1: They are both necessary for the construction of The James Webb Space Telescope ( JWST ) , intended as the successor to the Hubble instrument that has been operating in space for 25 years . 2: But there are limits to how far it can see . 3: Hubble has helped make major discoveries but there are limits to how far it can see into space .
1: the Hubble instrument 2: limits 3: Hubble