Comet Science
NASA, FEMA, International Partners Plan Asteroid Impact Exercise
Dwayne Brown / JoAnna Wendel
NASA Headquarters, Washington
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
While headlines routinely report on “close shaves” and “near-misses” when near-Earth objects (NEOs) such as asteroids or comets pass relatively close to Earth, the real work of preparing for the possibility of a NEO impact with Earth goes on mostly out of the public eye.
For more than 20 years, NASA and its international partners have been scanning the skies for NEOs, which are asteroids and comets that orbit the Sun and come within 30 million miles (50 million kilometers) of Earth’s orbit. International groups, such as NASA’s Planetary Defense Coordination Office (PDCO), the European Space Agency’s Space Situational Awareness-NEO Segment and the International Asteroid Warning Network (IAWN) have made better communication of the hazards posed by NEOs a top priority.
MedIa Event: NASA Invites Media to Learn More About Near-Earth Asteroids, Comets
April 25, 2019
MEDIA ADVISORY M19-034
Media are invited to hear experts from around the world discuss the latest research on near-Earth objects (NEOs) at the International Academy of Astronautics’ 2019 Planetary Defense Conference, Monday, April 29 through Friday, May 3 at The Hotel at the University of Maryland.
NEOs include asteroids and comets that orbit our Sun and come within 30 million miles of Earth’s orbit, where some may pose an impact hazard to our planet. NASA experts will talk about the agency’s first mission to demonstrate a technique to change the motion of an asteroid in space and other aspects of the nation’s planetary defense program.
The Many Faces of Rosetta’s Comet 67P
Markus Bauer
European Space Agency, Noordwijk, Netherlands
M. Ramy El-Maarry
University of Colorado
Matt Taylor
ESA Rosetta project scientist
NOTE: Make sure you check 0ut the accompanying Space Photo Exploration page for Comet 67P/Churyumov-Gerasimenko
Images returned from the European Space Agency’s Rosetta mission indicate that during its most recent trip through the inner solar system, the surface of comet 67P/Churyumov-Gerasimenko was a very active place – full of growing fractures, collapsing cliffs and massive rolling boulders. Moving material buried some features on the comet’s surface while exhuming others. A study on 67P’s changing surface was released Tuesday, March 21, in the journal Science.
“As comets approach the sun, they go into overdrive and exhibit spectacular changes on their surface,” said Ramy El-Maarry, study leader and a member of the U.S. Rosetta science team from the University of Colorado, Boulder. “This is something we were not able to really appreciate before the Rosetta mission, which gave us the chance to look at a comet in ultra-high resolution for more than two years.”
Halloween Skies to Include Dead Comet Flyby
The large space rock that will zip past Earth this Halloween is most likely a dead comet that, fittingly, bears an eerie resemblance to a skull.
Scientists observing asteroid 2015 TB145 with NASA’s Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun.
The belated comet has also been observed by optical and radar observatories around the world, providing even more data, including our first close-up views of its surface. Asteroid 2015 TB145 will safely fly by our planet at just under 1.3 lunar distances, or about 302,000 miles (486,000 kilometers), on Halloween (Oct. 31) at 1 p.m. EDT (10 a.m. PDT, 17:00 UTC).
The first radar images of the dead comet were generated by the National Science Foundation’s 305-meter (1,000-foot) Arecibo Observatory in Puerto Rico. The radar images from Arecibo indicate the object is spherical in shape and approximately 2,000 feet (600 meters) in diameter and completes a rotation about once every five hours.
“The IRTF data may indicate that the object might be a dead comet, but in the Arecibo images it appears to have donned a skull costume for its Halloween flyby,” said Kelly Fast, IRTF program scientist at NASA Headquarters and acting program manager for NASA’s NEO Observations Program.
Managed by the University of Hawaii for NASA, the IRTF’s 3-meter (10 foot) telescope collected infrared data on the object. The data may finally put to rest the debate over whether 2015 TB145, with its unusual orbit, is an asteroid or is of cometary origin.
“We found that the object reflects about six percent of the light it receives from the sun,” said Vishnu Reddy, a research scientist at the Planetary Science Institute, Tucson, Arizona. “That is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light. That suggests it could be cometary in origin — but as there is no coma evident, the conclusion is it is a dead comet.”
Radar images generated by the Arecibo team are available at:
Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University of Hawaii’s Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object Observations (NEOO) Program. The next time the asteroid will be in Earth’s neighborhood will be in September 2018, when it will make a distant pass at about 24 million miles (38 million kilometers), or about a quarter the distance between Earth and the sun.
Radar is a powerful technique for studying an asteroid’s size, shape, rotation, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than would be possible otherwise.
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 (NEOs). To date, U.S.-funded assets have discovered over 98 percent of the known NEOs.
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, often with grants, interagency transfers and other contracts from NASA, and also with international space agencies and institutions that are working to track and better understand these objects. In addition, NASA values the work of numerous highly skilled amateur astronomers, whose accurate observational data helps improve asteroid orbits after they are found.
NASA’s Jet Propulsion Laboratory, Pasadena, California, hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program within the agency’s Science Mission Directorate.
More information about asteroids and near-Earth objects is at these websites:
http://www.jpl.nasa.gov/asteroidwatch
Rosetta comet probe team narrows landing site to five locations
The European Space Agency’s Rosetta Comet mission has chosen five likely landing sites for its Philae’s lander on comet 67P/Churyumov-Gerasimenko. The lander is scheduled to descend down to the comet’s nucleus in November.
According to a press release by NASA’s Jet Propulsion Laboratory:
Rosetta is an international mission headed up by the ESA with support from NASA, and will be the first ever attempt to land on a comet.
Rosetta is an international mission headed up by the ESA with support from NASA, including providing instruments.
Due to the distance from Earth and the orbiter and lander creates uncertainties in navigating the orbiter close to the comet, the only way possible to pick a landing site in terms of an ellipse, which will cover up to six-tenths of a square mile (or one square kilometer) where the Philae lander might land.
“This is the first time landing sites on a comet have been considered,” said Stephan Ulamec, Philae Lander Manager at the German Aerospace Center, Cologne, Germany in a press release.
Will the lander be able to maintain regular communications with Rosetta?
Is there sufficient illumination for scientific operations and enough sunlight to recharge the lander’s batteries beyond its initial 64-hour lifetime without causing overheating?
The team reduced the number of landing sites from 10 to five, and gave them letters that have no special meanings.
“The process of selecting a landing site is extremely complex and dynamic; as we get closer to the comet, we will see more and more details, which will influence the final decision on where and when we can land,” said Fred Jansen, Rosetta’s mission manager from the European Space Agency’s Science and Technology Centre in Noordwijk, The Netherlands, in the same press release.
During the time the team is preparing their analysis, Rosetta will move to 31 miles (50 kilometers) of the comet allowing more detailed study of the five landing sites.
The ESA Rosetta team plans to land the Philae lander sometime around mid-November when the comet will be about 280 million miles (450 million Kilometers). This means the comet will be three times the distance than the Earth is to the Sun (280 million miles also equals 3 astronomical units, where an astronomical unit is 93 million miles, or the distance between the Sun and the Earth).
At 3 AU, there should be little to no activity on the comet that would jeopardize the landing of the Philae lander on the comet’s surface, and just before the comet becomes active.
Launched in March 2004, Rosetta was reactivated in January 2014 after a record 957 days in hibernation. Composed of an orbiter and lander, Rosetta’s objectives since arriving at comet 67P/Churyumov-Gerasimenko earlier this month are to study the celestial object up close in unprecedented detail, prepare for landing a probe on the comet’s nucleus in November, and track its changes through 2015, as it sweeps past the sun.
Cosmologists consider comets as time capsules containing materials left over from building of the Solar System 3.4 billion years ago. Rosetta’s lander will obtain the very first images taken from a comet’s primordial composition by drilling into the surface.
According to the press release:
Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta’s Philae lander is provided by a consortium led by the German Aerospace Center, Cologne; Max Planck Institute for Solar System Research, Gottingen; French National Space Agency, Paris; and the Italian Space Agency, Rome. NASA’s Jet Propulsion Laboratory in Pasadena, California, a division of the California Institute of Technology, manages the U.S. participation in the Rosetta mission for NASA’s Science Mission Directorate in Washington.
For Specifications on: 67P/Churyumov-Gerasimenko
