Webb telescope faces more schedule risks, engineering issues
Even as NASA touts the final assembly of the James Webb Space Telescope, its program director noted in a presentation that the telescope is still facing several engineering issues that could cause further launch delays.
They presently are targeting a March 2021 launch on an Ariane 5 rocket (ten years behind schedule). Their schedule cushion (the extra time built into their schedule in case they have problems) however has shrunk from nine months to only two. Worse, there remain several lingering unsolved engineering problems.
One such problem is with an electronics unit called a command telemetry processor that malfunctioned during environmental testing. Robinson said engineers had problems duplicating the problem to determine the root cause and plan to replace the unit, along with a traveling wave tube amplifier used in the spacecraft’s communications system that also failed during testing.
NASA has also been working with launch provider Arianespace about concerns that residual pressure within the payload fairing at the time of fairing separation could “over-stress” the sunshield membranes. Tests on recent Ariane 5 launches confirmed that there was a higher residual pressure than the sunshield was designed for. Vents in the fairing are being redesigned to address this, Robinson said, and will be tested on Ariane 5 launches in early 2020.
However, those smaller problems, along with bigger issues like fastener problems with the sunshield found during environmental testing last year, have eroded the margin built into the revised schedule for the mission.
Unmentioned in the article is the fact that Arianespace is planning to retire the Ariane 5 when its Ariane 6 starts launching next year. Right now they have agreed to maintain their Ariane 5 launch facilities through March 2021 to allow Webb’s launch, but further delays could cause significant problems, including fixing the fairing issue mentioned above. At a certain point Arianespace will no longer be willing to hold onto Ariane 5 for just this one launch.
Also unmentioned in the article is the status of Webb’s budget, which has grown from a proposed $500 million cost to almost $10 billion. I suspect that if they can meet their March 2021 launch date that total will not grow much. Any further delays however will once again cause it to balloon.
(I originally listed the proposed cost of Webb above as $1 billion, but that number is wrong. See the comments below).
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Even as NASA touts the final assembly of the James Webb Space Telescope, its program director noted in a presentation that the telescope is still facing several engineering issues that could cause further launch delays.
They presently are targeting a March 2021 launch on an Ariane 5 rocket (ten years behind schedule). Their schedule cushion (the extra time built into their schedule in case they have problems) however has shrunk from nine months to only two. Worse, there remain several lingering unsolved engineering problems.
One such problem is with an electronics unit called a command telemetry processor that malfunctioned during environmental testing. Robinson said engineers had problems duplicating the problem to determine the root cause and plan to replace the unit, along with a traveling wave tube amplifier used in the spacecraft’s communications system that also failed during testing.
NASA has also been working with launch provider Arianespace about concerns that residual pressure within the payload fairing at the time of fairing separation could “over-stress” the sunshield membranes. Tests on recent Ariane 5 launches confirmed that there was a higher residual pressure than the sunshield was designed for. Vents in the fairing are being redesigned to address this, Robinson said, and will be tested on Ariane 5 launches in early 2020.
However, those smaller problems, along with bigger issues like fastener problems with the sunshield found during environmental testing last year, have eroded the margin built into the revised schedule for the mission.
Unmentioned in the article is the fact that Arianespace is planning to retire the Ariane 5 when its Ariane 6 starts launching next year. Right now they have agreed to maintain their Ariane 5 launch facilities through March 2021 to allow Webb’s launch, but further delays could cause significant problems, including fixing the fairing issue mentioned above. At a certain point Arianespace will no longer be willing to hold onto Ariane 5 for just this one launch.
Also unmentioned in the article is the status of Webb’s budget, which has grown from a proposed $500 million cost to almost $10 billion. I suspect that if they can meet their March 2021 launch date that total will not grow much. Any further delays however will once again cause it to balloon.
(I originally listed the proposed cost of Webb above as $1 billion, but that number is wrong. See the comments below).
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Bob,
Speaking of massively over-budget government space programs, did you catch the latest article by Eric Berger at Ars Technica? It’s on what NASA is planning for the Artemis landings, and has this little bombshell:
“One of the limitations on returning samples is the Orion spacecraft, which will carry astronauts back from lunar orbit to Earth. Chavers said the Orion spacecraft does not have any designated space for a box of sample rocks taken from the lunar surface.”
So the deep-space moon ship wasn’t designed to haul moon rocks? Sheesh.
Scott M: I only glanced at that Ars Technica article, and then decided I had better things to do with my time than read NASA fantasies about a mission that almost certainly will not happen. Thus I missed this gem.
I shall post on the main page, and hat tip you!
From the article: “Most missions expect to use up schedule reserve as they progress towards launch. However, earlier this year Tom Young, who chaired the Independent Review Board chartered by NASA last year to review cost and schedule problems with JWST, warned that the mission appeared to be using up schedule reserve at a higher-than-expected rate.”
This higher than expected rate is without any major problems that have to be solved.
Also from the article: “A major problem, though, could wipe out that schedule reserve. ‘If we encounter a big problem, something really significant, that’s a semi-bad day, schedule-wise,’ [Greg Robinson] said.”
The semi-bad days are the ones that “that cost us a day, two or three days, a week.” That is where the schedule reserve is disappearing to. Webb is being “nickel and dimed” to death one small slip at a time, a death of a thousand paper cuts. If they keep having all these semi-bad days, then one of them will be the one where the launch schedule will have to slip and the cost will have to increase again.
That day will be a bad day, not a semi-bad one.
One can only wonder what science could have been funded and done, over the past couple of decades, had Webb been cancelled or hadn’t been funded at all, nine billion dollars ago.
Robert,
Please recall that the original concept was to cost half that original billion dollar budget:
https://behindtheblack.com/behind-the-black/points-of-information/nasa-wants-to-delay-wfirst-to-pay-for-webb-overruns/
“the original concept for the mission [Webb] called for it to cost $500 million and launch in 2007, versus a current lifecycle cost of $9.6 billion and launch in 2021. ‘This is 19 times the original cost and a delay of 14 years,’ said Rep. Lamar Smith (R-Texas), chairman of the committee. ‘It doesn’t get much worse than that.’”
Well, actually, it can get much worse. The original concept was for Webb and Hubble to work in concert and collect date from the same objects and nebula at or near the same time in order to compare and contrast their observations at their different wavelengths. It was one of the selling points for Webb. We have already lost a dozen years of such investigations, and another 18 months are on schedule to be lost.
Edward: Thank you for the reminder from my own website. I had forgotten about that testimony from Bridenstine.
Proposed by NASA: $500 million, to be launched in 2007.
Present situation: $9.6 billion, to be launched in 2021.
Anyone see a problem here?
It would have been cheaper to make it in space.
These continuing “semi-bad days” don’t bode well for reliability. Assuming that Webb ever launches, I will be surprised if it actually reaches operational status.