On October 19, 2017, astronomers at the Haleakalā Observatory in Hawaii made a groundbreaking discovery—the first known interstellar object passing through our solar system. This mysterious visitor, later named ‘Oumuamua, which means “messenger from the past reaching out to us” in Hawaiian, sparked intense scientific debate. A pair of Harvard researchers speculated that it could be an artificial probe sent by an advanced extraterrestrial civilization, possibly a piece of alien technology exploring the cosmos.
Everything within our solar system follows predictable, closed-loop orbits—some nearly circular, others elongated. However, ‘Oumuamua trajectory was an open-ended orbit, indicating its origin outside our solar system. Even more puzzling, astronomers observed an unexpected acceleration as it left the inner solar system, fueling theories that it might be an artificial construct rather than a natural object. The idea that ‘Oumuamua could be an alien spacecraft intrigued scientists and the public alike, reigniting the age-old question: Are we alone?
While speculation ran wild, scientific responsibility demanded careful analysis. Most astronomers concluded that ‘Oumuamua was likely a comet, similar to 2I/Borisov, another interstellar object detected a year later. However, due to its high speed and fleeting visibility, definitive conclusions remained elusive. The object’s brightness provided limited information, allowing scientists only a brief window—about a week—to estimate its shape, size, rotation, and color, which was believed to be reddish. Many unanswered questions about ‘Oumuamua remain, emphasizing the need for rapid-response space missions.
Currently, space exploration missions take years to develop, requiring lengthy approval processes before launch. In the case of ‘Oumuamua, such delays made studying it up close impossible. Scientists are now advocating for pre-built, ready-to-launch missions that can quickly respond to new discoveries. The ability to rapidly deploy spacecraft could be humanity’s best chance to closely examine an interstellar visitor in the future. Given the vast distances between solar systems, interstellar travel remains beyond our current capabilities—unless warp drive technology, as envisioned in science fiction, becomes a reality.
Despite never having encountered an interstellar object up close, past missions have provided valuable insights. In 2014, the European Space Agency’s (ESA) Rosetta probe successfully rendezvoused with Comet 67P, making history as the first mission to land a probe on a comet’s surface. Between 2014 and 2016, Rosetta observed the comet extensively, leading to unexpected discoveries, such as the revelation that 67P’s water composition differed from that of Earth’s oceans. This finding challenged previous theories that comets could have been the primary source of Earth’s water.
Scientists continue to analyze data from the Rosetta mission, using it to unravel the mysteries of the solar system’s early days. Comets, often considered remnants from the solar system’s formation, hold crucial clues about Earth’s origins and, ultimately, the emergence of life. However, as comets orbit the Sun, they undergo changes, losing gases and altering their composition. To study a pristine comet—one that has never been exposed to the Sun’s heat—ESA proposed the Comet Interceptor mission.
Unlike past missions targeting known comets, Comet Interceptor aims to investigate a newly discovered comet from the distant Oort Cloud, an outer region of the solar system believed to contain trillions of comets. The mission involves deploying a primary spacecraft along with two smaller probes to capture detailed images and data. While its primary objective is to study Oort Cloud comets, Comet Interceptor could also be repurposed to examine an interstellar object like ‘Oumuamua or Borisov, making it the first mission capable of such an endeavor.
One of the biggest challenges in studying new comets or interstellar objects is the limited time between detection and their closest approach. Traditionally, space missions take years to develop, making rapid deployment nearly impossible. To overcome this, the Comet Interceptor spacecraft will be stationed at the Earth-Sun Lagrange Point, a stable region in space where gravitational forces allow it to remain in a fixed position. There, it will wait for up to five years, ready to launch toward a suitable target as soon as one is identified.
The success of the Comet Interceptor mission could provide unprecedented insights into the formation of our solar system and the nature of interstellar objects. Meanwhile, researchers at MIT are designing a separate mission specifically targeting interstellar visitors. Their proposal, the Dynamic Orbital Slingshot for Rendezvous with Interstellar Objects, suggests using solar sail technology to keep a probe stationary in space until a target appears. Once an interstellar object is detected, the probe would harness the Sun’s gravity to slingshot itself toward the target, achieving a close-up view.
This MIT-led initiative recently received phase-one funding from NASA, granting researchers nine months to refine their plan before applying for further funding. If successful, the project could lead to a revolutionary new approach for studying interstellar objects.
These ambitious missions coincide with advancements in observational technology. The upcoming Vera C. Rubin Observatory, expected to be operational within the next few years, will significantly enhance the ability to detect faint interstellar objects and pristine comets. Scientists predict that once the observatory is fully functional, discoveries of interstellar visitors may become an annual occurrence, opening the door to unprecedented scientific exploration.
By preparing for rapid-response missions, humanity may finally have the opportunity to study objects from beyond our solar system, offering new insights into the cosmos and our place within it.
