Tuesday February 19, 2019
Home Lead Story Asteroids Are...

Asteroids Are Falling On Earth’s Surface Twice As Often: Study

This enhanced impact rate poses a threat for the next mass extinction event.

0
//
Asteroids
This Dec. 29, 1968, photo made available by NASA shows craters on the moon. For the past 290 million years, giant rocks from space have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study. VOA

Giant rocks from space are falling from the sky more than they used to, but don’t worry.

For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.

But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate. NASA’s list of potential big space rock crashes shows no pending major threats. The biggest known risk is a 4,200-foot (1.3-km) wide asteroid with a 99.988 percent chance that it will miss Earth when it whizzes very near here in 861 years.

Tell that to the dinosaurs. Most scientists think dinosaurs and a lot of other species went extinct after a huge space rock crashed into Central America about 65 million years ago.

Earth, Asteroids
Taurids meteor shower lights up the sky. The risk of asteroids hitting the Earth has grown over the years. Wikimedia

“It’s just a game of probabilities,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist. “These events are still rare and far between that I’m not too worried about it.”

Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 12 miles (20 km) wide and came up with the dates of them. It takes a space rock that’s half a mile (800 meters) wide to create holes that big.

The team counted 29 craters that were no older than 290 million years and nine between 291 million years and 650 million years old.

But we can see relatively few big craters on Earth because the planet is more than 70 percent ocean and past glaciers smoothed out some holes, said University of Toronto planetary scientist Rebecca Ghent, a study co-author.

Earth, Asteroids
These rocks were rare survivors from a very different time on Earth. Pixabay

Extrapolating for what can’t be seen brings the total to about 260 space crashes on Earth in the last 290 million years. Adding in other factors, the science team determined that the current space crash rate is 2.6 times more than the previous 700 million years.

Craters older than 650 million years are mostly wiped off on Earth by glacial forces so the scientists used impact craters on the nearby moon as a stand-in for holes between 650 million and 1 billion years old. The moon is a good guide for estimating Earth crashes, because it is close enough to be in the same bombardment path and its craters last longer.

Mixed reactions

So what happened nearly 300 million years ago?

“Perhaps an asteroid family was broken up in the asteroid belt,” Mazrouei speculated. The space rocks then headed toward the Earth and moon, and the planet got slightly more because it is a bigger target and it has higher gravity, Ghent said.

Oldest known asteroid family
An asteroid family. Wikimedia

Outside scientists are split about the research. Jay Melosh at Purdue said he found the number of craters too small to come to a reasonable conclusion, but Harvard’s Avi Loeb said the case was convincing.

Also Read: Newly Discovered Super-Earth Exoplanet May Sustain Primitive Life

Humans might not have emerged without mass extinctions from space rocks about 250 million and 65 million years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”

“This demonstrates how arbitrary and fragile human life is,” Loeb wrote. (VOA)

Next Story

Anticipated Problems That May Effect NASA’s Mars Mission

According to results from the first eight analog space crews, presented at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, D.C., the astronauts are able to successfully complete tasks between 20 and 60 per cent of the time.

0
NASA has formalised plans to send a manned mission to Mars, a journey that could involve 250 million miles of travel on a small spacecraft.  Pixabay

Researchers are developing a predictive model to help NASA anticipate conflicts and communication breakdowns among crew members and tick off problems that may make or break the Mission to Mars.

NASA has formalised plans to send a manned mission to Mars, a journey that could involve 250 million miles of travel on a small spacecraft.

To understand the psychological demands of this Mars journey, Northwestern University has charted a multi-phase study conducted in two analog environments — HERA in the Johnson Space Center in Houston and the SIRIUS Mission in the NEK analog located in the Institute for Bio-Medical Problems (IBMP) in Russia.

The varsity will study the behaviour of analog astronaut crews on mock missions, complete with isolation, sleep deprivation, specially designed tasks and mission control, which mimics real space travel with delayed communication.

Mars
NASA has formalised plans to send a manned mission to Mars, a journey that could involve 250 million miles of travel on a small spacecraft. 
Pixabay

“Astronauts are super humans. They are people who are incredibly physically fit and extremely smart,” said Leslie DeChurch, Professor at Northwestern.

“We’re taking an already state-of-the-art crew selection system and making it even better by finding the values, traits and other characteristics that will allow NASA to compose crews that will get along,” DeChurch added.

HERA’s capsule simulator houses astronauts for up to 45 days — a mock mission control outside the capsule — that augments the realism with sound effects, vibrations and communication delays.

space
According to results from the first eight analog space crews, presented at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, D.C., the astronauts are able to successfully complete tasks between 20 and 60 per cent of the time. Pixabay

Those on the inside undergo sleep deprivation and try to perform tasks. The researchers collect moment-to-moment metrics about individual performance, moods, psychosocial adaptation and more.

According to results from the first eight analog space crews, presented at the American Association for the Advancement of Science (AAAS) annual meeting in Washington, D.C., the astronauts are able to successfully complete tasks between 20 and 60 per cent of the time.

Also Read: Iran Doubts Europe’s Efforts To Keep Nuclear Deal Alive

The next phase of the research, which began on February 15, involves using the model to predict breakdowns and problems a new HERA crew will experience and making changes to “who works with whom, on what, and when”.

The experiment on the SIRIUS analog in Moscow, will begin on March 15, where four Russians and two Americans, will undertake a 120-day fictional mission around the moon, including a moon landing operation. (IANS)