Since the launch of Pioneer 10 in 1972, humans have been launching objects into outer space for 50 years. As of right moment, five spacecraft have either arrived to or are rapidly reaching the outer reaches of our solar system: Voyager 1, Voyager 2, New Horizons, Pioneer 10, and Pioneer 11.
The majority of these probes have confounded expectations and are continuing to function well after the completion of their initial mission objectives. These spacecraft were initially intended to explore our neighbouring planets, but they are now blazing a trail outside of the solar system, giving astronomers unique vantage points in space. In 2022, they have been very active.
Voyagers 1 and 2
The Voyager missions celebrated a very special anniversary this year: 45 years of operations. From close fly-bys of the outer planets to exploring humans’ furthest reach in space, these two spacecraft have contributed immensely to astronomers’ understanding of the solar system.
Voyager 1 has been in interstellar space for ten years, and it’s still going strong, according to Linda Spilker, a planetary scientist at NASA’s Jet Propulsion Laboratory (JPL) in California and the project scientist for the Voyager mission.
This year’s mission encountered a significant setback when the spacecraft started transmitting its location data incoherently. The cause was identified and operations were resumed once the engineers realised that the spaceship shouldn’t have been using a problematic piece of computer gear.
However, such occurrences are to be anticipated with an old spacecraft. The team is also actively controlling each spacecraft’s power supply, which is depleting annually due to the radioactive generators’ deteriorating efficiency. To everyone’s surprise, the scientific instruments are still functioning flawlessly despite the fact that mission workers turned off heaters keeping them warm throughout this year’s mission.
The edges of the solar system have been full of surprises, too. It would make sense that plasma from the sun becomes more sparse and spread out as you move away from the center of the solar system, but in fact, the Voyagers have encountered much denser plasma after crossing the heliopause. Astronomers are still puzzled about that one.
Pioneer 10 and 11
Due to their status as, you guessed it, pioneers, the Pioneer spacecraft have a particular place in the annals of space history. Unfortunately, these historic 50-year-old spacecraft are no longer operational; Pioneer 10 stopped receiving signals in 2003, while Pioneer 11 hasn’t made touch since 1995.
But despite the fact that we are no longer directing them or launching their rockets, both of these spacecraft remain visible signs of human existence in the solar system and are still travelling. The principles of physics state that once a spacecraft is launched on a route out of the solar system, it cannot be stopped unless some external force alters the trajectory.
With its launch in 2006, New Horizons is by far the most recent of these revolutionary missions. This probe has been zipping out of the solar system at a record pace since finishing its well-known flyby of Pluto in 2015. It is expected to arrive at the heliopause around 2040.
As its first mission extension, it successfully executed a flyby of the smaller Kuiper Belt object Arrokoth in 2019 in addition to completing its initial goal. The spacecraft went into hibernation earlier this year since an extended mission wasn’t yet authorised. The second Kuiper Belt Extended Mission, or KEM2, is officially underway, and the team is eager to get started. KEM2 started on October 1 but will remain in hibernation until March.
The mission team is currently getting ready for fascinating new observations. The team is ready to use New Horizons as a powerful observatory in the far reaches of the solar system, providing a perspective we can’t achieve here on Earth. This is thanks to cutting-edge instruments, which are far more sophisticated than those the Voyagers carried in the 1970s.
In particular, Bonnie Burrati, a planetary scientist at JPL, is anticipating fresh perspectives of Kuiper Belt objects (KBOs), the ice and rock fragments beyond Neptune. According to her, the distinctive location of New Horizons in the outer solar system offers fresh perspectives on these KBOs. Based on how light scatters and casts shadows on the objects, various viewpoints can inform astronomers about the objects’ surfaces’ roughness, among other things.
Even beyond the initial purview of planetary research covered by New Horizons, this subsequent extended mission will explore. Now, in addition to the Voyagers, the spacecraft will deliver measurements of the cosmic rays and background light in space that are better than ever, track the distributions of dust throughout our solar system, and gather essential data on the sun’s influence. Astronomers can map out abnormalities in the solar system’s structure thanks to the three operational far-out spacecraft’s independent courses of travel.
Fortunately for New Horizons, evidence point to the spacecraft having enough power to continue through the 2040s and probably beyond, travelling 300 million miles (480 million kilometres) further into unexplored territory each year.