Fascination with the sky has been an age old subject attracting human interest throughout mans existence on the planet. Movies have been produced, books have been written and it’s perhaps safe to assume curiosity and human thirst for knowledge will continue to drive a desire to make sense of the phenomenon above. While the desire to understand space is quite an honorable endeavor, a number of experts in the scientific community have sounded the alarm, sort of a wake up call in an attempt to focus attention to the dangers that asteroids in our solar system present. As a result, the warning has triggered a plan that seeks to launch an unmanned spacecraft on a collision course to collide into an Asteroid heading directly towards our planet.
So what exactly are these cosmic flying mountains called asteroids? And what do we know now about their orbital paths?
Asteroids are small, airless rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. In total, the mass of all the asteroids is less than that of Earth’s moon. But despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That’s one reason scientists study asteroids and are eager to learn more about their numbers, orbits and physical characteristics. If an asteroid is headed our way, we want to know that.
Most asteroids lie in a vast ring between the orbits of Mars and Jupiter. This main belt holds more than 200 asteroids larger than 60 miles (100 kilometers) in diameter. Scientists estimate the asteroid belt also contains more than 750,000 asteroids larger than three-fifths of a mile (1 kilometer) in diameter and millions of smaller ones. Not everything in the main belt is an asteroid — for instance, comets have recently been discovered there, and Ceres, once thought of only as an asteroid, is now also considered a dwarf planet.
Many asteroids lie outside the main belt. For instance, a number of asteroids called Trojans lie along Jupiter’s orbital path. Three groups — Atens, Amors, and Apollos — known as near-Earth asteroids, orbit in the inner solar system and sometimes cross the path of Mars and Earth.
Most asteroids, including Vesta, reside in the doughnut-like ring of the main asteroid belt that peppers the space between Mars and Jupiter. Other asteroids whirl in tight circles closer to the sun than the Earth, while a large number of them share planets’ orbits. Not all asteroids are so happy to stay put, though: Some asteroids’ orbits take them on planet-crossing swings through the inner solar system.
7 Asteroids in our Solar System
• The biggest asteroid by far is Ceres — which explains why it was discovered first — and it makes up about a third of the asteroid belt’s mass. The object is so hefty that it’s the only asteroid that has the gravitational strength to pull itself into a sphere.
• Baptistina is the name of one of the youngest families of asteroids in the asteroid belt. (Families of asteroids are swarms of objects that share orbital characteristics, and are often named after their most prominent member.) According to computer models, Baptistina and its swarm were spawned some 160 million years ago by a smashup between a 37-mile-wide body (60 kilometer) body and another object about 106 miles (170 kilometers) in diameter. That cataclysm created hundreds of large objects, some of which then drifted into a collision course with Earth.
• Hektor is very elongated, with length and width dimensions of approximately 230 by 124 miles (370 by 200 kilometers). Hektor has a moon as well. Unlike Kleopatra, however, Hektor is not found in the main asteroid belt; instead, the dark, reddish body dominates as the biggest of Trojan asteroids stuck in Jupiter’s orbit. These rocks lurk in what are known as the L4 and L5 Lagrangian points — two of the five zones in an orbit where the gravity of two bodies (in this case, Jupiter and the Sun) balances out. L4 and L5 lie ahead and behind, respectively of Jupiter.
• Many asteroids, believe it or not, have a moon, and some even sport two satellites. Kleopatra has two moons, which were named Alexhelios and Cleoselene earlier this year. To boot, the metallic asteroid has an unusual dog-bone shape. The asteroid is roughly 135 by 58 by 50 miles (217 by 94 by 81 kilometers) in length, height and width. Its moons Alexhelios and Cleoselene are, respectively, about 3 miles (5 kilometers) and 1.9 miles (3 kilometers) in diameter.
• In 2009, observations in infrared light confirmed the presence of this ice, as well as carbon-containing, or organic, molecules. These characteristics make the icy asteroid Themis and similar bodies called main belt comets good candidates for having delivered water and carbon — some of the ingredients of life — to the surface of a young, hot, dried-out Earth some four billion years ago.
• Celtic god, the asteroid Toutatis is one of the oddest space rocks. Instead of rotating in an orderly fashion about an axis, the double-lobed object chaotically tumbles. This unpredictable movement partially derives from Toutatis being composed of two bodies barely in contact with each other and from the influences of both Earth and Jupiter’s gravity.
• Toutatis has made some close shaves to Earth, and passed within 1,000,000 miles (1.61 million kilometers) of Earth, or about four Moon distances, back in 2004. Yet some rocks have made notably closer passes, and the one that has most alarmed astronomers and the public alike is Apophis. Discovered in 2004 and named after the Greek word for the evil Egyptian god of darkness, Apophis will return to the neighborhood in 2029. At the time, scientists calculated that its impacting Earth on that future pass were as high as 1 in 40, but subsequent measurements have now relegated that possibility to almost nil. Panic peaked in December 2004, and Apophis achieved a ranking of 4 on the Torino scale, the 10-point scale that rates the risk of an object colliding with Earth (10 being an unquestioned apocalypse). Although Apophis is now deemed zero for its 2029 pass, it will zoom a mere 18,600 miles (30,000 kilometers) above Earth’s surface.
Scientists in Europe and the United States are moving forward with plans to intentionally smash a spacecraft into a huge nearby asteroids in 2022 to see inside the space rock. European space officials are seeking ideas to help develop a mission to knock an asteroid off its course, in case one-day humans must pull off such a stunt to save Earth from a catastrophic space-rock collision.
The ambitious European-led Asteroid Impact and Deflection Assessment mission, or AIDA, is slated to launch in 2019 to send two spacecraft — one built by scientists in the U.S, and the other by the European Space Agency — on a three-year voyage to the asteroid Didymos and its companion. Didymos has no chance of impacting the Earth, which makes it a great target for this kind of mission; scientists involved in the mission said in a presentation Tuesday (March 19) here at the 44th annual Lunar and Planetary Science Conference.
This space rock system is actually a pair of asteroids, one smaller, one larger, that orbit each other as they zoom around the sun.
Didymos is actually a binary asteroid system consisting of two separate space rocks bound together by gravity. The main asteroid is enormous, measuring 2,625 feet (800 meters) across. It is orbited by a smaller asteroid about 490 feet (150 m).
Ultimately, scientists are interested in conducting tests that will guide unmanned spacecrafts into an asteroid at various speeds to measure response time and other variables that might exist in an atmosphere void of gravity’s influential pull. If these tests prove successful, the only foreseeable danger left will be how to detect smaller elements that have the potential of entering our atmosphere on a collision course.