NASA’s Asteroid Redirect Mission (ARM) scheduled in the mid -2020s has yet to determine which asteroid they plan to go out and corral into the orbit of our moon. The work is still ongoing to determine the winning asteroid candidate. So far, NASA has narrowed the selection down to the following three candidates: Itokawa, Bennu and 2008 EV5. It is possible, however, other asteroids could be added to this short list and these current favorites could be eliminated. The gringa feels like it’s a bad scene from a science fiction Bachelor episode.
Since NASA announced its asteroid initiative to the public three years ago, science experts as well as science enthusiasts from all over the world have collaborated in identifying these Big Bang rock leftovers throughout the cosmos. These efforts have been so successful, detection of near-Earth asteroids (NEOs) has increased by sixty-five percent.
On December 29, 2010, the Japanese Aerospace Exploration Agency’s (JAEA) spacecraft “Hayabusa” returned to Earth with samples from an asteroid they named “Itokawa”. The Japanese led international crew of scientists brought back a chunk of an alien world. Hayabusa traveled one billion kilometers for over two years to execute what must be the world’s longest pick-up and delivery service ever. The gringa would not want to pick up the tab for that tip! Five bucks for the pizza guy is my absolute limit! This successful joint mission of multiple nations led by the Japanese was successful in bringing scientists dust particles from another world, the third such achievement the world has ever seen.
Images of Itokawa were taken when the asteroid crossed near Earth in 2005. It’s surface is unique to any others that have been observed because it seems to have no craters. The scientists are really scratching their heads over this little mystery. One hypothesis thinks it’s possible that craters simply cannot form on Itokawa because rather than being a solid rock asteroid, it actually is a junk pile of multiple space rocks and ice chunks held together by gravity. If it gets struck by a meteor, it would just jiggle around. The gringa’s not so sure she holds with this theory, but, hey, I’m not scientist. Who am I to criticize. The asteroid holds other novelties as well. One part of its interior is denser than the other. For the gringa, that sounds like people. The experts will continue their studies and, maybe one day, the world will know the answer to why Itokawa has a hard spot and no pock marks. It almost sounds like a disease.
Another asteroid favorite is Bennu. This little fella seems to have led a hard life. Researchers believe old Bennu (billions of years old) was dismembered by the gravity of multiple planets. Now THAT’S what the gringa calls living in a rough neighborhood. NASA’s Goddard Space Flight Center in Greenbelt, Maryland has produced an animated video to introduce Bennu. It can be viewed here, on NASA’s website, or on YouTube.
In late 2016 a mission to Bennu is planned to launch. It should take about seven years for samples to be retrieved and then returned to Earth. Scientists suspect that Bennu is made up of chondrules. These are grains of mineral (in other words, space sand) that are held together by gravity and stationary electrical charges to form a solid rock. Scientist want to test their theory by getting their hands on some samples.
Bennu is important because it is like a time capsule which has preserved itself since the Big Bang that gave birth to it. It has not experienced geologic and chemical changes like our Earth. Bennu could possibly be a pristine example of the most primitive material in the entire solar system. This could help the scientific community understand how life began if organic material is present on Bennu that could have the building blocks of terrestrial life, such as carbon and hydrogen.
Bennu is not as dense as a regular Earth rock so it could possibly be hollow. It could be just another pile of rubble like Itokawa. It is also very dark, like asphalt. Because of this, it absorbs lots of sunlight which then creates a radiating effect which causes a reaction a bit like propulsion which affects its orbit. This is known as the Yarkovsky effect. So, basically, Bennu just kind of wanders the galaxy willy-nilly and why it has sometimes had close encounters with Saturn, Venus and Earth. The theory of being a rubble pile then explains why it seems to change shape because, when having a close call with a large planet, the gravitational effect would pull it apart and reshape it.
Now, NASA may call a Bennu encounter a “close call”, but the gringa’s not too worried. There is only a 1 in 2,500 chance that it could impact the Earth in our lifetime. We’ve got plenty of time to develop a planetary defense system that can give Bennu a little poke in the eye if he gets too close and send him on his way again.
The third contender for the asteroid lasso rodeo is asteroid 2008 EV5. Not a very romantic name. The gringa thinks the experts could have come up with something a bit more catchy. March 4, 2008 (big surprise there), the Mount Lemmon Survey in Tucson, Arizona discovered 2008 EV5. This asteroid has an interesting prominent ridge that parallels the rock’s equator, broken only be a depression 150 meters in diameter which is probably an impact crater. The surface seems to be very rocky so, once again, probably a junk heap asteroid made up of carbonaceous chondrite. It could be Bennu’s evil twin.
The gringa has discovered that at this time, 2008 EV5 is the favorite because it seems to be filled with “cobbles” or stones that meet the dimensions best suited for the ARM robotic retrieval system. I am so disappointed that what may be the most important asteroid of my lifetime will not have a clever or catchy name like Itokawa or Bennu. The world will know the final decision sometime in 2019. The gringa is crossing her fingers for an asteroid with a really cool name, like Gringa2015. A girl can dream, right?!
Sources and Photo Credit: www.nasa.gov