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Astronomie - NASA Webb Telescope Start 2021 - Update-16

14.11.2019

A milestone payload for Ariane 5: the James Webb Space Telescope is prepared for liftoff with Arianespace

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Technicians and engineers work to fully deploy the James Webb Space Telescope’s tennis court-sized sunshield at Northrop Grumman’s Redondo Beach, California facilities. Credits: NASA/Chris Gunn

With multiple pre-flight milestones achieved in recent months, the James Webb Space Telescope (JWST) – which will succeed the Hubble Space Telescope – is on course for its historic launch by Arianespace on an Ariane 5.

As the world’s premier space science observatory, the JWST will solve mysteries of the solar system, look for distant worlds, and probe the mysterious structures and origins of the universe. It is an international project led by the U.S. National Aeronautics and Space Administration (NASA) – along with its partners, the European Space Agency (ESA) and Canadian Space Agency (CSA).

Arianespace is performing the launch on behalf of ESA, within the agency’s scope of its collaboration with NASA. The mission – currently planned for 2021 – underscores Arianespace’s ability to serve institutional clients while also expanding humankind’s knowledge of the universe to make life better on Earth.

After deployment by Ariane 5 from the Spaceport in French Guiana, the JWST will travel to near the second Lagrange point (L2) of the Earth-Sun system (1.5 million kilometers from Earth, directly opposite the Sun), where the telescope will circle about the L2 point in a halo orbit.

Fully assembled for launch

Kicking off a series of launch preparation achievements, the two components comprising the JWST – the spacecraft and its telescope – were integrated for the first time in late August. This activity took place at the Redondo Beach, California facilities of U.S.-based Northrop Grumman, which leads the JWST industry team.

After the JWST was mechanically connected, engineers worked to electrically link up its two components – enabling them to “speak” to each other like they will in orbit. This optional risk reduction test, marked in late September, took advantage of an opportunity to electrically connect the two components months earlier than planned.

If any issues had been found during the evaluation, it would have given engineers more time to investigate and troubleshoot. In addition, this test provided a jumpstart for the separate spacecraft and telescope teams to begin working jointly as they will when the JWST is fully completed.

A milestone deployment

In October, the JWST passed a test critical to preparing the observatory for its 2021 Ariane 5 launch from French Guiana: deployment of its sunshield, which will protect the JWST’s mirrors and scientific instruments from light and heat while in orbit.

Shaped like a kite and sized at 22 X 10 meters, the sunshield’s five layers were fully deployed (and put under tension) during this continued activity at Redondo Beach, as engineers and technicians successfully put the sunshield into its operational position.

After the sunshield is returned to its stowed position for flight, the JWST will undergo comprehensive electrical tests, as well as a set of mechanical evaluations to simulate launch vibrations. There will be one final deployment and stowing cycle on the ground before its integration on Ariane 5.

Quelle: arianespace

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THE JAMES WEBB SPACE TELESCOPE TEAM

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The National Aeronautics and Space Administration (NASA) leads an international partnership that includes the European Space Agency and the Canadian Space Agency. NASA’s Goddard Space Flight Center is managing the Webb Telescope project, and the Space Telescope Science Institute is responsible for science and mission operations, as well as ground station development.

As the prime contractor to develop the James Webb Space Telescope, Northrop Grumman will design and build the deployable sunshield, provide the spacecraft and integrate the total system. The observatory subsystems are developed by a Northrop Grumman-led team with vast experience in developing space-based observatories:

  • Ball Aerospace: Optical design, mirrors, wavefront sensing, and control design and algorithms
  • Harris Corporation: Optical telescope integration and testing
  • University of Arizona: Near-Infrared Camera
  • European Space Agency (ESA): Near-Infrared Spectrograph
  • Jet Propulsion Laboratory (JPL), ESA: Mid-Infrared Instrument
  • Canadian Space Agency (CSA): Fine Guidance Sensor with Tunable Filter Module

THE JWST ENGINEERS

The Northrop Grumman engineers behind the James Webb Space Telescope have no easy task. It has taken one hundred million hours of people’s lives to build the largest, most complex and powerful space telescope ever built. Hear from the engineers who take pride in what they’re accomplishing — writing the next chapters of space history.

Learn more »

 Quelle: Northrop Grumman
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Update: 20.11.2019
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ZURBUCHEN HINTS AT MORE JWST DELAYS

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The head of NASA’s Science Mission Directorate hinted today that more delays may be in the offing for the James Webb Space Telescope (JWST).  While progress is being made integrating the spacecraft and its instruments at prime contractor Northrop Grumman, Thomas Zurbuchen is worried about the time it is taking and an agency-level assessment is underway to determine whether the March 2021 launch date is realistic.

 

Zurbuchen provided an update on JWST to the Science Committee of the NASA Advisory Council (NAC) this morning.  He recently visited Northrop Grumman and was impressed at the magnitude of the effort required to build the telescope, which is often described as the follow-on to the Hubble Space Telescope.  JWST and Hubble study the universe in different bands of the electromagnetic spectrum (Hubble is primarily an optical telescope while JWST operates in the infrared), but both are designed to unravel the mysteries of the universe.

Illustration of the James Webb Space Telescope (JWST). Credit: NASA

Originally envisioned in the late 1990s as a $1 billion telescope, by last year the cost had grown to $8.8 billion for development (not including operations).  That breached a congressionally-imposed cost cap of $8 billion that was established in law after substantial cost growth and schedule delays in the early part of this decade.  After rebaselining the program in 2011, NASA promised the telescope would launch in October 2018, but by late 2017 it was clear that date would not be met due to integration problems at Northrop Grumman.

NASA established an Independent Review Board (IRB), chaired by Tom Young, that concluded  the earliest possible launch date was March 2021.  NASA calculated the new development cost estimate at $8.803 billion, a 10 percent increase, which is surprising so late in a program.  Adding in operations, the revised life cycle cost is $9.663 billion.  The costs do not include launch.  The European Space Agency agreed to launch JWST on an Ariane V rocket as part of a cooperative agreement with NASA at no cost to NASA. Canada is also a partner in the project.

The House Science, Space, and Technology Committee held a two-day hearing following the IRB report where Northrop  Grumman bore the brunt of the committee’s displeasure.  In the end, however, Congress increased the cap to $8.8 billion considering that $7 billion had been spent already and the scientific potential of the data JWST will produce is indisputable.

The mantra became “Webb is worth the wait.”

The IRB report spelled out what had gone wrong and what needed to be done to ensure the telescope works properly once it is launched.  There are no second chances for JWST.  Unlike Hubble, JWST is not designed to be serviced by astronauts (or robots) and will not be located in Earth orbit.  It is headed to the Sun-Earth L2 Lagrange point 1 million miles (1.5 million kilometers) away.

That was Zurbuchen’s point this morning.  In a recent visit to Northrop Grumman where JWST passed a sunshield deployment test, he was impressed at the progress being made, but cited “close to a dozen issues that we’re working.”

“My worry at this moment in time is just the time we’re taking. … Our March ’21 launch date is the launch date that we’re heading towards and we’re currently in the process of our agency-level assessment of that to really see how likely that launch date is and … beyond that, financial reserves and so forth.

I know if you are an astrophysicist you want us to absolutely test this spacecraft absolutely well [and not] launch in March [2021] with problems.  —  Thomas Zurbuchen

 

 In an email this afternoon, a NASA spokesperson told SpacePolicyOnline.com that although “issues have been revealed during testing that have reduced the schedule margin,” NASA continues to work towards the March 2021 launch date. “Mission success depends on rigorous testing.”  NASA is “confident” in the success of JWST and there are no plans to reconvene the Independent Review Board.

Quelle: SPACEPOLICYONLINE.COM

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