Quick Facts About Webb


Webb's mirror
A marble-sized piece of beryllium. Webb's mirror is constructed of this lightweight metal.
An Ariane 5 rocket will carry Webb into space.

Mirror Type: Segmented parabolic reflector

Width: 21.6 feet (6.5 m) at its widest point

Area: 269 square feet (25 m2)

Mass: 1554 lbs (705 kg)

Focal Length: 414.4 feet (131.4 m)

Optical Resolution: 0.07 arc-seconds, diffraction-limited at 2-micrometer wavelengths (0.0317 arc-second pixels)

Material: Beryllium, with a thin coating of gold

Number of Segments: 18

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Operating Temperature: –387.7 Fahrenheit (40 Kelvin; –233.2 Celsius)

Observatory Mass: About 14,000 lbs (6,330 kg)

Sunshield Size: 70 by 48 feet (21.2 by 14.6 m)

Planned Launch: 2018

Launch Vehicle: Ariane 5 rocket, provided by the European Space Agency

Launch Site: The Centre Spatial Guyanais (CSG) in Kourou, French Guiana

Location: Orbiting the Sun 940,000 miles (1.5 million km) from Earth at the Second Lagrange Point (L2)

Orbit Shape: As seen from Earth at midnight, the Webb orbit completes a large loop of 1,000,000 km in diameter, twice a year.

Transit Time to Orbit: About 1 month

Science Mission Lifetime: 5 years, with a goal of 10 years

Solar Array Power: 2000 watts

Maximum Data Rate (Deep Space Network): 28 Mbps

Cost at Launch: $8 billion, plus ESA and CSA contributions

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Wavelength Coverage: 0.6- 28.5 micrometers

Instruments: 4

  • Near Infrared Camera (NIRCam) (0.6–5 micrometers)
  • Near Infrared Spectograph (NIRSpec) (0.7–5 micrometers)
  • Mid Infrared Instrument (MIRI) (5–28.5 micrometers)
  • Fine Guidance Sensors/Near-Infrared Imager and Slitless Spectrograph (FGS/NIRISS) (0.6–5 micrometers)

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Webb's sunshield is the size of a tennis court.

Webb's mirror is covered in a thin layer of gold.

While Webb can't observe Mercury or Venus, it will be able to study the solar system beyond the orbit of Mars, including Mars, the outer planets, icy moons, and Kuiper Belt Objects.

Excepting rare glints from the Sun, the Webb will appear as a very faint star in the night sky when seen from the Earth, more than 10,000 times fainter than the faintest star seen by the naked eye.

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