What a long way we've come from the celestial police of the Victorian Era, to the discovery of over 10,000 NEAs at the beginning of 2014. Although there are many NEAs, some are more interesting than others. It takes more than the discovery moment to understand our distant neighbors. What is this new discovery? Is it a Near Earth Asteroids? A Potentially Hazardous Object? Is it in the Main Belt? Is it a Friend or Foe? Astra's Asteroid Catalog looks at some of the more interesting or promising NEAs.
Some asteroids have been observed more often then others. The really faint ones, like the 28- magnitude asteroid that the asteroid redirect mission is seeking to ensure Earth's safety, are often spotted. Once found, they are soon lost, but will they be seen again? Will they find their way to the bottom of the sea or burn up in the sun? How do we visualize the paths that these asteroids take and how will we influence those paths in the future?
Potentially Hazardous Asteroid (PHA)
An NEA is considered a Potentially Hazardous Asteroid (PHA) when its orbit comes within 0.05 AU (7.5 million km) of the Earth's orbit. This is referred to as the Earth Minimum Orbit Intersection Distance (MOID)The largest known PHA is 4179 Toutatis (1989 AC), 9 km in diameter.
Apophis 2004 MN4
One of the scariest asteroids of all time, Apophis was discovered on June 19, 2004 by astronomers at Kitt Peak Observatory. Apophis is an Aten asteroid that orbits the sun every 323.5 days. It has been officially observed over 4,000 times and in April 2013, the Aericibo radio telescope took additional measurements to rule out the possibility of a strike by Apophis in 2029.
Plymouth Rock 2008 EA9Plymouth Rock
The Plymouth Rock mission was proposed in 2009 by Lockheed Martin under the Constellation program back when NASA was following the Vision for Space Exploration. The concept required a "deep space" version of the Orion spacecraft capable of travelling over 10 million kilometers to a distant asteroid. At that time the newly discovered asteroid 2008 EA9 was proposed as a likely target.
The asteroid 2008 EA9 was hopefully dubbed, "Plymouth Rock", befitting a destination at a distant new world. Lockheed Martin put a lot of work into the design of the mission without outside financial support and it really is their mission. This mission was widely discussed and provides a very realistic look into the logistics and challenges of a human mission to the asteroids.
Lockheed Martin's Plymouth Rock mission - Presented at the SBAG meeting in November 2009.
This document contains a lot of interesting information and details on a human mission to the asteroids. Well worth examining because of the logistical information on a deep space mission to the rocks . . . er, stars.
2008 TC3 - From Discovery to Impact in 20.5 Hours
On the morning of October 6, 2008, a small asteroid was discovered by the Catalina Sky Survey. The preliminary calculation of the orbit of this asteroid showed that it was heading straight for planet Earth and that impact was eminent. Within an hour of the asteroid's discovery, JPL determined that the and found to be an impactor. It landed the Sudan less than 21 hours after its discovery on that October morning.The full story of Earth-impacting asteroid 2008 TC3
The discovery and prediction of an NEA impact tested the process and demonstrated the effectiveness of NASA's Near-Earth Object Program. After the discovery of 2008 TC3, 26 international observatories provided observational information that confirmed the orbit and impact. The impactor was estimated to be
Asteroid 2008 TC3 Strikes Earth: Predictions and Observations Agree - NASA's NEO program write up
3753 Cruithne3753 Cruithne
3753 Cruithne orbits in a bean-shaped orbit as viewd from the Earth. Its orbit describes a horseshoe that can transition into a quasi-satellite orbit.[t has been incorrectly called "Earth's second moon" but it does not orbit Earth.
2012 DA14 - Upstaged!
The world was awaiting a NEA close approach side show, but no. There was new kid in town! Asteroid 2012 DA14 & Chelyabinsk Impactor
1991 VG (Very Good)1991 VG
Is it an asteroid or a piece of space junk, like a Saturn rocket?This asteroid, or rather NEO was discovered in November 1991 by Jim Scotti using a Spacewatch telecope at Kitt Peak observatory. Shortly after discovery, it was seen to change brightness and it was thought that this might be a piece of early space hardware. Some even speculate that it is some kind of alien probe. In any case, it is very small, perhaps a mere 30-feet in diameter, making it difficult to observe. The next close passage is October 26, 2016 when Earth catches up with this elusive object.
Is this an NEA that we can capture and examine closely, or just some piece of space junk launched in an earlier epoch of human space flight?
2008 HU42008 HU4 - An article by Paul Gilster presents the case that this object might be artificial
Is it an asteroid or a piece of space junk, like a Saturn rocket? The next close approach of this NEA is 2016, to return again in 2026. This seems like a good opportunity to check it out to see if it is a sounc candidate for the Asteroid Redirect Mission.
Orpheus 1982 HR - Asteroid Dreams
It seems as though I (Astra a.k.a. Dawn Jenkins) have spent my entire life dreaming of travel to the moon, the solar system, and the stars beyond. Perhaps inspired by the astronomers scanning the skies for those unknown terrors from space, those potentially dangerous asteroids, as a young adult I dreamed of a planetary defense that protected us from that menace from space.
Even though planetary defense seemed a necessary activity, I also realized that those distant neighbors could be the source of great riches, if only we could explore them in detail and discover which ones held those hidden treasures. In 2000, I was asked to present my own vision for the future of space exploration, by the editors of the newsletter at NASA Glenn Research Center. I worked in an area that was building an orbitting laboratory that is currently in use on the International Space Station but I dreamed of exploring the solar system. So I wrote about a mission to a nearby asteroid.
After careful research, I settled on the Apollo asteroid, 3361 Orpheus (1982 HR) an NEA that was discovered on April 24, 1982 by Carlos Torres at the Cerro El Roble Astronomical Station. This asteroid has quite an eccentric orbit that carries it across the orbits of the Earth and Mars at times approaching our sister planet Venus as well. From late 2013 to early 2014, Orpheus "terrorizes" the inner solar system. But it was the close passage of November 21, 2021 that I chose for Dione Wilder, my mission commander, to dream of that spaceflight. This trip is attractive because there is another close passage in June of 2022.
3361 Orpheus 1982 HR
Discovery Date: April 24, 1982
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