The Indian Space Research Organization (ISRO) has set its sights on unlocking the enigmatic futures of Earth, Venus, and Mars through a series of cutting-edge planetary science missions. Partnering with esteemed academic institutions across India, ISRO is currently in the advanced planning stages for several missions that promise to unravel the mysteries of the rocky celestial bodies within our inner solar system. Over the course of the next decade, ISRO is poised to launch sample return missions to a primordial asteroid and our closest celestial neighbor, the Moon.

The inner solar system boasts three rocky worlds-- Venus, Earth, and Mars--each possessing unique characteristics that set them apart. While Mars grapples with a tenuous atmosphere perpetually eroded by the relentless forces of the Sun, its rovers persistently stumble upon traces of ancient water, hinting at a bygone era when the Red Planet was shrouded in a dense atmosphere. On the other hand, Earth thrives with its abundant liquid water, lush atmosphere, and the distinction of being the sole celestial body known to harbor life.

Venus, however, presents a starkly contrasting landscape. Wrapped in an even thicker atmosphere laden with elements inhospitable to terrestrial life, the planet's surface remains obscured by a dense veil of sulfuric acid clouds. The Venusian environment, characterized by searing heat and oppressive atmospheric pressure, has claimed the lives of many spacecraft attempting to reach its surface. Moreover, a significant portion of Venus's once-existing water has mysteriously vanished, leaving scientists perplexed about the reasons and timeline of this disappearance. Consequently, the fate that may await Earth in the distant future remains uncertain: whether it will evolve into a barren, arid world akin to Mars or succumb to a noxious, greenhouse-gas-ridden hothouse reminiscent of Venus.

ISRO, ever the visionary, is preparing a tandem of planetary science missions to demystify this uncertainty—a mission to Venus, christened Shukrayaan, and a subsequent mission to Mars. Shukrayaan, aptly named the Venus Orbiter Mission, seeks to probe the depths of Earth's enigmatic twin. Despite their apparent similarities, the secrets veiled beneath Venus's sulfuric acid shroud remain tantalizingly unexplored. From the blistering high-speed winds to the intricate topography of its surface and the enigmatic subsurface features, Shukrayaan is poised to reveal it all. Equipped with a versatile suite of instruments, including radar technology to penetrate the dense cloud cover, Shukrayaan is primed to examine Venus's clouds and outer atmosphere comprehensively. These groundbreaking instruments have been meticulously developed by esteemed research institutions across India.

Reflecting on the significance of this endeavor, ISRO Chairman S. Somanath remarked during an open lecture for the Indian National Science Academy (INSA), "For most of its existence, Earth was uninhabitable. Understanding the evolution of planetary bodies, such as Venus and Mars, is paramount. Only by studying these celestial neighbors can we unravel the factors that render Earth habitable." A profound comprehension of planetary atmospheres is a prerequisite for informed intervention, if necessary, to safeguard Earth from a fate akin to Mars or Venus.

Mangalyaan, ISRO's initial foray into Martian exploration, aimed to showcase the organization's capabilities in reaching the Red Planet. With its follow-up mission, Mangalyaan 2, ISRO broadens its scientific objectives. Currently in the conceptualization phase, ISRO scientists are diligently devising the spacecraft's configuration and payload selection. The mission will feature a hyperspectral camera, a panchromatic camera, and a radar system to delve into Mars's primitive crust. This amalgamation of instruments will empower the orbiter to monitor ongoing geological activities on the Martian surface, such as shifting sand dunes and cascading boulders.

Around the year 2025, ISRO is poised to embark on a collaborative lunar mission with the Japan Aerospace Exploration Agency (JAXA) named Lunar Polar Exploration (LUPEX). This venture, involving an ISRO lander launched aboard a JAXA rocket housing a JAXA rover, aims to investigate the presence of water on the Moon's surface. The findings from LUPEX hold the promise of guiding the future lunar endeavors of spacefaring nations worldwide. Beyond LUPEX, often referred to as Chandrayaan 3 within the Indian lunar exploration program, ISRO is in the nascent stages of formulating further lunar missions.

Looking ahead to the post-2025 era, ISRO has charted an ambitious roadmap for future planetary science missions. Chandrayaan 5, for instance, is set to excavate lunar regolith, analogous to the Luna 27 and Luna 28 missions by Russia's Roscosmos. Employing a rotary-percussive drill capable of digging up to a meter and a half below the lunar surface, Chandrayaan 5 aims to retrieve lunar material for in-depth analysis, contributing to our understanding of our celestial neighbor. The mission intends to land in a region marked by volcanic and tectonic activity on the near side of the Moon.

In the context of Mangalyaan 3, ISRO contemplates deploying a rover on the Martian surface. Scientists intend to target ancient hydrothermal deposits that once graced a long-vanished Martian seafloor. Earth's hydrothermal vents teem with resilient life forms, prompting the study of Martian hydrothermal deposits as a key determinant of ancient Martian habitability. ISRO is actively evaluating landing zones within the southern highlands—a region hitherto unexplored by previous Martian missions.

These forthcoming missions necessitate the development of indigenous technologies for robotic spacecraft by research institutions across India. These technologies encompass sample-collecting arms, drilling mechanisms, and modular capsules designed for sample transportation. Chandrayaan 6 envisions a sample return mission, accompanied by a precision landing at a pre-selected site. Additionally, ISRO is exploring the possibility of a sample return mission targeting a primitive comet or asteroid, with projected launch windows between 2030 and 2035.

As ISRO embarks on this remarkable journey into the future of planetary science, it reaffirms its commitment to unraveling the cosmic mysteries that surround us, shedding light on the fate of Earth, and ensuring the continued advancement of humanity's understanding of the universe.