Earth's moon isn't exactly known for its
welcoming atmosphere, and its nights are especially bad.
A full lunar night lasts about 14 Earth days, during which temperatures
can drop as low as -180 degrees Celsius. Although most exploration drones are designed to handle extreme conditions and low temperatures, night upon the planetoid is apparently a little too extreme, wreaking havoc on a machine's delicate computer and electronic subsystems.
Scientists in China think they may have developed a robot capable of surviving these sub-zero conditions, and this week the Yutu Rover along with the Chang'e-3 lander prepared to endure the long night...by hibernating. The Yutu Rover went to sleep at 5:23 AM Beijing time on December 26, while the Chang'e-3 Lander clocked out a little earlier; 11:00 AM on Christmas Day. This isn't the first time the two machines have gone into an induced slumber - but it is the most hazardous.
The launch of the Yutu Rover was something of a flagship occasion, and not just for China. Yutu's trek to the moon marks the first lunar surface visit in nearly four decades, with the last trip made by the Soviet Union's Luna 24 sample return vehicle on December 14, 1972. Shortly after landing, the two beamed back a number of portraits taken of one another, before entering into a four-day induced hibernation state to avoid damage from direct solar radiation, which threatened significant heat damage.
"The break had been planned to last until December 23, but the scientists decided to restart Yutu for more research time, based on recent observations and telemetry parameters," explained Chinese Lunar Program Spokesman Pei Zhaoyu.
Yutu- a name which roughly translates to "Jade Rabbit" - isn't just on the lunar surface to snap a few pretty photographs, however. The actual purpose of the expedition is to probe the moon for natural resources which could potentially be used by future Chinese astronauts. The length of this expedition meant that both the Rover and the Lander needed to be capable of enduring temperatures well below sub-zero without suffering any permanent or debilitating damage.
According to the Xinhua State News Agency, engineers completed a series of tests on the probes to ensure they could withstand the temperatures, equipping both probes with a radioisotopic heat source in order to safeguard their internal equipment - all of which is situated in a warmed box belowdecks which will be maintained at a minimum temperature of 40 degrees Celsius. Of course, tests on Earth can only go so far - the only way we'll know for certain that the two probes are capable of surviving two weeks in the deep freeze is if they successfully reactivate when the night comes to an end.
Yutu will reawaken - along with Chang'e-3 - on January 12, 2014; at which point it will depart the landing zone forever, roaming the moon's surface for investigations expected to last a total of three months or more. Using a suite of onboard scientific instruments, Yutu will survey both the geological structure and composition of the moon in its search for resources- resources which may one day be used to establish a Chinese colony on the moon's surface in as little as a decade or two.
In other words, a hibernating robot is really just the tip of the iceberg here.