A comet bears down on Earth

NASA Scientist Warns Of ‘Cataclysmic’ Comets: Bigger, Faster Than Asteroids And Could Come Out Of Nowhere

A NASA scientist has warned that comets arcing through our Solar System could pose more of a threat (or at least as much of one) than asteroids that are constantly in the headlines as being a potential danger to life on Earth as we know it. And there are several reasons why a comet headed on a collision course with our planet could be far more devastating, perhaps even producing an extinction level event not seen in tens of millions of years.

Live Science reported recently that the warning has gone out that not only is Earth totally unprepared for defending itself against an imminent asteroid strike but that comets on a collision trajectory would also likely pose greater risks to the planet. Such a collision might even result in the extinction of a majority, if not all, of the major living organisms on Earth.

NASA scientist Dr. Joseph Nuth of the Goddard Space Flight Center in Greenbelt, Maryland, during a news conference at the annual fall meeting of the American Geophysical Union (AGU) held in San Francisco where he made a presentation on the asteroid deflection capabilities and possibilities currently available, suggested that scientists and policymakers should broaden the scope of the potential dangers to Earth hurtling through the Solar System. He said that comets, though often dismissed, are an ever-present threat and it was time that they, too, be considered when taking measures to protect against extra-planetary-generated impacts.

“Comets have largely been ignored by people that are interested in defending the planet.”

The primary reason comets aren’t given their due, Nuth said, was the perception that little can be done to stop comets. This is in part due to the difficulty astronomers have in spotting and tracking them.

“A comet comes out of nowhere, pretty much,” Nuth said during his presentation a few hours prior to the press conference.

In fact, the last near-miss comet, Siding Spring, buzzed Mars, coming to within 87,000 miles (140,000 kilometers) of our neighboring planet. And earlier this year, an asteroid or comet slammed into Jupiter, an event caught on camera by an amateur astronomer, according to CBS News.

Comet in atmosphere
NASA scientist Joseph Nuth warns that comets should be incorporated in talk of space object deflection. [Image by Vadim Sadovski/Shutterstock]

But Earth has to worry about comets the size of Shoemaker-Levy 9, the comet that disintegrated in the atmosphere of Jupiter in 1994 after it was caught by the gas giant’s gravitational field. Scientists estimated, according to a Shoemaker-Levy 9 question and answer webpage set up by Stephen F. Austin State University in Texas, the size of the original comet from the fragments that fell to Jupiter as being approximately 3 miles (5 kilometers) to 6 miles (10 kilometers) across. (In his presentation, when Nuth spoke of giant asteroids that Earth needed to defend against, he referenced, as was reported by the Inquisitr, the “dinosaur killer” asteroid — or comet — that impacted some 65 million years ago, a space rock estimated to have been at least 6 miles (10 kilometers) wide.)

And scientists and agencies need to worry not only about them being spotted late in their orbits and limiting the response time to mount a defense, but also about size and trajectory and velocity. As Nuth explained, comets generally are larger than the average asteroid. The orbital paths of comets have also been found to be elliptical (as opposed to asteroids, where the orbits of most are roughly like Earth’s), with the comet making its journey from the outer reaches of the Solar System, moving in for direct hits (whereas asteroids usually strike the Earth at various angles). Whereas the asteroids travel at an average speed of 44,700 miles per hour (71,940 kilometers per hour), the long elliptical trips of comets see them pick up speed as they approach the sun. For instance, comet Siding Spring was traveling at 125,000 mph (200,000 kilometers per hour) as it passed Mars.

Greater mass. Greater velocity. Greater potential for a direct collision. According to Nuth, these factors provide for “potentially cataclysmic” consequences. He also pointed out that given that extinction-event-level asteroids and meteors collide with the Earth about every 50-60 million years on average and the last impactor, the “dinosaur killer,” hit roughly 65 million years ago, the planet was due for a catastrophic asteroid or comet strike.

Comet strikes Earth
The problem with comets: Dr. Joseph Nuth of NASA says they’re bigger, faster, impact more directly, and could appear virtually out of nowhere. [Image by solarseven/Shutterstock]

The problem, as Nuth pointed out at the presentation, was that there was nothing at present the Earth could do about a hazardous object headed for the Earth unless there was at least five years to prepare or launch some type of interception or deflection mission. This was why along with suggesting that measures be taken to defend the planet more effectively, he also had suggested a possible solution at the presentation.

Nuth suggested a two-part defensive strategy which would employ an “observer” and an “interceptor” spacecraft. The former would study potentially hazardous objects to deem the seriousness of the threat. The latter, which could be outfitted with a nuclear weapon, would be used for destroying or deflecting the object.

“It’s really imperative that we reduce that reaction time,” he said at the news conference.

Other methods of deflection presented at the AGU included the suggestion of the use of lasers to target an incoming object, possibly producing gaseous jet eruptions from said object and knocking it from its collision-course trajectory, and the use of a “kinetic impactor,” described as “basically a giant cannonball,” that would act to batter an asteroid — or comet — off its trajectory.

[Featured Image by Vadim Sadovski/Shutterstock]