What Happens on the Moon’s Surface When Something Jumps? Chandrayaan-3 Reveals the Truth

Written by Dr. Ananyo Bhattacharya, Research Fellow at University of Michigan, Ann Arbor , USA

Have you ever wondered what would happen if someone jumped on the Moon’s surface? Would a cloud of dust rise? And since the Moon has almost no atmosphere, how long would that dust take to settle? 

These are important questions to consider when planning lunar surface activities. Lunar dust, or regolith, can become electrically charged and, under certain conditions, may even get accelerated, potentially damaging spacecraft electronics or puncturing an astronaut’s spacesuit.

To explore such questions, beyond the engineering objectives, the Vikram Lander of Chandrayaan-3 performed a hop test. During this experiment, it briefly lifted off and landed again, capturing images of every moment. Watch the video below and observe closely. What do you notice?

India’s lunar mission Chandrayaan 3 achieved the first soft landing near the Moon’s South Pole in August 2023. The Vikram lander carried multiple payloads to the lunar surface to investigate the lunar plasma, surface composition, and subsurface thermal environment. It operated for one lunar day between 23rd August 2023 and 3rd September 2023. During its operation, the lander conducted a wide range of experiments and collected a lot of images to characterize the landing site.

On 2nd September, the Vikram lander conducted a hop test by hovering over the lunar surface and positioning itself about 40 cm away from its original location. It was a technology demonstration to show the lander’s ability to relocate and relaunch itself. It stands in line with the requirements of future missions for lunar sample return.

During the Apollo missions, the lander rocket was found to eject some surface dust near the surface. It almost looked like an instant spray of particles spreading radially away from the engine. In the absence of a thick atmosphere, these particles do not suspend in a gaseous medium and quickly fall to the surface. Looking at the swift action of the dust falling back goes against one’s general experience of “dust activity.” That’s the fun part about exploring these different environments, and especially bodies with tenuous atmospheres. The Apollo landings also caused a significant amount of dust activity, almost sandblasting any instruments around it. Apollo 12 is one prominent example, where the landing caused particulate impacts on the Lunar Module of the Surveyor 3 spacecraft [1].

What we saw during the Hop Test

Vikram lander conducted a hop over the moon on 2nd September, around 21:21 UTC. The video of the hop test shows particulate matter ejecting from the surface under the action of the Vikram lander thruster. In certain frames, pieces of rock fly away. The medium becomes opaque, blocking any light directly coming from the surface. Like the Apollo landing, the dust clears away seconds after the hop is complete. The characterization of dust activity is very important in the context of both robotic and human exploration of planetary environments.

The soft landing of Chandrayaan 3 generated a significant volume that was detected by the Chandrayaan 2 Orbiter High Resolution Camera (OHRC) and later analyzed by the Chandrayaan 3 Rover NavCam. These results were presented at the 55th Lunar and Planetary Science Conference. 

Significance of the hop test

The Hop Test over the lunar surface is a technology demonstration for the Vikram lander to test its capabilities to maneuver itself. It helps the scientists and engineers to prepare for future lunar missions and eventually the lunar sample return. A nominal amount of dust is lifted during the hop, and data from the Chandrayaan-3 instruments inform us about spacecraft charging and rocket-generated dust storms. 

How will it serve the future mission?

In terms of lunar exploration, India has plans for Chandrayaan-4, a mission designed to collect lunar samples and bring them back to Earth. A key component of the sample return was tested during Chandrayaan-3 by returning the Propulsion Module from lunar orbit to Earth’s orbit. These technology demonstrations pave the way to design advanced concepts for robotic exploration of the solar system. ISRO is also collaborating with JAXA for the Lunar Polar Exploration mission (LUPEX). In the long run, India aims to study the inventory of water and other volatiles on the Moon and develop capabilities for sustained exploration of the Moon.

Reference:

[1] Immer, C., Metzger, P., Hintze, P.E., Nick, A., and Horan, R., 2011. Apollo 12 lunar module exhaust plume impingement on lunar Surveyor III. Icarus, 211(2), pp.1089-1102.