It’s the next best thing to being there. Eight days after safely landing on the lunar far side, China’s Chang’e 4 lander took this first panoramic postcard of its landing site in von Kármán Crater. Look around and you’ll see numerous crater pits, hills on the horizon and the Jade Rabbit 2 rover. Interesting thing about the moon’s horizon. Since the moon is only about a quarter the size of the Earth, the horizon is much closer, only about 1.5 miles (2.4 km) away. Here’s what Apollo 11 astronaut Buzz Aldrin had to say about it:
“On Earth, we have no awareness of the horizon’s curvature. The horizon was much closer than I was used to, and I even felt a bit disoriented.”
Remember the early, “orange” photos from the landing? The panorama photo has also been color corrected to show the moon’s truer, more neutral color. Compare it to the Apollo photos, and you’ll see how similar they are. 80 separate images were stitched together to create the 360-degree view. As you play your eye across the scene, notice how the illumination changes. The area around the rover is washed out and shadowless because the sun is coming from directly behind. But away from the rover, the sun is off to the side, and shadows cast in the angled lighting reveal textures and details.
Chang’e 4’descent to a soft landing
Chang’e 4 is located 20,000 feet (6,000 meters) below lunar “sea level,” so the horizon is probably even closer than 1.5 miles. There are quite a few craters close to the lander — one measures 65 feet wide (20 meters) and 13 feet deep (4 meters) — so the rover’s handlers on Earth will have to carefully maneuver it to avoid falling into a “pothole.” Some of those look worse than the ones in my city of Duluth.
The video was assembled from 4,700 frames taken by the lander’s camera as it descended to the surface back on Jan. 3. The lunar dust or regolith appears to be on the thick side indicating more space weathering (from micrometeorites and the solar wind) and thus an older surface than some areas of the moon. This wouldn’t be surprising given that the far side has almost no lunar seas, which formed after the original lunar crust solidified. Instead, it appears to be made of the same material as ancient cratered highlands we see as the “white parts” of the moon on the near side.
Lunar night has begun for the mission and so far so good. Unlike the previous Chang’e 3 lander/rover this one appears to be surviving the bitter cold so far — both lander and rover are healthy. The moon’s temperature averages about 250° F in the daytime and 250 below at night. Radioisotope thermonuclear generators (RTGs) are providing the heat and power to keep the electrical systems functioning during the approximately 2-week-long lunar night. NASA’s Curiosity Rover uses the same technology which converts the heat from the radioactive decay of plutonium-238 into electricity.
The Jade Rabbit-2 (Yutu-2) rover rolls down onto the moon’s surface CNSA/CLEP
Although the lander and rover are put in “sleep mode” during the night, sensors on the lander will be measuring temperatures changes throughout the night and will transmit that information back to Earth when the probe is wakened during the daytime.
Like Earth, you can locate anything on the moon by knowing its latitude and longitude. The 0° lunar longitude line runs from the lunar north pole through the center to the south pole. Chang’e 4 is located at 177° east longitude or almost directly opposite the center of the near side. It’s latitude is 45° south, so you can use your imagination to visualize the location as directly behind and half-way between the backside’s center and bottom edge. As far as picturing the sunlight-darkness cycle, you can do that by keeping track of the moon phases as seen from Earth. From about first quarter moon (evening half-moon) to last quarter (morning half-moon), the rover and lander experience night. Then, from last quarter to first quarter, they’re in sunshine. Put that in your mind’s eye next time you gaze at the moon.