Webb Ground Segment Integration and Test: Preparation for Launch

Paul Lee (plee[at]stsci.edu), Christopher Hanley (chanley[at]stsci.edu), Ariel Bowers (abowers[at]stsci.edu), and Mark Abernathy (abernathy[at]stsci.edu)


The Webb Integration and Test Program is working hard to bring the ground system and the flight hardware, including the Science Instruments, Integrated Science Instrument Module (ISIM), and Optical Telescope Element (OTE), together for the mission. This article summarizes the milestones successfully reached thus far by the OED I&T team, and we highlight the upcoming activities leading up to the launch of Webb.

What is Integration and Test (I&T) and why is it important?

Take the development of a new car. Many different parts and components have to be designed, developed, built, and tested. Teams of engineers are involved in crafting these parts, but the collection of parts and components does not automatically become a car.  That collection of parts cannot drive you from point A to point B. The I&T team, in collaboration with System Engineering and Development, has the responsibility to assemble the parts into the final product, and to make the sum of the parts work together as an integrated whole.

A key responsibility of the Operations and Engineering Division (OED) I&T Team is to integrate the Webb Ground Segment. The team works meticulously throughout the I&T process to bring separate systems together from end to end, resolving issues and problems along the way. The team often serves as pioneers as they are the first to operate the latest integrated Ground Segment as a whole. These campaigns verify and validate system interfaces by exercising, for the first time, data flowing among different sites, communication networks, different software systems, and human operator workflows.

Preparing for the launch of the James Webb Space Telescope

As we approach the launch of the James Webb Space Telescope, the OED I&T team has been actively involved on a number of fronts, bringing the instruments and the ground system together for the mission. For the past several years the spacecraft and instrument hardware I&T has been the main focus. The OED I&T team supported the integration and testing of the science instruments and the ISIM at the Goddard Space Flight Center (GSFC), as well as the OTIS (Optical Telescope Element + Integrated Science Instrument Module) thermal vacuum testing at the Johnson Space Center (JSC).

At the Institute, the I&T team has been busy testing the various software subsystems of the Science and Operations Center (S&OC) and the integration of these subsystems together into the larger Webb ground system. In the fall of 2017, engineers delivered the second release of the ground system software for the Webb S&OC and successfully interfacing it with other external facilities such as the Deep Space Network (DSN). At present, the I&T team continues to test and integrate newer software releases into the S&OC, and we are also integrating and testing the backup Mission Operations Center (bMOC) at GSFC to ensure operation continuity should the primary MOC at the Institute become unavailable.

Webb’s state-of-the-art Flight Control Room (FCR) resides inside the Mission Operations Center (MOC), located at the Space Telescope Science Institute in Baltimore, MD.

The milestones we have reached thus far…

We have completed the following campaigns:

  • Science instrument cryovac testing at GSFC
  • OTIS thermal vacuum testing at JSC
    • Provided on and off console support for OTIS test activities and the science instrument cryovac testing
  • S&OC subsystems I&T
    • Completed requirement and discrepancy testing for 16 builds of the Proposal Planning Subsystem (PPS), 8 builds of the Data Management Subsystem (DMS), 7 builds of the Wavefront Sensing Subsystem (WSS) and 3 builds of the Flight Operations Subsystem (FOS)
  • S&OC Release 1 & 2
    • Completed verification and validation acceptance testing of the integrated S&OC witnessed by the Government
  • Ground Segment (GSEG) #1
    • Completed ground segment verification testing of the S&OC and spacecraft interfaces
  • Initial data flow tests through various external interfaces, such as the Space Network (SN), Deep Space Network (DSN), Flight Dynamics Facility (FDF), and Observatory simulator at Northrop Grumman Aerospace Systems (NGAS)
    • Completed over 50 End-to-End data-flow verification and validation tests

What are the upcoming milestones (as of early March 2018)?

  • SOC Release 2.0.1 with various new subsystem builds – April 2018
    • Complete additional verification and validation acceptance testing of the integrated S&OC witnessed by the Government
    • This version of the S&OC enhances the end-to-end data flow of the system
  • SOC Build 4.2 with various new subsystem builds – Winter 2018
    • Complete additional verification and validation testing of the integrated S&OC
    • This version of the S&OC will be used in testing with the Observatory during GSEG #3 and #4
  • S&OC to Spacecraft test (GSEG #2) – August 2018
    • Completes ground segment verification testing of flight to ground requirements
  • Integrated Observatory with the S&OC (GSEG #3) – December 2018
    • GSEG #3 is the formal end-to-end validation test of the integrated Observatory with the Ground Segment
  • Final Observatory to S&OC test (GSEG #4) – February 2019
    • GSEG #4 is the final integrated Observatory test with the "Flight Build" of the S&OC
  • End-to-End test between the S&OC, SN, DSN, FDF, and NGAS – through launch
    • As new versions of S&OC systems and the systems used by our external partners are updated, we continue testing to ensure the ground segment remains operational
  • Launch site to S&OC interface test – Launch – 3 months
    • A test of the ability of the S&OC to communicate with the Webb Launch Site

The Integration and Testing of the Webb Ground Segment and the S&OC

Multiple teams with diverse expertise and experience contribute to the integration and testing of the Webb S&OC. Composed of members from Science Operations, Flight Operations, Systems Engineering, Information Technology Services Division, Development and the I&T Branch, this "Team of Teams" works together with professionalism, integrity, and mutual respect to successfully complete many integration and test campaigns. The execution of these campaigns required careful planning and coordination among the Institute teams, external partners, and stakeholders at different geographic locations across different time zones. Together, the team successfully verified and validated the systems. Furthermore, the many Government-witnessed campaigns firmly validated the functionality and operability of the integrated system to the key stakeholder, successfully reaching the appropriate level of system maturity.