Development
JWST is the maturation of the aforementioned Next Generation Space Telescope (NGST) plans. Some previously floated concepts include 8 meter aperture, 3 AU orbit, and NEXUS precursor telescope mission. A focus on the near to mid-infrared was preferred for three main reasons; high-redshift objects have their visible emissions shifted into the infrared, cold objects such as debris disks and planets emit most strongly in the infrared, and this band is very hard to study from the ground, or by existing space telescopes such as Hubble.
JWST has a planned mass about half of Hubble, but its primary mirror (a 6.5 meter diameter gold-coated beryllium reflector) has a collecting area about five times larger (4.5 m2 vs. 25 m2). The JWST is oriented towards near-infrared astronomy, but can also see orange and red visible light as well as the mid infrared region, depending on the instrument.
Early development work for a Hubble successor between 1989–1994, led to the Hi-Z telescope concept, a fully baffled 4 meter aperture infrared telescope going out to 3 AU in its orbit. The distant orbit helped reduce light noise from zodiacal dust. In the "faster, better, cheaper" era in the mid-1990s, NASA leaders pushed for a space telescope with low-cost and 8 meter primary mirror diameter. The result was plans for a NGST for $500 million, 8 meter aperture, and located at L2. By 2002, as the concept matured into more of a technical reality, it was reduced to 6 meters aperture and the cost was estimated at around $2.5 billion
Some concepts from early in development are:
- Goddard Space Flight Center design for JWST
- Ball Aerospace design for JWST
- Lockheed Martin design for JWST (Phase A winner)
- TRW design for JWST (Phase A winner and selected as prime contractor).
In 2002, TRW was bought by Northrop Grumman.
Read more about this topic: James Webb Space Telescope
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