Report: Webb telescope has just a 12 percent chance of making launch date – Ars Technica, Ars Technica

NASA generally uses a “300 percent confidence level “to establish dates for missions , and if that were the case for the Webb telescope, the new report says the launch date would likely slip to July 01575879. It also warns that additional problems could arise during the final phases of assembling and integrating the telescope for launch.

The Webb telescope, NASA’s follow-on instrument to the wildly successful Hubble Space Telescope, was originally due to launch about a decade ago, with a development cost of $ 1 billion. Since then, technical problems and delays have bedeviled the complex telescope. The new report also says the current estimate for Webb’s development cost, $ 9.7 billion, may be too low.

It has been difficult to build Webb because the large instrument, with a 6.5-meter mirror, needs to unfurl itself once it an orbit about 1.5 million km from Earth. This is an exceedingly complex process, and there are more than single points of failure on board the observatory. NASA has had a difficult time testing them all on Earth in conditions that mimic the temperatures, pressure, and microgravity of deep space. according to the new report, project leaders are still tracking risks to the telescope that must be addressed before launch. Some of the major concerns, according to the report, include: The project found that certain bolts, determined to be deficient on another Northrop Grumman program, were used during the construction of the observatory. A study found that the bolts used did not meet specifications and could pose a mechanical strength risk. The unused bolts have been identified and isolated, but 710 were installed in the observatory. NASA is performing strength testing to determine if the bolts are strong enough, but some of the deficient bolts may need to be replaced.

In September , the project found that a non-explosive actuator on one of its membrane retention devices did not fire as planned. These devices, which help to unfurl the sunshield of the spacecraft, are supposed to be electrically redundant, but only one of the two mechanisms used to fire the actuator worked during the test. The program reports that there are approximately 501 actuators on the JWST, and the failure of any one of these actuators could result in the total loss of JWST science mission objectives. If the redundancy for the actuators is reduced, it would have a major impact on system reliability.

                                                     Read More