Core Insights - The Voyager spacecraft, launched in 1977, are the only two spacecraft with operational scientific instruments that have successfully exited the solar bubble into interstellar space, providing unique insights into the heliosphere and beyond [1][2][5] Group 1: Voyager Mission Overview - Voyager 1 and Voyager 2 have explored the outer planets, including Jupiter, Saturn, Uranus, and Neptune, revealing significant discoveries such as volcanic activity on Io and the atmospheric composition of Titan [3][4] - The mission was designed to take advantage of a rare planetary alignment, allowing for a cost-effective flyby of multiple outer planets [2][3] Group 2: Scientific Discoveries - Voyager spacecraft have provided data on the heliosphere's boundaries, including the termination shock and heliopause, which are critical for understanding solar wind interactions with interstellar medium [4][5] - The spacecraft have revealed complexities in the heliosphere, including variations in solar activity and its effects on the surrounding space environment [2][5] Group 3: Future Exploration - NASA's IBEX mission has been launched to study high-energy neutral atoms from the heliosphere's edge, contributing to the understanding of the interstellar boundary [6][7] - The upcoming IMAP mission aims to provide a clearer picture of the heliosphere and its interactions with the interstellar medium, enhancing the data collected by Voyager [7][8] Group 4: Challenges and Limitations - The aging Voyager spacecraft face power limitations, with their radioisotope thermoelectric generators operating at about half their original power, raising concerns about the longevity of their missions [11] - Despite the wealth of data collected, scientists still face challenges in fully understanding the heliosphere's structure and dynamics due to the limitations of current observational capabilities [10][11]