Samstag, 15. Juni 2013 - 16:35 Uhr
On May 31, 2013, asteroid 1998 QE2 will sail serenely past Earth, getting no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. And while QE2 is not of much interest to those astronomers and scientists on the lookout for hazardous asteroids, it is of interest to those who dabble in radar astronomy and have a 230-foot (70-meter) -- or larger -- radar telescope at their disposal.
"Asteroid 1998 QE2 will be an outstanding radar imaging target at Goldstone and Arecibo and we expect to obtain a series of high-resolution images that could reveal a wealth of surface features," said radar astronomer Lance Benner, the principal investigator for the Goldstone radar observations from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid's distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise."
The closest approach of the asteroid occurs on May 31 at 1:59 p.m. Pacific (4:59 p.m. Eastern / 20:59 UTC). This is the closest approach the asteroid will make to Earth for at least the next two centuries. Asteroid 1998 QE2 was discovered on Aug. 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, New Mexico.
The asteroid, which is believed to be about 1.7 miles (2.7 kilometers) or nine Queen Elizabeth 2 ship-lengths in size, is not named after that 12-decked, transatlantic-crossing flagship for the Cunard Line. Instead, the name is assigned by the NASA-supported Minor Planet Center in Cambridge, Mass., which gives each newly discovered asteroid a provisional designation starting with the year of first detection, along with an alphanumeric code indicating the half-month it was discovered, and the sequence within that half-month.
Radar images from the Goldstone antenna could resolve features on the asteroid as small as 12 feet (3.75 meters) across, even from 4 million miles away.
"It is tremendously exciting to see detailed images of this asteroid for the first time," said Benner. "With radar we can transform an object from a point of light into a small world with its own unique set of characteristics. In a real sense, radar imaging of near-Earth asteroids is a fundamental form of exploring a whole class of solar system objects."
Asteroids, which are always exposed to the sun, can be shaped like almost anything under it. Those previously imaged by radar and spacecraft have looked like dog bones, bowling pins, spheroids, diamonds, muffins, and potatoes. To find out what 1998 QE2 looks like, stay tuned. Between May 30 and June 9, radar astronomers using NASA's 230-foot-wide (70 meter) Deep Space Network antenna at Goldstone, Calif., and the Arecibo Observatory in Puerto Rico, are planning an extensive campaign of observations. The two telescopes have complementary imaging capabilities that will enable astronomers to learn as much as possible about the asteroid during its brief visit near Earth.
NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the U.S. has the most robust and productive survey and detection program for discovering near-Earth objects. To date, U.S. assets have discovered over 98 percent of the known NEOs.
In 2012, the NEO budget was increased from $6 million to $20 million. Literally dozens of people are involved with some aspect of near-Earth object (NEO) research across NASA and its centers. Moreover, there are many more people involved in researching and understanding the nature of asteroids and comets, including those that come close to the Earth, plus those who are trying to find and track them in the first place.
In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country that are working to track and better understand these objects, often with grants, interagency transfers and other contracts from NASA.
NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study, and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.
In 2016, NASA will launch a robotic probe to one of the most potentially hazardous of the known NEOs. The OSIRIS-REx mission to asteroid (101955) Bennu will be a pathfinder for future spacecraft designed to perform reconnaissance on any newly-discovered threatening objects. Aside from monitoring potential threats, the study of asteroids and comets enables a valuable opportunity to learn more about the origins of our solar system, the source of water on Earth, and even the origin of organic molecules that lead to the development of life.
NASA recently announced developing a first-ever mission to identify, capture and relocate an asteroid for human exploration. Using game-changing technologies advanced by the Administration, this mission would mark an unprecedented technological achievement that raises the bar of what humans can do in space. Capturing and redirecting an asteroid will integrate the best of NASA's science, technology and human exploration capabilities and draw on the innovation of America's brightest scientists and engineers.
Astronomers are gearing up to watch a giant asteroid sail past the Earth this week. It is nine times as long as a cruise liner and dubbed 1998 QE2, but this chunk of space rock has nothing to do with the famous Cunard vessel now docked in Dubai.
The asteroid will come to a distance of 5.8 million km (3.6 million miles) - closer than at any time in the next two centuries but still a reasonably wide berth with no danger of an impact. The flyby will give telescopes around the world the chance to study what is logged as a Potentially Hazardous Object.
Closest approach will occur on May 31 when the asteroid will be about 15 times the distance of the Moon. That will bring it near enough for powerful radio telescopes at Goldstone in California and Arecibo in Puerto Rico to bounce beams off it to make detailed radar maps of its surface.
1998 QE2, which was discovered by Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) robotic survey operating near Socorro, New Mexico, on August 19, 1998, will be in range for Goldstone’s 70 meter (230 ft) steerable dish from May 28 as it heads north through the sky. The observatory has scheduled observations on seven dates from May 30 to June 9.
The 305 meter (1,000 ft) Arecibo dish, which sits fixed in a well in the ground, will be able to observe from June 5, and observations have been planned from June 6 to 12. Together the telescopes hope to pick out detail on the asteroid as small as 7.5 meters across.
On a previous flight through the neighbourhood in 2010, the asteroid was observed by NASA’s Spitzer Space Telescope which estimated it to be about 2.7 km in diameter. It is a member of the Amor class of asteroids which originated in the main belt between Mars and Jupiter. On of the largest members of this class is Eros which was visited by NASA’s NEAR Shoemaker probe in 2000.
1998 QE2 has a very low albedo, meaning it is a dark object and in fact its surface is as reflective as soot. It will still be visible in larger amateur telescopes, shining at magnitude 11 in early June.
Goldstone is operated by NASA’s Jet Propulsion Laboratory in California. Radar astronomer Lance Benner, principal investigator for the observatory, said: “Asteroid 1998 QE2 will be an outstanding radar imaging target at Goldstone and Arecibo and we expect to obtain a series of high-resolution images that could reveal a wealth of surface features.
“Whenever an asteroid approaches this closely, it provides an important scientific opportunity to study it in detail to understand its size, shape, rotation, surface features, and what they can tell us about its origin. We will also use new radar measurements of the asteroid’s distance and velocity to improve our calculation of its orbit and compute its motion farther into the future than we could otherwise.”
Last year NASA was given an increased budget to find and track the hundreds of asteroids known as Near Earth Objects that could potentially hit our planet causing devastation.
In 2016, NASA’s robotic OSIRIS-REx mission will be launched to asteroid (101955) Bennu. The study will help prepare for the threats close passing asteroids pose but also help scientists learn more about some of the earliest material formed in the Solar System.
NASA is also developing a mission to capture a small asteroid and bring it into orbit around the Moon so that astronauts can later visit it.
Asteroid hat einen Mond
A large asteroid that will sail relatively close past Earth on Friday is not alone. Radar images taken by astronomers on Wednesday revealed the asteroid, known as 1998 QE2, is accompanied by an orbiting moon.
“It was quite a surprise,” Marina Brozovic, a radar scientist with NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said during an NASA interview.
“This is something we did not expect,” she said.
The pair will come as close as about 3.6 million miles to Earth at 4:59 p.m. EDT on Friday. That’s just 15 times farther away than Earth’s moon.
“For an asteroid of this size, it’s a close shave,” said Paul Chodas with NASA’s Near Earth Object program office at JPL.
Measuring about 1.7 miles in diameter, 1998 QE2 is among the largest asteroids with orbits that can pass near Earth.
At its most distant, 1998 QE2 flies to the far edge of the Main Asteroid Belt, nearly to Jupiter. Its pass on Friday is expected to be its closest approach to Earth for at least the next 200 years.
“For the foreseeable future, there’s nothing to worry about,” Chodas said.
Asteroid 1998 QE2 was not named after the United Kingdom’s Queen Elizabeth II, or the QE2 cruise ship. The designation stems from the date and place of its discovery – 1998 by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program.
Astronomers are hoping to get images and data during the flyby that rival what a visiting spacecraft could collect.
Image: A series of radar images by NASA’s Goldstone Observatory of asteroid 1998 QE2 and moon. Credit: NASA
The closest approach of the asteroid occurred today at 4:59 p.m. EDT, when the asteroid was no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon.
Its next pass, on July 12, 2028 will be at a very safe 45 million miles (73 mil km).
Arecibo Radar Sees Asteroid 1998 QE2 and Moon
Arecibo, Puerto Rico, June 14, 2013 - Arecibo Observatory catches the most detailed radar images ever of asteroid 1998 QE2 and its newly discovered moon as they safely pass our planet.
Arecibo Observatory continues to take radar images of asteroid 1998 QE2 and its moon as the space rock sails safely passed earth this week. The images show a dark cratered asteroid 3 kilometers across (1.9 miles) with a companion moon 750 meters (2,500 feet) in size. The asteroid and its moon passed 6 million kilometers (3.75 million miles) from earth, far enough from our planet not to worry, close enough to study this rocky world with the most sensitive radar telescope in the world, the U.S. National Science Foundation's Arecibo Observatory in Puerto Rico. "Asteroid QE2 has no chance of hitting earth," said USRA's Dr. Michael Nolan, head of the asteroid radar group at Arecibo Observatory who took the images.
Images: Radar images of Asteroid 1998 QE2 taken on June 7, 2013 as the asteroid and its moon safely passed Earth. The asteroid appears lit from the bottom while we The light is from the powerful radio waves from the radar transmitter. The Earth is at the bottom of this image: the "side view" is a result of the radar imaging method. Several craters are visible on the asteroid, and the moon appears as a bright streak. Each pixel is 7.5 meters (25 feet). Image credit: Arecibo Observatory/NASA/Ellen Howell
Arecibo Observatory and the complementary Goldstone Solar System Radar in California run by NASA's Jet Propulsion Laboratory are unique among telescopes on earth for their ability to resolve features on asteroids, when optical telescopes on the ground would see these rocks as simple points of light. "We transmit powerful radio waves at passing asteroids," said Nolan. "Arecibo is a thousand times more powerful than your microwave oven." Sensitive radio receivers collect radio signals reflected from the asteroids and computers turn the radio echoes into images that show features such as craters and the smaller moon. The moon appears brighter than the asteroid as it is rotating more slowly; thus, its Doppler echoes compress along the Doppler axis of the image and appear stronger.
Of the asteroids that come close to Earth, approximately one out of six have moons. Dr. Patrick Taylor, a USRA research astronomer at Arecibo, remarked that "QE2's moon is roughly one-quarter the size of the main asteroid," which is a lumpy, battered world in the inner part of our solar system. "Similarly, our moon is also approximately one-fourth the size of our planet."
QE2's moon will help scientists determine the mass of the main asteroid and what minerals make up the asteroid-moon system. "Being able to determine its mass from the moon helps us understand better the asteroid's material," said Dr. Ellen Howell, a USRA research astronomer at Arecibo Observatory who took both radar images of the asteroid at Arecibo and optical and infrared images using the Infrared Telescope Facility in Hawaii. While the optical images do not show detail of the asteroid's surface, like the radar images do, instead they allow for measurements of what it is made of. Howell said, "What makes this asteroid so interesting, aside from being an excellent target for radar imaging, is the color and small moon."
"Asteroid QE2 is dark, red, and primitive - that is, it hasn't been heated or melted as much as other asteroids," continued Howell. "QE2 is nothing like any asteroid we've visited with a spacecraft, or plan to, or that we have meteorites from. It's an entirely new beast in the menagerie of asteroids near Earth."
The provisional designation "1998 QE2" reflects the mid-August 1998 discovery date of this asteroid and is not related to the Queen Elizabeth II ocean liner, though a similarity of the asteroid's name to that of a cruise ship makes for interesting size comparisons. Arecibo astronomer Rhys Taylor said, "The moon is twice the length of the Queen Elizabeth II ocean liner, while the asteroid is nine times the length. Twenty-nine QE2 ships would fit around the circumference of asteroid QE2, plus or minus a ship."
USRA's Michael Nolan led the radar observations of QE2, with Ellen Howell, Patrick Taylor, Alessondra Springmann, Sean Marshall of Cornell University, and Mariah Law of Embry-Riddle Aeronautical University, in collaboration with the Near-Earth Object radar team at NASA/JPL and Goldstone Observatory in California. Observations continued through the morning of June 13, 2013.
Located in Puerto Rico, the Arecibo Observatory is home to the world's largest and most sensitive single-dish radio telescope, and dedicates hundreds of hours a year of its telescope time to improving our knowledge of near-Earth asteroids.
About Arecibo Observatory
The Arecibo Observatory is operated by SRI International in alliance with Ana G. Méndez-Universidad Metropolitana and the Universities Space Research Association, under a cooperative agreement with the National Science Foundation (AST-1100968). The Arecibo Planetary Radar program is supported by NASA's Near Earth Object Observation program. The Arecibo Observatory is sponsored by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Universities Space Research Association (USRA) is an independent, nonprofit research corporation where the combined efforts of in-house talent and university-based expertise merge to advance space science and technology. USRA works across disciplines including biomedicine, astrophysics, and engineering and integrates those competencies into applications ranging from fundamental research to facility management and operations. USRA engages the creativity and authoritative expertise of the research community to develop and deliver sophisticated, forward-looking solutions to Federal agencies and other customers - on schedule and within budget.