asteroids near Jupiter, after launching last year. Another spacecraft, Near-Earth Asteroid Scout, is loaded into NASA’s new moon rocket awaiting liftoff; it will use a solar sail to fly past a space rock that’s less than 60 feet (18 meters) next year. In the next few years, NASA also plans to launch a census-taking telescope to identify hard-to-find asteroids that could pose risks. One asteroid mission is grounded while an independent review board weighs its future. NASA’s Psyche spacecraft should have launched this year to a metal-rich asteroid between Mars and Jupiter, but the team couldn’t test the flight software in time.

Hollywood’s take

Hollywood has churned out dozens of killer-space-rock movies over the decades, including 1998′s “Armageddon” which brought Bruce Willis to Cape Canaveral for filming, and last year’s “Don’t Look Up” with Leonardo DiCaprio leading an all-star cast. NASA’s planetary defense officer, Lindley Johnson, figures he’s seen them all since 1979′s “Meteor,” his personal favorite “since Sean Connery played me.” While some of the sci-fi films are more accurate than others, he noted, entertainment always wins out. The good news is that the coast seems clear for the next century, with no known threats. Otherwise, “it would be like the movies, right?” said NASA’s science mission chief Thomas Zurbuchen. What’s worrisome, though, are the unknown threats. Fewer than half of the 460-foot (140-meter) objects have been confirmed, with millions of smaller but still-dangerous objects zooming around. “These threats are real, and what makes this time special, is we can do something about it,” Zurbuchen said. Not by blowing up an asteroid as Willis’ character did — that would be a last, last-minute resort — or by begging government leaders to take action as DiCaprio’s character did in vain. If time allows, the best tactic could be to nudge the menacing asteroid out of our way, like Dart.

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