asteroid coming close to earth

It’s International Asteroid Day!

There are more than 700,000 known asteroids, but how much do you know about these rocky remnants left over from the birth of our solar system 4.6 billion years ago? 

Today, June 30 is International Asteroid Day. Here are some things to know about our fascinating space rubble.

1. A Place in Space 

Asteroids—named by British astronomer William Herschel from the Greek expression meaning “star-like"—are rocky, airless worlds that are too small to be called planets. But what they might lack in size they certainly make up for in number: An estimated 1.1 to 1.9 million asteroids larger than 1 kilometer are in the Main Belt between the orbits of Mars and Jupiter. And there are millions more that are smaller in size. Asteroids range in size from Vesta—the largest at about 329 miles (529 kilometers) wide—to bodies that are just a few feet across.

2. What Lies Beneath 

Asteroids are generally categorized into three types: carbon-rich, silicate, or metallic, or some combination of the three. Why the different types? It all comes down to how far from the sun they formed. Some experienced high temperatures and partly melted, with iron sinking to the center and volcanic lava forced to the surface. The asteroid Vesta is one example we know of today.

3. Small Overall 

If all of the asteroids were combined into a ball, they would still be much smaller than the Earth’s moon.

4. Except for a Big One

In 1801, Giuseppe Piazzi discovered the first and then-largest asteroid, Ceres, orbiting between Mars and Jupiter. Ceres is so large that it encompasses about one-fourth of the estimated total mass of all the asteroids in the asteroid belt. In 2006, its classification changed from asteroid to  as a dwarf planet.

5. Mission to a Metal World 

NASA’s Psyche mission will launch in 2022 to explore an all-metal asteroid—what could be the core of an early planet—for the very first time. And in October 2021, the Lucy mission will be the first to visit Jupiter’s swarms of Trojan asteroids.

6. Near-Earth Asteroids

The term ‘near’ in near-Earth asteroid is actually a misnomer; most of these bodies do not come close to Earth at all. By definition, a near-Earth asteroid is an asteroid that comes within 28 million miles (44 million km) of Earth’s orbit. As of June 19, 2017, there are 16,209 known near-Earth asteroids, with 1,803 classified as potentially hazardous asteroids (those that could someday pose a threat to Earth).

7. Comin’ in Hot 

About once a year, a car-sized asteroid hits Earth’s atmosphere, creates an impressive fireball, and burns up before reaching the surface.

8. But We’re Keeping an Eye Out

Ground-based observatories and facilities such as Pan-STARRS, the Catalina Sky Survey, and ATLAS are constantly on the hunt to detect near-Earth asteroids. NASA also has a small infrared observatory in orbit about the Earth: NEOWISE. In addition to detecting asteroids and comets, NEOWISE also characterizes these small bodies.

9. Buddy System

Roughly one-sixth of the asteroid population have a small companion moon (some even have two moons). The first discovery of an asteroid-moon system was of asteroid Ida and its moon Dactyl in 1993.

10. Earthly Visitors 

Several NASA space missions have flown to and observed asteroids. The NEAR Shoemaker mission landed on asteroid Eros in 2001 and NASA’s Dawn mission was the first mission to orbit an asteroid in 2011. In 2005, the Japanese spacecraft Hayabusa landed on asteroid Itokawa. Currently, NASA’s OSIRIS-REx is en route to a near-Earth asteroid called Bennu; it will bring a small sample back to Earth for study.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

3

Can we deflect asteroids?

In the edition of Space, Euronews correspondent Jeremy Wilks reports from the Observatory of the Côte d’Azur in the south of France on a unique mission to deflect an asteroid.

Asteroids have the potential to cause a catastrophe – a small asteroid could wipe out an entire city, while a large one could mean the end for us all.

It’s a threat we’re aware of, and which scientists and engineers are working to overcome. Among them is leading expert Patrick Michel, from the Observatory of the Cote d’Azur.

“An asteroid is a small rock which is one of the bricks left over from the formation of our planets. Some of them are dangerous, because although most are out there between Mars and Jupiter, in what we call the asteroid belt, there are some that have a trajectory that crosses that of Earth. And those are the ones that pose a threat,” he points out.

It’s a threat that’s limited – a sizeable asteroid strike only happens every ten thousand years or more- but it’s a threat to be taken seriously.

“Even if the frequency of impact is very low, like the probability of winning the lottery is very low, but there are those that do win,” adds Patrick Michel.

With that threat looming above us, the world’s space agencies are swinging into action.

Just recently two missions, one American, and one Japanese, set off to visit asteroids, and bring back samples to be studied on Earth.

Now ESA and NASA are planning to try something that’s never been tried before in a joint project called AIDA.

“AIDA is I think the most audacious mission after Rosetta. It’s a mission where we plan to test for real a mitigation technique called kinetic impactor, to actually test if we can deflect asteroids. This is the main objective of this international cooperation between ESA and NASA,” explains Ian Carnelli, AIM project manager.

The mission outline goes like this: ESA’s AIM spacecraft launches in the year 2020 to an asteroid system called Didymos, in which a large asteroid is orbited by a small asteroid dubbed Didymoon.

It surveys that moon, and then six months later NASA’s DART spacecraft arrives and smashes into Didymoon, while AIM records what happens.

“The impact will be spectacular. DART will arrive at about 6 kilometres per second. AIM will be at about 100 kilometres distance to make sure we’re away.

‘The difference that DART will make is to change the speed of the moon around the main asteroid by about half a millimeter per second. This is very small. But it will generate a change in time of about 10 minutes over 11 hours, and this we can measure very accurately,” he stresses.

Before that can happen there’s a lot to learn.

At ESA’s technical centre in the Netherlands the engineers are simulating the scene that the AIM spacecraft will encounter when it arrives at the asteroid.

Right now we know that the small Didymoon orbits the larger asteroid, but we don’t know much else.

“We have a rough idea of how it looks like, and from what we’ve observed this is how we think it more or less looks like, but the operative word is on ‘more or less’, we’re not entirely sure. And we won’t be sure until we get there,” says Irene Huertas, Guidance, Navigation and Control Engineer, SERCO for ESA.

Irene uses this facility to set up the spacecraft’s camera to be ready to do a thorough job of observing the impact.

“We can shoot different scenes with darker asteroids, lighter asteroids, a very rocky surface, a very smooth surface, a combination of both. A darker moon, a lighter main body.

‘What AIM will do after this impact has taken place is it’s going to take more images, and it’s going to see what happens, what it looked like before the impact, what it looked like after the impact, and see how much this orbit around the big asteroid has changed, how much have we displaced the little moon,” she says.

This double asteroid system was chosen because it comes close to Earth but poses no threat to our planet

However objects the same size as the little moon could mean trouble if they’re heading in our direction.

“Didymoon is about 163 metres in diameter, and this is a very interesting size, because it’s representative of a type of asteroid that if it were to hit the Earth would generate casualties, independently of the impact point. So if it’s in the middle of the ocean it would generate a tsunami, and if it’s any place on surface, on the ground it will reach inhabited areas, so it’s a very important type of asteroid,” explains Ian Carnelli.

Back in Nice and asteroid expert Patrick Michel underlines that this mission is a true experiment.

We’ve made simulations, but we really don’t know if we can deflect an asteroid.

“The response of an object to an impact depends a great deal on its internal structure. If my target is a metal bar the response won’t be the same as if my target is a sponge. So thanks to the AIM spacecraft we’ll know exactly what this object is made from, and we can validate all the digital simulations of the impact, and better interpret the results of it,” says Patrick Michel.

What follows, it’s hoped, will be a whole raft of asteroid deflection missions, perfecting out technique so we’re ready when a true menace appears on the horizon.

“Asteroids are a genuine threat to consider, because even if we don’t have to worry in the short term, it’s the only threat from nature that we can predict, and against which we can do something.” concludes Patrick Michel.

‘Potentially hazardous’ asteroid 2000 EM26 to fly close to Earth

Space rock to pass by Earth 2.1m miles away, but astronomers say 270-metre object poses significant danger in case of impact

A “potentially hazardous” asteroid the size of three football fields will come uncomfortably close to Earth early on Tuesday.

The space rock, known as 2000 EM26, poses no threat and will pass the Earth at just under nine times the distance to the moon.

But it is defined as a potentially hazardous near-Earth object (NEO) large enough to cause significant damage in the event of an impact. Scientists estimate the asteroid, travelling at 27,000mph, is 270 metres (885ft) wide.

Continue Reading