India reaches the moon: Chandrayaan-3 sends breathtaking pictures

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Humanity is in the midst of a new and improved era of lunar exploration. Dozens of probes are currently being built to contribute to our knowledge of the Moon from various parts of the world. India is part of this adventure with its third mission to our natural satellite, Chandrayaan-3. It successfully entered lunar orbit and is preparing for a landing attempt at the south pole of our satellite, leaving incredible images along the way.

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Photograph of the Chandrayaan-3 probe during one of its pre-launch tests. Credits: ISRO.

The way to the Moon

Chandrayaan-3 took off last July 14, from India, aboard a GSLV MK3 rocket. Due to limitations in the payload capacity of the launcher, the probe cannot perform a direct flight. Instead, it requires a slower approach of repeated orbits around the Earth.The Moon was then launched, executing engine ignitions to raise the apogee and after 25 days of traverse finally intercepting the Moon. This strange mission profile takes advantage of the Oberth effect, where a probe optimizes engine ignitions when traveling at higher speed at its perigee.

On August 5 at 19:15 Indian Standard Time, Chandrayaan-3 succeeded in entering the Moon's orbit. This is the third time that ISRO, the Indian space agency, has achieved such a feat.. The back thrust maneuver, i.e., firing the engines to reduce its velocity, lasted 1835 seconds and left the probe in an orbit of 164 x 18 074 kilometers above the surface. Subsequently, on August 9 at 14:00 Indian Standard Time, it performed the first of 5 maneuvers to reduce apogee to 4 313 kilometers.

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Infographic with information on Chandrayaan-3's current trajectory and maneuver. Credits: ISRO.

The probe consists of a propulsion module, a lander and a rover. The last two will reach the South Pole on August 23. Making India the fourth nation to land on the surface.

Images from lunar orbit

ISRO constantly announces updates on mission progress and probe status, but it wasn't until days after entering lunar orbit that we got our first glimpse of the Moon from Chandrayaan-3.. During the insertion maneuver, or LOI, the probe captured incredible images of the southern hemisphere of the Moon before plunging into the night region.

Using maps of the Moon created by previous probes and telescopes, it is possible to compare the craters captured in the images and determine the position of Chandrayaan-3. More precisely, the Hausen and Bailly craters are clearly visible and easy to identify.

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Comparison between the LROC map of the Moon and the Chandrayaan-3 images. The craters Hausen (left) and Bailly (right) are highlighted.

In addition, it allows to compare the region shown with the future landing site. Although it is not visible in the images, it is possible to have a first idea of the distance at which it is located.

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Stereographic projection of the lunar south pole, showing the craters Hausen and Bailly (red) and the future lunar landing site (circled with purple cross).

Landing on the Moon is an incredibly complex task, but a first step towards reaching the rest of the solar system. The success rate is considerably low. So far it has performed without major problems and promises to fulfill its objective of landing gently and deploying the rover. Its useful life will be a maximum of fourteen days, until the Sun sets and the freezing temperatures put an end to the mission.

Francisco Andrés Forero Daza