The newest telescope will replace the Hubble as it ends its 31-year tenure monitoring deep space. Scientists and engineers have spent most of this time developing the James Webb to the tune of $8 billion (approximately ￡5.9 billion) and their work culminates with its launch today. Over the next few hours, several intricate processes will determine whether their efforts will result in a decade of enhanced cosmic insight or a smouldering wreckage somewhere in the Atlantic Ocean.

       Many rocket launches take place on the knife's edge, as while engineering has made them safer over time, there is always a possibility of failure.

       Today, operators will nail each aspect of the launch, as it presents several opportunities for failure.

       US space agency administrator Bill Nelson told the BBC that, as they look for a "big reward", they will also have to take a "big risk".

       READ MORE: 'Science superpower' UK plays key role in NASA's ￡7.5billion mission

       Both the rocket and its payload could end up in pieces or non-functional.

       The first task technicians working in South America must meet today is launching the rocket.

       They are using an Ariane 5, a two-stage European launch vehicle first developed for launch in 1996.

       When the countdown at the Kourou spaceport ends, a controlled explosion will propel the 777-tonne rocket upwards.

       The Ariane 5 has a good track record, with a chain of 83 successful launches between 2003 and 2017.

       But of their 111 launches, engineers have recorded a total of five operating failures.

       These are split between three official failures and two "partial".

       In 2002, the launch of the first Ariane 5 ECA variant failed when a booster fault made it veer off course.

       Compared to the Hubble, it is two times larger and half as heavy.

       When the Hubble launched in 1990, it unfolded 2.4 metres of mirrors, and the James Webb must do the same with 6.5 metres.

       Space station staff will have to guide the telescope through the process, with failure possible at approximately 300 points.

       If any one of these fails to manifest, the whole telescope will struggle to function.

       Should this transpire smoothly, however, humanity will gain a tool for unrivalled scientific understanding.

       The James Webb is approximately 100 times more powerful than its predecessor, allowing scientists to look into the distant cosmos.

       There, they hope to find "pioneer stars", objects that formed billions of years ago and fed the universe the chemical compounds necessary to sustain life.

       The new telescope should see these as they existed back then, peering into a past never before accessible.