All waiting for the launch of the James Webb Space Telescope (JWST) on 18 December 2021
JWST will be launched on Saturday, 18 December 2021 (between 8.45 p.m. and 11.00 p.m., Malaysian Time) from the Arianespace EL3-A launchpad at the Guiana Space Centre, in Kourou, French Guiana.
After a 16-day and 9,300 km journey by ship from Los Angeles (Pacific Ocean), the JWST passed through Panama Canal and arrive in Kourou, French Guiana, South America (Atlantic Ocean).
The end of the era for the Hubble Space Telescope (HST) is approaching. HST can observed in the ultraviolet, visible and near-infrared wavelengths. JWST can observe in the infrared wavelengths from 0.6 to 28.3 microns wavelengths. This means that JWST can see further into the universe and closer to the Big Bang Explosion than HST.
The operators for JWST are NASA, ESA and Space Telescope Science Institute (STScI)
The cost for JWST is USD 10 Billion. It is a Korsch Telescope. The primary mirror is 6.5 meter in diameter and is made up of 18 concave segments of hexagonal beryllium mirrors that are vacuum coated with a thin layer of gold. The 0.74 convex secondary mirror and the tertiary mirror are also made of beryllium and coated with gold. The advantages of beryllium are that it is three times lighter than aluminium and six times stronger than steel and beryllium can work well at -233oC (40K), which is the working temperature of the JWST. JWST has an effective f/16.6 and focal length of 131.4 m. A distinguishing feature of JWST is that during launch, the telescope with its 18 segments primary mirror can be folded into a smaller volume inside the payload area of Ariane 5 Rocket. After being launched into space, the various parts of the primary mirror can be unfolded to achieve the final diameter of 6.5 m.To maintain the working temperature for JWST, a five-layer sunshield made up of Kapton polyimide layers as large as a tennis court will unfurl in space to provide a permanent shade from sunlight and maintain a permanent working temperature of -233oC for JWST. This low temperature is essential to reduce the infrared radiation from the primary mirror itself from affecting the infrared signals from the astronomical objects as observed by JWST. The mass of JWST is 6,500 kg which is half the mass of HST.
JWST’s primary aim is to shed light on our cosmic origins: it will observe the Universe’s first galaxies, reveal the birth of stars and planets, and look for exoplanets with the potential for life. JWST can see far away objects that are only 200 million years from the Big Bang Explosion whereas HST can see objects that are 480 million years from the Big Bang.
The four scientific instruments in the JWST are:
- Mid-Infrared Instrument
- Near-Infrared Camera
- Near-Infrared Spectrograph
- Near-Infrared Imager and Slitless Spectrograph/Fine Guidance Sensor
After launch, the JWST will be placed in the Sun-Earth L2 Lagrangian Point which is a semi-stable gravitational halo orbit that is 1.5 million km from the Earth in a direction away from the Sun. From time to time, small thrusters in the JWST will fire to reduce the drift of the telescope and bring it back into its more stable orbit.
From the time of launch on 18 December 2021 to full deployment of all the systems in JWST when it arrives at the L2 Lagrangian Point, it will take 30 days. This will be followed by another six months of testing of all the instruments and systems of JWST before this great telescope can start transmitting its first images and data back to humanity on Earth. We hope the launch and all subsequent events for JWST goes well according to plan and in the years to come when we speak about great astronomical discoveries, it will no more be about;
Hubble, Hubble and Hubble and instead will be Webb, Webb and Webb!!!
Article by Dr Chong H.Y.
Source from NASA JWST website: https://www.jwst.nasa.gov/
