Syllabus:

GS-3: Awareness in the fields of IT, Space, Computers, robotics, nano-technology, bio-technology and issues relating to intellectual property rights.  

Context: 

Astronomers have recently discovered an asteroid 2025 PN7, the earth's latest quasi-satellite. 

Asteroid 2025 PN7 

• It is a small asteroid revolving around the Sun while remaining near Earth.
• The team found that 2025 PN7 had been in a quasi-orbit for about 60 years already and would likely be nearby for another 60 or so years before departing.
• It was first spotted in August by the Pan-STARRS 1 telescope in Hawaii.
• It is a member of the Arjuna asteroid class. It is just 62 feet wide, observable only with high powerful telescopes.
• 2025 PN7 follows an orbit very similar to that of the earth, making it appear to ‘hover’ nearby even though it’s not gravitationally bound to the planet.
• According to a researcher, 2025 PN7 is also the earth’s seventh known quasi-satellite.

Quasi-Satellite: 

• A quasi-satellite is a small body in a 1:1 orbital resonance with a planet, maintaining proximity to it over many orbital periods while orbiting the Sun rather than the planet itself.

Arjuna Asteroid Class

• Arjuna asteroids are a dynamical class of near-Earth objects (NEOs).
• They have Earth-like orbits, meaning their semi-major axis, eccentricity, and inclination are very close to Earth’s.
• This feature allows them to stay near Earth for long periods and sometimes act as quasi-satellites or temporary companions.
• The broader interest stems from the Arjuna asteroid class, first hinted at with the discovery of asteroid 1991 VG more than three decades ago. 
• Today, astronomers are aware of more than 100 such Arjunas, which together form a secondary asteroid belt.

Notable Examples: 

• 2014 OL339 – A temporary quasi-satellite of Earth.
• 469219 Kamoʻoalewa (2016 HO3) – Often called “Earth’s constant companion.”
• 2025 PN7 – The newest reported Arjuna-class asteroid, identified as a quasi-moon.

Significance of the Findings

• Advancing Scientific Knowledge: Its presence adds to astronomers’ understanding of the shifting population of asteroids near Earth.
• Strengthening Planetary Defense: Asteroids like 2025 PN7, which stay near Earth for long durations, provide an ideal testbed to refine tracking and deflection strategies, including techniques such as kinetic impactors and gravity tractors.
• Resource Utilisation: Quasi-satellites like 2025 PN7 may contain valuable resources such as water ice and metals, making them potential targets for asteroid mining and in-situ resource utilization (ISRU) to support long-term human presence in space.
• Stepping Stone for Deep-Space Missions: It can serve as nearby proving grounds for life-support, resource use, and deep-space propulsion, offering practice for crewed Mars missions and asteroid redirection projects.

Pan-STARRS 1 telescope

• The Pan-STARRS 1 (PS1) telescope is a key component of the Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) project, designed for wide-field astronomical imaging, particularly for finding and tracking near-Earth objects (NEOs). 
• It is a 1.8-meter diameter telescope located near the summit of Haleakala on the Island of Maui. It is equipped with the world's largest digital camera, with almost 1.4 billion pixels.
• The telescope observes in multiple wavelength bands, including visible and near-infrared light. 
• The system's capabilities help in spotting supernovae and other sudden astronomical events. 
• Data from PS1 also contributes to the study of outer solar system objects like Kuiper Belt objects and centaurs. 

Sources:
The Hindu
Explainers
Hawaii.