Webb Space Telescope Unlikely to Meet Launch Schedule

Deployment tests like these help safeguard mission success by physically demonstrating that NASA’s James Webb Space Telescope is able to move and unfold as intended. (Credits: NASA/Chris Gunn)

by Douglas Messier
Managing Editor

In the latest not shocking, totally expected news out of Washington, NASA’s troubled James Webb Space Telescope (JWST) has a very low chance of meeting its March 2021 launch date.

Exactly how low? Twelve percent.

That means the chance of JWST not making the launch date is….well, you do the math.

That’s the word from the Government Accountability Office (GAO), which last week published its latest review of NASA’s major projects.

GAO completed its report prior to the point at which the COVID-19 pandemic slowed work on the giant telescope and NASA’s other major projects.

The government watchdog did have some good news, however.

“Project officials noted that cost reserves were adequate to extend the launch date by 3-4 months, if necessary, and that they would reexamine the launch date prior to the pre-environmental test review in spring 2020,” the report stated.

Credit: GAO

Those additional cost reserves resulted from a June 2018 re-plan that added 29 months to the schedule and $828 million to the project’s budget, which rose to nearly $9.7 billion. The project was based lined at just under $5 billion in 2009.

GOA reports that engineers have encountered a number of issues since the June 2018 re-plan that have eaten into schedule reserves. Those issues have included:

  • two spacecraft parts needed to communicate data with ground control that failed during testing;
  • repairs needed on stabilizing flap;
  • design changes to prevent damage to the spacecraft’s enormous sun shield; and,
  • 501 bolts installed in the telescope that don’t meet specifications.

GOA’s assessment of the JWST follows.

NASA: Assessments of Major Projects
Report to Congressional Committees

Government Accountability Office
April 2020

James Webb Space Telescope

The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope designed to help understand the origin and destiny of the universe, the creation and evolution of the first stars and galaxies, and the formation of stars and planetary systems. It will also help further the search for Earth-like planets.

JWST will have a large primary mirror composed of 18 smaller mirrors and a sunshield the size of a tennis court. Both the mirror and sunshield are folded for launch and open once JWST is in space. JWST will reside in an orbit about 1 million miles from the Earth.

Project Summary

The project recently conducted a cost and schedule analysis, which indicated a 12 percent confidence level in achieving the current committed launch date of March 2021. However, the program has reported that planned funding and cost reserves are adequate to extend the schedule to launch by 3-4 months.

Though the project has completed several integration and testing milestones, technical challenges have significantly reduced the amount of schedule reserves available to accommodate new risks identified during observatory integration and testing. For example, anomalies with two spacecraft parts needed to communicate data with ground control occurred during testing.

Though NASA and the contractor have taken steps to recover schedule, the project must enter the final phase of testing, which includes another set of challenging environmental tests, with diminished schedule reserves. The project has already identified repairs needed for a stabilizing flap and the replacement of certain bolts as potential schedule risks going forward.

Cost and Schedule Status

Technical challenges since the JWST program’s last replan have strained schedule and NASA has assessed the likelihood of meeting its March 2021 launch date to be relatively low. In June 2018, NASA established a new life cycle cost commitment of $9.7 billion and launch readiness date of March 2021—$828 million over and 29 months later than the baselines established by the project’s previous replan in 2011.

Though the replan replenished schedule reserve at a level greater than indicated by the center policy, technical challenges during spacecraft testing in 2019 required the project to use reserves faster than planned. Following these issues, the project completed a joint cost and schedule confidence level analysis in October 2019 that found the project had a 12 percent likelihood of meeting its revised launch date.

As of February 2020, the project reports that it has 56 days, or about 16 percent, of its replenished schedule reserves left. Project officials noted that cost reserves were adequate to extend the launch date by 3-4 months, if necessary, and that they would reexamine the launch date prior to the pre-environmental test review in spring 2020.


The project has approved design changes to address previously identified risks to the sunshield including cable snags and damage that could occur when the launch vehicle’s fairing depressurizes in space.

However, anomalies with the command and telemetry processor and traveling wave tube amplifier—which will communicate science and command data—were the two largest contributors to the loss of schedule reserve. These components shut down unexpectedly during spacecraft element testing and efforts to determine the causes and potential solutions for the anomalies required 120 days, or about 41 percent, of the project’s replenished schedule reserves.

Officials stated that workmanship issues are the likely cause for at least one of the anomalies and have taken steps to mitigate risk to the observatory. For example, the project has received replacement amplifiers and is in the process of upgrading an engineering model processor to replace the faulty one aboard the observatory if necessary.

Integration and Test

The project completed testing on the individual component elements and integrated them to begin observatory level testing, the last of five phases of integration and testing in August 2019. However, the project must complete another set of challenging environmental tests now that the observatory has been fully integrated.

Our prior work has shown that integration and testing phase is when problems are most likely to be found and schedules tend to slip. The project is monitoring several technical issues and risks that could further affect the project’s schedule.

For example, the contractor determined on another program that certain bolts held in common with JWST did not meet specifications. JWST isolated the bolts but found that 501 were already installed on the observatory.

The project is performing strength testing but has not yet determined how many will need to be replaced. Further, the project is investigating structural and electrical issues related to the deployment of the sunshield.

Finally, the program must remove and make repairs to the spacecraft’s momentum flap, which will act as a balance against solar pressure that could cause unwanted movement in orbit, prior to beginning observatory-level vibration testing.