The nc (or netcat) utility is used for just about anything under the sun involving TCP or UDP. It can open TCP connections, send UDP packets, listen on arbitrary TCP and UDP ports, do port scanning, and deal with both IPv4 and IPv6.
Can you connect to jupiter.challenges.picoctf.org at port 64287 to get the flag?
nc domain/IP portnc jupiter.challenges.picoctf.org 64287