Tell about James Webb Space Telescope ?

This refers to the early stages of the universe after the Big Bang started the universe as we know it today. In the first stages after the Big Bang, the universe was a sea of particles (such as electrons, protons and neutrons), and light was not visible until the universe cooled enough for these particles to begin combining.

Looking at galaxies is a useful way to see how matter is organized on gigantic scales, which in turn gives us hints as to how the universe evolved. The spiral and elliptical galaxies we see today actually evolved from different shapes over billions of years, and one of JWST's goals is to look back at the earliest galaxies to better understand that evolution.

The powerful $8.8 billion spacecraft is also expected to take amazing photos of celestial objects like its predecessor, the Hubble Space Telescope

Luckily for astronomers, the Hubble Space Telescope remains in good health and it's probable that the two telescopes will work together for JWST's first years. JWST will also look at exoplanets that the Kepler Space Telescope found, or follow up on real-time observations from ground space telescopes.

JWST has a long development history. It went over budget and affected NASA's astronomical funds, which among other things, caused the agency to pull out of some joint missions with the European Space Agency.

Even while Hubble was being prepared for its space mission, a successor telescope was being planned that would improve on Hubble's capabilities. After early-stage studies in the 1990s, NASA embarked on a "faster, better, cheaper" era that was intended to use electronics miniaturization and tiger teams to reduce the cost of space missions.

This caused a reformulation of these early telescope studies into something called the Next Generation Space Telescope, which was then pursued well into the 2000s.

The first version of NGST called for an 8-meter aperture and for the telescope to be flown to L2. NGST was renamed the James Webb Space Telescope in 2002, after a former NASA administrator. The project was estimated to cost $4.5 billion in about 2005, but cost overruns occurred in the years following.

In 2010, an independent review panel for JWST warned that the telescope would be substantially over budget. The panel noted that following a NASA confirmation review in 2008, cost growth and schedule delays were "associated with budgeting and program management, not technical performance.

Among the problems the review cited were poor estimation procedures and a baseline budget that was too low. The panel suggested the earliest launch date possible would be 2015.

Around 2010, NASA and the European Space Agency were cooperating on several large-scale missions, including ExoMars and a predecessor mission to Athena, an X-ray telescope.

By 2011, however, ESA said it would rather go forward on these missions by itself. NASA had cut back on its other astrophysics programs to allow for JWST development, including pulling out of ExoMars.

Further, the U.S. National Science Foundation Decadal Survey of 2010 (which establishes astronomical programs of priority) had ranked the joint ESA missions lower than other initiatives, ESA said in a statement at the time.

The JWST is named for former NASA chief James Webb. Webb took charge of the space agency from 1961 to 1968, retiring just a few months before NASA put the first man on the moon.