NASA Headquarters

NASA is on the hunt to add potential candidate target asteroids for the agencys Asteroid Redirect Mission (ARM). The robotic mission will identify, capture and redirect a near-Earth asteroid to a stable orbit around the moon. In the 2020s, astronauts will explore the asteroid and return to Earth with samples. This will test and advance new technologies and spaceflight experience needed to take humans to Mars in the 2030s.

NASA has two options for robotic asteroid capture. One concept would capture a small asteroid in its native orbit the natural orbit in which it is found. The other would retrieve a boulder from a larger asteroid. NASA will decide between the capture options in December and hold a Mission Concept Review in early 2015, which will further refine the design of the mission.

A lean, agile team of NASA engineers are testing the two concepts, capitalizing on technology and engineering work already underway at NASA. Four industry teams selected through NASAs recent Broad Agency Announcement also are developing concepts to either enhance this work or provide alternative ideas.

NASAs plans to announce the target asteroid for the mission approximately a year before launching the robotic spacecraft, scheduled for no earlier than 2019. To date NASA has identified three valid candidates for the small asteroid concept and three for the boulder concept. The agency expects to identify one or two additional candidates each year that could become valid targets for the mission.

Before an asteroid can make the valid candidate list, NASAs ARM target identification criteria must be met. Scientists must determine the rotation, shape, precise orbit, spectral class, and most importantly, size of the asteroid itself. With the asteroid millions of miles away from Earth, defining these factors requires a series of observations and analysis.

Telescopes on Earth and in space contribute to the observation, tracking and characterization of an asteroid. The process begins by detecting Near Earth Objects (NEOs) and starting to track their orbits. Ground observatories first scan an area in the sky to detect an object moving across the background of stationary stars and report its position in relation to them. The International Astronomical Union Minor Planet Center collects the resulting data and determines if the object has already been identified. If classified as a new object, scientists will be able to have a rough orbit and estimate of the size of the object within a day or two of the initial discovery.

Detecting an asteroid isnt enough to conclude it could be a good candidate for NASAs asteroid mission. Scientists need to further understand an asteroids shape, size, spin rate, and even surface features when picking a candidate. The best way to precisely measure these characteristics is with interplanetary radar, but only if the object is close enough to Earth to be observed this way. When the asteroid is not within the range of radar, the NASAs Spitzer Space Telescope can contribute to the data collection using infrared imaging if the object can be seen by it.

Infrared light is a better indicator of an objects true size because by measuring its infrared glow the amount of solar heating the entire object re-radiates can be determined. Combining the data collected by Spitzer and ground observatories allows an asteroids density and mass to be more precisely estimated. Spitzers infrared imaging has enabled NASA to determine the size of two ARM candidates thus far.

The three valid candidates so far for the small asteroid concept are 2009 BD, 2011 MD and 2013 EC20. The size of 2009 BD is estimated to be roughly 4 meters (13 feet) in size, while 2011 MD is estimated to be approximately 6 meters (20 feet). These sizes are inferred by data provided by the Spitzer observatory. 2013 EC20 is about 2 meters (7 feet) in size, as determined by radar imaging.

Continue reading here:

NASA Identifying Candidate Asteroids For Redirect Mission