The Ariane 5 rocket, with the James Webb Space Telescope, at its launch site in French Guiana.
This weekend there was two surprisingly good news about the James Webb Space Telescope. One was widely reported: that after a complex two-week process, the telescope extends it without any difficulty. Next steps towards more conventional scientific processes.
The other news, which is not well covered but is still significant, came to light during a news conference on Saturday. Mike Menzel, a mission systems engineer for NASA’s Webb Telescope, said the agency has completed its analysis of how much “extra” fuel is left on board the telescope. Roughly, Menzel said, Webb has enough propellant on board for a useful life of 20 years.
That’s twice the conservative pre-launch estimate for Webb’s decade-long life, in large part due to the performance of the European Ariane 5 rocket that launched Webb on a precise trajectory on Christmas Day.
Before launch, the telescope was fed 240 liters of hydrazine fuel and a dinitrogen oxide oxidant. Some of that fuel was needed to adjust the trajectory throughout the flight to a stable point in space, about 1.5 million kilometers from Earth, where Webb would make scientific observations. The remainder of Webb’s final orbit around the Lagrange stable point will be used to support the station and maintain its orbit.
So every kilogram of fuel saved on Webb’s trip to Lagrange Point could be used to extend his life there. Given that ten years seemed like a fairly short operational period for such an expensive and capable space telescope, NASA was already considering a costly and risky robotic refueling mission. But now this shouldn’t be necessary, as Webb is at least two decades old.
Much of this is due to the estimated performance of the Ariane 5 missile. NASA and the European Space Agency reached an agreement more than a decade ago that Europe would use the reliable Ariane 5 rocket to fly the telescope into space and, in exchange, European scientists would have time to use the telescope.
During an interview with interplanetary podcast, Ariane 5 program director Rudiger Albat explained how European rocket scientists approached the Webb launch. Each Ariane 5 is interchangeable, but the engineers and technicians involved in producing the missile know the components that work with any missile. So when they were building a Webb part, the engineer might say, “I’m going to take a second look” to make sure the part is the best it can be.
Ariane 5 also selected the best Webb components based on pre-flight testing. For example, for the rocket destined for Webb, the program used a main engine that was particularly accurate during testing. “It was one of the best Vulcan engines we’ve ever made,” Albat said. “His acting is very meticulous. It would have been criminal if I hadn’t done it. “
A similar attitude was taken towards other components, including the solid rocket engines that were used to build the Ariane 5 rocket launched two weeks ago.
Albatt admitted that the days leading up to launch were stressful and harrowing. But shortly after launch, Albatt said he and the entire European space community could be proud when Webb flies in and starts to lift his wings. He now he said, “I feel completely comfortable.” The same can be said for the many scientists who have been monitoring Webb’s evolution for two decades.