Chang'e 5 Mission To Grab 4.4 lbs. of the Moon and Hurry Home

Chang'e 5 launches atop a Long March 5 rocket on Monday, Nov. 23. CNSA 

Earlier this week China launched its ambitious Chang'e 5 probe on a 23-day mission to the moon to collect and return lunar samples. Named for the Chinese moon goddess, it would be that country's first sample return mission and the first moon rocks brought back to Earth since 1976, when the Soviet Union's Luna 24 sent back a third of a pound (170 grams) from the Sea of Crisis (Mare Crisium).

The China National Space Administration (CNSA) hasn't released a detailed timeline, but we know that the spacecraft is expected to enter lunar orbit on November 27 shortly after the sun rises on its target, the region surrounding Mons Rümker (Mt. Rümker). The lander will descend to the sampling site in the following few days and collect 4.4 pounds (2 kilograms) of rocks, both from the surface and up to 6 feet (2 meters) underground. The lander will use a drill to unearth (unmoon?) these deeper specimens.  

This diagram lays out the different units of the Chang'e 5 spacecraft. The gray panels on either side of the lander are solar panels to produce electricity. Cwek / CC BY-SA 4.0

The Chang'e 5 lander also will analyze the composition of the lunar soil and use its ground-penetrating radar to study subsurface rocks. A panoramic camera will capture scenes. Once the samples are gathered they'll be placed inside an ascent vehicle which will return to lunar orbit and dock with an orbiter, where they'll be transferred to a special capsule for delivery to Earth. The capsule will land in Inner Mongolia around Dec. 16 and hurried off to the lab.

Mons Rümker is a massive volcanic complex of multiple lunar domes. NASA / LRO

Mons Rümker is a fascinating place. Despite the name it's not a mountain but a 40-mile-wide complex of at least two dozen lunar domes — low, rounded bulges that look like blisters. Domes are shield volcanoes that formed when lava erupted from cracks in the crust that tapped magma-rich chambers below. Some have summit craterlets, where the molten rock brimmed and spilled downslope. Domes are typically about a thousand feet (several hundred meters) high and 5 to 7.5 miles (8-12 km) across. 

The Hortensius dome field near Copernicus Crater is home to some of the most striking lunar domes. Several have crater pits at their summits. NASA / LRO

Although quiet now, Rümker has been a center of volcanic activity at various times in the moon's history. Measurements from orbit have detected basaltic (volcanic) rock there similar to basalts found on Earth. Some of the material in and around the formation may have formed as recently as 1.2 billion years ago. The rocks gathered by the Apollo astronauts were much older — between 3.1 and 4.4 billion years old. 

The Chinese mission hopes to collect some of these relatively young samples to expand our understanding of lunar chronology — what happened when in the long history of the moon. They'll do this by dating the specimens and comparing their ages to crater counts in the region. Lots of craters implies an older surface long-pummeled by impacting meteoroids. Fewer craters indicate younger terrain.

These maps show the moon's appearance Friday night, Nov. 27 from the Americas. When seeking Rümker, use medium magnification, around 75-100x. If the air is still and steady you can increase the power to 150x or more to see the feature's textures and shading more clearly. Virtual Moon Atlas / Christian Legrand and Patrick Chevalley

One of my favorite things is using my telescope to hunt down landing sites as a way to connect to an ongoing mission. It's fun to be there. Because the moon is so close, Mons Rümker is an easy catch in a 4-inch or larger telescope. The formation first comes into view on Nov. 27, the same time Chang'e 5 achieves lunar orbit. To my eye, Rümker looks like a broad, low-relief mound resembling a glop of warm pudding. It remains in view through Dec. 10 so you'll have lots of opportunities to look. 

This is what Mons Rümker looks like through a medium-sized telescope around 200x when it's near the lunar terminator (day-night boundary on the moon) as it will be on Nov. 27. Oliver Pettenpaul

Rümker's located way over on the west side of the moon in Oceanus Procellarum (Ocean of Storms). When the sun angle is low, as it will be on the 27th and 28th, you'll see the dappled, rounded forms of the largest domes best. Be aware that because it's near the edge of the moon Rümker will appear "squished" or foreshortened from our perspective. Only an orbiting astronaut or lunar satellite can see the mound from overhead.

I photographed Mons Rümker at 7 p.m. CST, Nov. 27 shortly after the sun rose there. It looks like a little bump, shaded on one side and sunlit on the other. Bob King

Although the landing zone includes Mons Rümker, the preferred touchdown site lies to the northeast of the complex in a relatively smooth region of similar rock. Since the mission will finish up in two weeks or less before the return home, the lander isn't equipped with a special heater to survive the bitter cold lunar night. It will perform all of its work during the 14-day-long lunar day when the sun is up and use its solar panels for power.

Let's hope the mission goes off without a hitch. As soon as images are available I'll post them here.