NASA’s Webb “Pathfinder Telescope” Successfully Completes First Super-Cold Optical Test

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Testing is essential partial of NASA’s success on Earth and in space. So, as a tangible moody components of NASA’s James Webb Space Telescope come together, engineers are contrast a non-flight apparatus to safeguard that tests on a genuine Webb telescope after goes safely and according to plan. Recently, a “pathfinder telescope,” or usually “Pathfinder,” finished a initial super-cold visual exam that resulted in many first-of-a-kind demonstrations.

The Pathfinder was pushed into a Chamber for OGSE2. Credits: NASA/Chris Gunn

The Pathfinder was pushed into a Chamber for OGSE2.
Credits: NASA/Chris Gunn

“This exam is a initial dry-run of a apparatus and procedures we will use to control an end-to-end visual exam of a moody telescope and instruments,” pronounced Mark Clampin, Webb telescope Observatory Project Scientist during NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It provides certainty that once a moody telescope is ready, we are entirely prepared for a successful exam of a moody hardware.”

The Pathfinder is a non-flight reproduction of a Webb telescope’s core territory backplane, or “backbone,” that includes mirrors.

The moody backplane comes in 3 segments, a core territory and dual wing-like parts, all of that will support vast hexagonal mirrors on a Webb telescope. The trailblazer usually consists of a core partial of a backplane. However, during a test, it hold dual full distance gangling primary counterpart segments and a full distance gangling delegate counterpart to denote a ability to optically exam and align a telescope during a designed handling temperatures of -400 degrees Fahrenheit (-240 Celsius).

The initial cryogenic visual contrast of a Pathfinder was successfully finished in Chamber A during NASA’s Johnson Space Center in Houston, Texas. Chamber A was creatively used to exam a Apollo capsule. This exam demonstrated new helium and nitrogen cooling systems commissioned for a Webb telescope contrast that authorised a Pathfinder to grasp those wintry heat that will copy handling temperatures we will have during a L2 Lagrange point. The cooling complement is commissioned in a chamber.  There is a opening cover with a nitrogen hide inside of it and afterwards a helium hide inside of a helium shroud. The Pathfinder is afterwards inside a Helium shroud.

“The many poignant breakthrough was a first-ever cryogenic visual fixing and contrast of mixed primary counterpart segments in a routine famous as ‘phasing,’” pronounced Lee Feinberg, Webb telescope Optical Telescope Element Manager during NASA Goddard.

“During a demonstration, mirrors that were primarily misaligned by millimeters were aligned to any other regulating actuators handling during -400F to improved than one-one-thousandth hole of a tellurian hair (or a fragment of a wavelength of light) such that a dual primary counterpart segments were optically homogeneous to a singular monolithic mirror,” Feinberg said.

The second “first” concerned a straight course of a contrast of a mirrors. It noted a initial time a lightweight cryogenic counterpart of this form had been tested in a second sobriety orientation. “To know a second sobriety orientation, consider of a cup,” Feinberg said. “When a crater is face adult so we can flow H2O in it, it is straight to gravity. Now put a crater on a side and it is plane to gravity. Mirrors are like cups in this explanation.” That authorised for successful cross-checking of a likely zero-gravity opening of a mirrors.

“In another vital achievement, 4 vast super cold windmills carrying steerable cameras were means to magnitude a fixing of all of a mirrors and structure to improved than one-tenth of a millimeter regulating a routine called photogrammetry,” Feinberg said. Photogrammetry is a technique that takes images from mixed to copy handling temperatures orientations, combines those images, and afterwards regulating triangulation algorithms to establish distances between objects in those scenes.

The phasing proof used a new metrology device grown for NASA to exam segmented telescopes by 4D Technologies Corporation called a multi-wavelength interferometer and used a contemplative nothing lens designed and built by Harris Corporation.

After this exam completed, a moody Aft Optics System, that includes a Tertiary Mirror and Fine Steering Mirror, was commissioned on a Pathfinder to prepared for a second test. The full Pathfinder was afterwards given with special fiber-fed infrared visual sources that copy star images. Those star images, or infrared sources, along with a specifically instrumented infrared detector will be used during a second exam to perform end-to-end contrast of a full Pathfinder telescope complement and safeguard they duty as unnatural stars.

After that second exam is finish late in 2015, all visual exam systems will have been checked out.

A third and final predecessor exam called “Thermal Pathfinder” will follow in 2016 that will entirely exam all a exam apparatus indispensable to copy a heat sourroundings of space.  Once this is complete, all exam apparatus and procedures indispensable to exam a tangible full moody telescope and a Integrated Science Instrument Module or ISIM built as a section in early 2017 will be checked-out and ready.

Orbital ATK built a combination structure of a trailblazer backplane. The trailblazer (minus a mirrors) was tested during Northrop Grumman in Redondo Beach, California

The James Webb Space Telescope is a systematic inheritor to NASA’s Hubble Space Telescope. It will be a many absolute space telescope ever built. Webb is an general plan led by NASA with a partners, a European Space Agency and a Canadian Space Agency.

Source: NASA