On the night of Sept 27th and the early morning hours of Sept 28th, a lunar eclipse will be visible for a large portion of the world. This weekend’s lunar eclipse is extra special because it occurs while the Moon is at its closest approach to Earth. Technically, it’s called the perigee-syzygy of the Earth-Moon-Sun system. But we all know it by another term – ‘supermoon.’
All the headlines are focusing on what the lunar eclipse will look like to us. But, what about around the moon. NASA touches on what the Lunar Reconnaissance Orbiter (LRO) team is doing as they prepare for the Earth to blot out the sun.
First, we need to understand what happens during around the moon during a lunar eclipse. Temperatures plummet rapidly as the Moon enters Earth’s shadow – nearly 280 degrees in a matter of minutes.
The LRO team does have experience when dealing with lunar eclipses. “We have a method and it works well,” says science operations planner Dawn Myers. “It’s always stressful during the approach of the eclipse, but we follow the same procedures every time and we haven’t had any trouble.”
These procedures include shutting down LRO’s instruments one by one. Science operations personnel at NASA’s Goddard Space Flight Center in Maryland will monitor the spacecraft before the lunar eclipse and the day after as they bring the instruments back online.
Not every instrument will be turned off during this lunar eclipse. A star track and heaters will be left on for improved navigation. An instrument called Diviner will also be left on. Diviner is a radiometer that measures the reflected energy off the surface of the moon and infrared emissions that indicate the temperature at the surface.
Diviner temperature measurements
During the LRO’s original two-year mission, the team powered down pretty much everything during lunar eclipses. But with the LRO in its sixth year, the team is taking more risks.
“Our power engineer looked at past eclipses and evaluated whether it would be feasible for us to leave an instrument on,” Myers said. “He told us if the voltage drops below a certain level, we would have to shut the instrument off, but that hasn’t happened yet.”
LRO deputy project scientist Noah Petro explains what Diviner will be observing during the lunar eclipse. “The rapid cooling of the surface during an eclipse gives us a view of how the top few centimeters cool differently than during a normal lunar night,” Petro said. “From this we learn about the size of particles at the surface.”
This month’s lunar eclipse will give LRO a “very unique set of measurements.” The LRO will pass over the moon’s surface at local noon time when the surface is at its warmest. That means Diviner will observe temperatures from one extreme to another.
It’s all about gathering as much data as possible. Petro says every lunar eclipse gives scientists more questions than answers. But without the data, scientists will never be able to answer them.
NASA will live stream the lunar eclipse
If the weather doesn’t cooperate on Sept. 27, check out NASA’s live stream of the lunar eclipse. NASA solar physicist Mitzi Adams will be on hand to talk about the eclipse and answer any questions you may have.
The live stream will start at 8:00 p.m. EDT and last until at least 11:30 p.m EDT. The total eclipse will start at the Marshall Space Flight Center in Huntsville, Alabama at 10:11 p.m. EDT and peak at 10:47 p.m. EDT.