Webb Launch Coverage
The James Webb Space Telescope Has Left Earth
“The James Webb Space Telescope is safely in space, powered on and communicating with ground controllers. Webb continues in coast phase, and is now oriented correctly with respect to the Sun. At approximately 30 minutes after launch, Webb’s solar array began to open up. It is now fully deployed and we have confirmed that the spacecraft is power positive.”
James Webb Space Telescope Launch Replay
Pre-launch
Post-launch
Wonderful news and a big sigh of relief from me! I know mistakes were made and money and time was wasted, but now I can hope for the best.
Making the Webb serviceable would have been a much safer and productive approach. Getting to L2 will eventually become achievable for a service mission. All that money for a 5 year mission life – limited by fuel that could be replenished.
The engineering mission life requirement is typically much shorter than the actual mission life. I’m sure Hubble wasn’t spec’d with a 30-year requirement.
That 5 years is a minimum. The max is 10 years when the fuel for the thrusters is expected to run out.
Not sure where the five year number is coming from. Prior to the launch Keith Parrish who is the senior engineer for JWST said that a very conservative estimate is ten years of fuel. And he said that number is based on an almost worst case scenario where a combination of things go wrong such as Ariane 5 underperforming by a significant amount, and the 12.5 hour MET burn (the only one that is time critical) is delayed for some reason, and several other things go off nominal. But he said if there are no such problems the fuel could easily last twenty years, although an actual prediction is somewhat complex.
As it turned out Ariane 5 delivered what appears to be an almost perfect insertion for altitude, inclination and speed. And the first mid-course correction burn went off on time at 7:50 pm EST.
But yes I realize other things can still go wrong. The serviceability issue has been widely discussed. The decision was not as easy as it sounds, especially at the time when they made it.
A five year lifetime is the design requirement. I believe ten years is the goal but not the requirement. It looks like they’ll achieve that goal, but the five year requirement is still in a lot of documents and references.
Thanks. Although the comment that I was replying to seemed to suggest that the five year limitation was because of fuel. Parrish made a point to mention during his answer that he was only talking about mission life in terms of fuel (that’s the specific question that he was asked).
I would think a similar method is used to determine the overall mission life estimate. I don’t remember what mission it was but one of the project leaders said that they try to come up with worst case scenarios to determine what could be thought of as minimum expected mission life, with the goal that all of the primary science objectives can be met during that time. Even though they expect that not everything is going to go wrong and most likely the mission will last much longer than that.
According to this article:
https://arstechnica.com/sci…
the Arian performance and the first MCC burn were so good that NASA says there will be enough fuel to last more than 10 years.