Chapter 1: The Mission Overview

The Interstellar Probe is set to venture further into space than any other spacecraft before it—much further than we have ever imagined, and it could launch in the near future.

This ambitious mission has the potential to transform our perception of the Solar System. Currently, only a few robotic explorers, including Pioneer 10 and 11 from the early '70s and the Voyager missions launched in 1977, are patrolling the outskirts. Meanwhile, New Horizons, which made history by visiting Pluto, is racing further into the vast expanse between stars.

At these incredible distances, it's practical to express measurements in astronomical units (AUs), which is the average distance from the Earth to the Sun. For instance, Neptune is located about 30 AUs from the Sun, while Pluto sits at approximately 40 AUs.

Stay tuned for a special episode of Astronomy News with The Cosmic Companion on May 25, featuring Dr. Elena Provornikova from the Johns Hopkins Applied Physics Laboratory (APL), who leads the heliophysics research for the Interstellar Probe.

The boundary of our Solar System is often defined by where the solar wind, a stream of particles emitted by the Sun, gives way to interstellar space. This boundary, known as the heliosphere, is located around 120 AUs from the Sun.

In 2008, Voyager 1 crossed into the heliosphere, followed by Voyager 2 in 2012. Although these robotic explorers detected this transition, many questions remain about how our Sun interacts with the surrounding interstellar medium. The instruments aboard these crafts, designed in the 1970s, are showing signs of aging after over 40 years in space, leaving us with significant gaps in our understanding of the interstellar expanse.

The upcoming Interstellar Probe is expected to join this elite group of space explorers, with a launch anticipated in the early 2030s, reaching the heliosphere approximately 15 years later. In contrast, the Voyager missions took 35 years to achieve this landmark.

“Humanity has always defined itself by overcoming challenges. We cherish the moments when we strive to aim higher, break barriers, reach for the stars, and unveil the mysteries of the universe,” says Cooper from the film Interstellar.

The Interstellar Probe aims to travel an astounding 1,000 AUs from the Sun, far surpassing the distances covered by previous missions.

Upon reaching these remote areas, the spacecraft will investigate the heliosphere, potentially unlocking secrets about its origins. Dr. Elena Provornikova states, “The Interstellar Probe will venture into the uncharted local interstellar space, a realm humanity has never explored. For the first time, we'll capture an image of our vast heliosphere from the outside, revealing the true nature of our solar system.”

Chapter 2: Scientific Objectives and Instrumentation

Over 500 contributors are collaborating over four years to brainstorm the types of instruments that the Interstellar Probe should carry, making it the first mission to venture deep into interstellar space. Ideally, the spacecraft will be equipped with a variety of scientific tools to study the heliosphere, including optical cameras, instruments for analyzing dust, and infrared cameras to map this dusty environment.

At the European Geosciences Union General Assembly on April 26, Elena Provornikova and fellow APL researcher Pontus C. Brandt discussed the potential science to be conducted on the Interstellar Probe.

Researchers aim to study how plasma interacts with gases between stars, providing insights into this interstellar boundary. By examining energetic, neutrally-charged atoms, they may succeed in capturing the first image of the heliosphere, which serves as a shield against high-energy cosmic rays.

The Interstellar Probe may also enable observations of extragalactic background light from the early phases of our galaxy's formation—something that cannot be observed from Earth. As the Sun orbits the galaxy approximately every 250 million years, it traverses the Local Interstellar Medium (LISM), which contains varying concentrations of primarily hydrogen gas. Currently, our Sun is moving through the Local Interstellar Cloud, often referred to as the Local Fluff. There are indications that we might be nearing the edge of this tenuous region.

“The properties of the LISM are crucial to understanding the Sun's galactic surroundings and how they influence our heliosphere. The Interstellar Probe will be NASA's first mission dedicated to uncovering the true nature of the LISM and determining whether the Sun is about to enter a new region within it,” according to an abstract from the EGU presentations.

This mission is poised to answer critical questions about our position in the galaxy and provide insights into how the heliosphere adapts as it encounters interstellar clouds. Such knowledge could enhance our understanding of how Earth might be impacted by galactic cosmic rays.

“This mission would mark humanity's inaugural step into the galaxy and could become one of NASA's boldest ventures in space exploration. Discussions about this mission have been ongoing since 1960, with propulsion often being a significant hurdle. Fortunately, advancements in propulsion technology and the development of larger launch vehicles have paved the way for this undertaking,” researchers have noted.

Thanks to modern boosters and a gravitational assist from Jupiter, the spacecraft is expected to achieve speeds exceeding 7.5 AUs per year—more than double the speed of Voyager 1 as it exits our Solar System.

“Building on previous missions, the team is using the New Horizons spacecraft as a foundational design, with necessary enhancements. Like the Pioneers, Voyagers, and New Horizons, the primary power source will be a radioisotope thermoelectric generator, providing dependable energy over long mission durations and vast distances from the Sun,” the team explains on the Interstellar Probe homepage.

The Interstellar Probe is engineered to last for 50 years. If it performs as expected, this groundbreaking spacecraft could signify a pivotal moment in our understanding of the solar system we inhabit.

James Maynard, the founder and publisher of The Cosmic Companion, is a New England native now residing in Tucson with his wife, Nicole, and their cat, Max.

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