This story updated Tuesday to correct the asteroid's distance to the Earth.


FORT IRWIN The NASA Goldstone Deep Space Communications Complex has been monitoring a rare asteroid one that will fly closer to the Earth than any other has in more than three decades.


The asteroid, 2005 YU55, is estimated to come closest to the Earth at 3:28 p.m. Tuesday, though it cannot be seen with the eye. Lance Benner is the principal research scientist of 2005 YU55. He said the asteroid will come as close as 215,100 miles from the Earth closer than the moon.


The Goldstone Complex has been taking radio images of the asteroid since Friday. Though the center has already been taking images of the object, Benner said Tuesday is when the Complex will get the strongest radar images.


2005 YU55 is about 1,300 feet wide, with an almost spherical shape, Benner said. After running tests, the Complex determined the asteroid is a C class asteroid and is a dark object as reflective as charcoal. Images already reveal the asteroid's craters and mountainous surface.


The images are captured by radar imaging. This involves directing radiowaves toward the asteroid and reading the waves that are bounced back off of the object. Goldstone engineers said their radio telescope is the only antenna in the world tracking the asteroid like this.


"It's an absolutely fascinating feat of engineering," said Robert Haroldsson, antenna and servo maintenance manager at Goldstone. "I've been here since 1983 and it still fascinates me to see the antenna work."


The asteroid rotates once every 18 hours. Continuous imaging during the rotation is necessary to get a full picture of how the asteroid looks, Benner said. The team will eventually use that data to create a three dimensional replica of the asteroid which will then be used to study the object's gravitational pull.


According to Benner, the asteroid is scheduled to move close to Earth again in 2075 and it could be closer at that time.


After the asteroid passes, Benner estimates the team of scientists will spend months going through and analyzing the data gathered during this close encounter.


Benner said understanding asteroids is essential to better understand the Earth and the history of the solar system, adding, "That's why it's so important that we keep monitoring these objects."