As of 2021, what is the most powerful telescope ever built?

NASA’s (National Aerospace and Space Adminstration) James Webb Space Telescope is a partnership with the European and Canadian space agencies and set to launch on December 2021. James Webb Telescope is the next great space science observatory following Hubble, designed to answer outstanding questions about the Universe and to make breakthrough discoveries in all fields of astronomy.

James Webb Space Telescope will see farther into our origins: from the formation of stars and planets, to the birth of the first galaxies in the early Universe. It is also the world's biggest, most powerful and expensive space telescope ever built, $8.8 billion was spent on space craft development from 2003 and 2020. $851 million is also planned to support its 5 years of operation. Adjusted for inflation in 2020, the lifetime cost to NASA (National Aerospace and Space Adminstration) will be approximately $10.8 billion.

James Webb Space Telescope is named for James E. Webb who was a NASA administrator from 1961 to 1968 who played an integral role in the Apollo program.