In the past 50 years, humans have launched several vehicles into deep space, starting with the Pioneer 10 spacecraft in 1972. Currently, a total of 5 spacecraft have reached or are approaching the outer reaches of the Solar System, including Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, and New Horizons. Most of these space probes have exceeded their expected operational lifetimes and have provided astronomers with unique observations of space, sending back valuable data in 2022.
Voyager 1 and 2 spacecraft:
The Voyager mission marks a significant milestone this year, as it celebrates 45 years of operation. From close flybys of planets within the Solar System to exploring the farthest boundaries of space, these two spacecraft have greatly contributed to our understanding of the Solar System. Their current primary mission is to explore the termination shock, where the influence of the Sun ends. Voyager 1 crossed the heliopause in 2012, and Voyager 2 followed suit in 2018.
The outer reaches of the Solar System hold surprises. Researchers expected the plasma from the Sun to become thinner and spread out as it moved farther from the central region of the Solar System, but in reality, both Voyager spacecraft encountered denser plasma after crossing the heliopause. This has puzzled astronomers.
Pioneer 10 and 11 spacecraft:
The Pioneer spacecraft hold a special place in history as they were pioneering missions. The two 50-year-old spacecraft have ceased communication, with Pioneer 10 losing contact in 2003 and Pioneer 11 going silent after its final communication in 1995. However, both spacecraft have marked the presence of humanity in the Solar System and continue their drifting journeys even without guidance or the ability to fire their engines. According to the laws of physics, they will continue to travel until they are affected by some other celestial object altering their trajectory.
New Horizons spacecraft:
New Horizons is the youngest spacecraft compared to the others, launched in 2006. After completing its mission to fly by Pluto in 2015, this space probe is now traveling at record-breaking speeds away from the Solar System and is expected to cross the heliopause around 2040. In addition to accomplishing its primary mission, the spacecraft successfully performed a flyby of the Kuiper Belt object Arrokoth in 2019 as part of its first extended mission. Earlier this year, the spacecraft entered a hibernation mode until March 1, 2023, before commencing its next extended mission with new observations.
Bonnie Burrati, a planetary scientist at NASA’s Jet Propulsion Laboratory and a member of the New Horizons team, hopes to observe objects in the Kuiper Belt, such as icy blocks and rocks beyond the dwarf planet Pluto. The unique position of New Horizons at the edge of the Solar System will provide unprecedented viewing angles, revealing the surface roughness of these objects based on reflected light. The spacecraft will also provide measurements of background light and cosmic rays, monitor dust distribution in the system, and gather information about the Sun’s influence, supporting the Voyager spacecraft. Indications suggest that the spacecraft has enough power to survive beyond the 2040s. Each year, New Horizons can travel an additional 480 million kilometers, according to Space magazine.