The Indian Space Research Organization (ISRO) said on Saturday that India's Chandrayaan 2 lunar spacecraft had made the first-ever observation of the effects of the Sun's Coronal Mass Ejection (CME) on the Moon, marking a significant scientific accomplishment.
One of the scientific tools on board the orbiter, Chandra's Atmospheric Composition Explorer-2 (CHACE 2), was used to make the discovery. When a CME struck the lunar surface, the observations revealed a considerable increase in the overall pressure of the Moon's dayside exosphere, or its incredibly thin atmosphere.
ISRO reports that during this event, the "number density," or total number of neutral atoms and molecules, surged by more than an order of magnitude. Long-standing theoretical models that had anticipated this impact but had never been seen firsthand were validated by this.
In a statement, the space agency added, "This increase is consistent with earlier theoretical models, which predicted such an effect, but CHACE 2 onboard Chandrayaan 2 has observed it for the first time."
High energy particles, primarily hydrogen and helium ions, are ejected into space by a huge explosion of plasma and magnetic field from the Sun's corona, or outer atmosphere.
The atmospheres and surfaces of planetary bodies may be impacted when such emissions reach them. Earth's magnetic field provides some defense against these impacts. But because the Moon lacks an atmosphere and a worldwide magnetic field, it is extremely vulnerable to the activities of the Sun.
When a sequence of CMEs were launched from the Sun toward the Moon on May 10 of last year, the unusual observation took place. Atoms on the lunar surface were knocked off and discharged into the exosphere by this strong solar activity, momentarily raising the density and pressure of the exosphere.
According to ISRO, this firsthand observation provides important information on how solar activity affects the Moon's ecology, information that may be essential as people prepare to construct future lunar dwellings and research facilities.
Extreme solar outbursts like this have the ability to momentarily change the lunar environment, which could make it difficult to build long-term bases there, ISRO noted.
The GSLV MkIII M1 rocket carrying India's second lunar exploration mission, Chandrayaan 2, was launched from Sriharikota on July 22, 2019. Eight scientific payloads were carried during the mission to investigate the Moon's surface, atmosphere, and mineral makeup.
The Orbiter is still fully operational and is still orbiting the Moon at a height of around 100 kilometers, whereas the Vikram lander lost communication during its September 7, 2019, landing attempt. For more than five years, it has been making important scientific observations.
The orbiter's array of equipment includes the CHACE-2 payload, which is specifically built to investigate the make-up and fluctuations of the lunar exosphere.
This unique observation has wider ramifications for next lunar missions in addition to improving scientific knowledge of space weather and its consequences on the Moon.
