China takes off towards Earth after collecting samples from the far side of the Moon

In a new demonstration of its indisputable state of space fitness, China has managed to take off a probe from the far side of the Moon, bringing with it samples from that area for the first time in history. The probe Chang’e 6, which landed on Sunday in that least studied region of the satellite, in a mission calculated to the millimeter to be back on Earth in just 53 days from its launch. The China National Space Administration, which had not offered images of the probe, showed in the early hours of Tuesday photos and videos taken after landing, during the collection of materials and even from the moment of lunar takeoff. China reported that the ascending module of the probe has already reached the predetermined orbit around the Moon.

China assured that the probe has overcome “the challenge of high temperatures on the far side of the Moon”, more specifically those of the Aitken-South Pole Basin, where it landed without problem on June 2, after taking off from Earth. on May 3. According to the Chinese space agency, all systems “functioned correctly and carried out scientific explorations as planned.” In the last decade, Beijing has achieved success in its space program, with the consolidation of its own space station and the landing of four probes on the Moon. Two of them, the Chang’e 5 and now the Chang’e 6In addition, they have managed to recover samples from the lunar surface for research, something that no other country has achieved in the new space race.

How important are samples?

Apart from being the first to be obtained from the hidden side, the fact that they are obtained at great depth and in the polar regions increases the possibility that they contain water. Not many. Perhaps it does not reach 0.1% by weight, that is, the complete sample would only provide a few grams.

But, if so, it would represent a direct confirmation of the presence of that substance in the subsoil of our satellite. So far, all evidence is based on remote detections of the presence of hydrogen and hydroxyl ions. Really touching the selenite water would be an event of the first magnitude.

How did you obtain the samples?

The Chang’e 6 It has a drill that allows you to drill into the ground and collect samples up to 2 meters deep. It is not the first to go so far: the USSR already achieved something similar with its Moon 26 in 1976.

Since there is no air on the Moon, it is impossible to aspirate the sample as it is drilled. The drilling tool is wrapped in a flexible tube (the Soviets used plastic, the Chinese used cloth, perhaps silk) so that the pulverized rock fills it, dragged by the spiral of the drill bit itself.

Once filled, the tube is rolled inside an airtight metal cylinder. That cylinder, capable of holding a couple of kilos of sample, will be the one that returns to Earth.

Has it taken off directly from the Moon?

That’s what the Russians did many years ago: take off vertically and head directly towards the Earth, like a cannon shot without a guidance system. Although simple, this method suffered from many drawbacks, especially that it limited the landing area to a few places near the edge of the visible hemisphere.

The Chinese use a much more elaborate system, reminiscent of the manned Apollo spacecraft. The Chang’e It consists of a descent module, with the braking engine and landing gear, and an ascent capsule. The same scheme as the American lunar module.

The ascent capsule takes off powered by its own engine and will rendezvous with the orbital section of the ship. Inside it has the cylinder with the samples.

The two ships meet and dock automatically. This is perhaps the most spectacular phase of the mission and the one that presents the greatest technical difficulties. At the moment of contact, metal nails secure the connection and mechanical impellers transfer the sample container to the interior of the return capsule, located inside the orbital module.

Once this operation is completed, both ships separate and the orbital module continues to revolve around the Moon until it reaches a point in its orbit suitable to undertake the return journey.

Where did he land? Chang’e 6?

In the Aitken depression, a huge circular near the south pole, which also extends along the far side. With a depth between 5,000 and 8,000 meters with respect to the average surface level, it is not only the largest impact scar on the Moon, but is among the largest in the solar system. On Earth, the coordinates of the landing site correspond to a point in the South Pacific, almost 3,000 kilometers east of New Zealand.

How did it communicate with Earth?

Thanks to a communications satellite (Quequiao 2) that China had launched last March. It revolves around the Moon in a 24-hour orbit, covering part of the far side and the southern polar region. It’s not the only one; Its equivalent Quequiao 1 is anchored at the Langrage L2 point of the Earth-Moon system, providing coverage to another lunar probe, the Chang’e 4 and his small rover that was the first to land in the invisible hemisphere and which still works.

What was the landing process like?

China has developed a truly spectacular automatic landing system. It has not had any failure in the four attempts made. The system combines radar to measure the distance to the ground at the beginning of the maneuver and Lidar (a system similar to radar, but that sends pulses of laser light instead of electromagnetic waves) for the terminal phase. A system of television cameras photograph the terrain during the descent to identify dangerous rocks or fissures and an obstacle avoidance system moves the ship to one side or the other until it is positioned over a safe point.

The braking motor shuts off a few meters above the ground, so the ride ends in free fall. The low lunar gravity and shock-absorbing landing gear mean that the impact is inconsequential.

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