April 8, 2014
NASA Lunar Reconnaissance Orbiter Prepped For Upcoming Eclipse
[ Watch the Video: A Lunar Eclipse And The LRO ]
Brett Smith for redOrbit.com - Your Universe Online
While the eclipse is something to look forward to for late-night amateur astronomers, the upcoming celestial event will be a bit of a complication for NASA scientists in charge of the Lunar Reconnaissance Orbiter (LRO), which is currently studying the moon while in lunar orbit.
A total lunar eclipse occurs when the Earth, moon and sun are in perfect alignment, with the Earth blocking sunlight from reaching the moon. The batteries on board the LRO need sunlight to charge and since the eclipse will plunge the craft into an extended period of darkness – the LRO will have to go without recharging longer than usual.
"The spacecraft will be going straight from the moon's shadow to the Earth's shadow while it orbits during the eclipse," said Noah Petro, deputy project scientist for the LRO project at NASA's Goddard Space Flight Center in Greenbelt, Md.
While the LRO has orbited the moon during an eclipse before, past events have lasted for shorter periods of time. On April 15, the LRO will pass through Earth’s shadow twice before the eclipse ends. Petro said he expects the craft to make it through the entire event without a problem.
"We're taking precautions to make sure everything is fine," Petro said. "We're turning off the instruments and will monitor the spacecraft every few hours when it's visible from Earth."
[ Watch the Video: Understanding Lunar Eclipses ]
This eclipse will not allow for the LRO to remain in operation, but other eclipses may and the NASA team uses these events to study how the Moon cools while in the Earth’s shadow.
"For quite a while, people in LRO have been analyzing what's going to happen during this eclipse," Petro said. "We'll make sure the world knows LRO survived with no problems."
The upcoming eclipse is expected to peak around 3:45 a.m. EST. At this point in time, the Moon will be in the full shadow of the Earth, called the umbra, and appear dark red – the result of Earth’s atmosphere scattering the Sun’s visible light onto the surface of the Moon.
"It's a projection of all the Earth's sunsets and sunrises onto the moon," Petro said. "It's a very subtle effect, and if any part of the moon is illuminated in the sun, you can't really see it."
The April 15 eclipse is also the first of four total eclipses expected to occur over the next year-and-a-half at two-month intervals – a phenomenon known as a tetrad. Lunar eclipses occur in a seemingly random order – making a tetrad a fairly rare occurrence over the course of thousands of years. The April 15th eclipse is followed by another eclipse on Oct. 8, 2014, and another on April 4, 2015, and another on Sept. 28 2015.
“During the 21st century, there are 9 sets of tetrads, so I would describe tetrads as a frequent occurrence in the current pattern of lunar eclipses,” said NASA eclipse expert Fred Espenak. “But this has not always been the case. During the three hundred year interval from 1600 to 1900, for instance, there were no tetrads at all.”