James Webb Space Telescope has enough fuel for more than ten years of science

NASA’s newest flagship space observatory should have enough fuel to more than double its minimum mission life peering into the history of the universe. The long-awaited James Webb Space Telescope, a collaboration with the Canadian and European space agencies led by NASA, launched into space on 25 December 2021 aboard an Ariane 5 rocket.

Often billed as the successor to the agency’s iconic Hubble Space Telescope, Webb – also known as the JWST – is designed to focus on infrared light, giving astronomers a look at the earliest days of the universe. Despite an ambitious science agenda, the mission was designed with just a five-year minimum lifetime. But with the observatory finally in space, NASA is confident that it will have enough fuel to see much more use than that.

“The Webb team has analysed its initial trajectory and determined the observatory should have enough propellant to allow support of science operations in orbit for significantly more than a ten-year science lifetime,” said NASA officials. “For comparison, the Hubble Space Telescope has lasted more than 30 years.

The agency noted that it can’t provide a specific estimate for how long the observatory will last. “The analysis shows that less propellant than originally planned for is needed to correct Webb’s trajectory towards its final orbit,” said NASA officials. “Consequently, Webb will have much more than the baseline estimate of propellant – though many factors could ultimately affect Webb’s duration of operation.”

Webb has completed two of the three burns required to see it to its destination; the final burn will take place nearly a month after launch and will mark the last step in the observatory’s perilous deployment process. Webb is destined to orbit a location known as the second EarthSun Lagrange point, or L2, which is nearly 1.5 million kilometres (1 million miles) from Earth in the direction opposite the Sun. Here Webb will be less vulnerable to solar radiation that can interfere with its infrared observations.

Lagrange points are sometimes nicknamed ‘parking spots’ for spacecraft, as they mark locations where the gravitational tugs of different bodies balance out. However, throughout its stay at L2, Webb will need to conduct occasional small thruster burns for station keeping and momentum management to retain its proper location and orientation in space. That’s what the propellant remaining after the third burn will be used for. And Webb will have more fuel left in its tank than NASA had dared to hope. The initial launch precisely targeted the observatory’s desired trajectory, meaning the spacecraft needed to spend less time and fuel on its first two correction manoeuvres.