What is "VSOP"?

Last modified: June 2022

Q. What is VSOP?
A. VSOP stands for "VLBI Space Observatory Programme", not for "Very Superior Old Pale" here, though most of all VSOP related persons love spirits (Sake), and a space VLBI project which carried out the astronomical observation with the satellite HALCA and the ground raido telescopes in all over the world.
Q. What is VLBI?
A. VLBI stands for "Very Long Baseline Interferometry", which makes observation using telescopes apart from each other. It produces high accuracy measurement for astronomy, navigation. We can achieve the same accuracy of 1,000 km diameter telescope when we observe with the baseline length (distance) of 1,000 km.

We use magnetic media (tapes, disks), or internet, and high accuracy atomic clock to combine multiple telescopes. We can get quite high resolution images for astronomical observation.

We can get the telescope with the size of the Earth diameter, but we need space VLBI to make the telescope larger than the size of the Earth.
Q. What is Interferometry?
A. Technology to use multiple antennas/telescopes as a single telescope. We can use common reference signals and correlation facility when the antennas/telescopes are located close enough. Recording media, offline correlation and high accuracy atomic clocks are used for the VLBI system to configure the interferometry for distant antennas/telescopes.  

Both VLBI and VSOP are one of interferometry systems.