The Evolution Of Life
Space Telescopes in The News
There have been recent news stories concerning both the Hubble Space Telescope and the James Webb Space Telescope. Both telescopes are historic in their time. The James Webb Space Telescope has recently sent photographs of the earliest galaxies ever seen – almost to the beginning of time.
Hubble Space Telescope
The Hubble Telescope was launched in 1990 and orbits in Low Earth Orbit (LEO) at an altitude of approximately 332 miles. This orbit is above Earth’s interfering atmosphere and below the Van Allen Radiation Belts. The Van Allen Radiation Belts offer some protection to the telescope.
Hubble’s orbit in LEO offers another advantage: it can be serviced in orbit. The first servicing mission was in 1993 to repair a flawed mirror. Had that or later missions not been possible the telescope would remain unable to fulfill its purpose. In all, there have been 5 Repair-Upgrade launches to the Hubble Space Telescope. The missions have added to the telescope’s useful life and improved its capabilities.
The last servicing mission to the Hubble was in 2009. That mission installed what is called the ‘Soft Capture Mechanism’. For this servicing, the telescope was placed within the Space Shuttles Payload Bay. The Soft Capture Mechanism is intended as an attachment point for a future robotic rocket that can either boost the telescope to a higher orbit or place it in a safe re-entry trajectory where it will burn up in the Earth’s atmosphere.
One of Hubble’s most famous pictures is the pillars of gas and dust in the Corina Nebula known as ‘The Pillars of Creation’. The telescope, however, is limited in magnifying power because it had to fit within the rocket fuselage, thus restricting mirror size. Another limitation was expressed in the news recently. Space debris sometimes streaks across a photo image ruining it. With all the ‘space junk’ in LEO and with the added numbers of SpaceX Starlink Satellites in orbit, this is becoming a serious problem.
James Webb Space Telescope
The James Webb Space Telescope launched on December 25, 2021, into a high orbit around the Sun called the Earth-Sun L 2 Lagrange point. This orbit is about 1.5 million kilometers (930,000 miles) away from Earth. The telescope is 6X more powerful than Hubble with almost half the mass of Hubble. This is possible because of improvements in technology, principally smaller and more capable electronics. The vastly increased size of the mirrors was made possible by designing an origami-like folding of the mirror panels. Unfolding and focusing the mirrors were mission-critical functions that worked perfectly. The Solar Heat shield is also deployed correctly to protect the mirrors from the Sun.
James Webb can ‘see’ almost to the beginning of time. It has produced a stunning photograph of the earliest galaxies ever seen. The telescope is revealing new previously impossible details of the universe with its infrared cameras. However, as perfectly as it is operating there are concerns. The extreme distance of the telescope places it far above interference from ‘space junk’, but makes it impossible to service should something go wrong. The other concern is more of a limitation. The telescope used fuel to orient to a selected target and to make small adjustments to its orbit. Every use of the telescope then shortens its life.
Building Telescopes in Space
Astronomy will become much less costly and more available once we have the ability to manufacture large telescopes in space. This will only be done when humans have a permanent presence in space habitats.
With manufacturing capabilities in space, the need for massive rockets to launch from the Earth’s gravity well will no longer be a limitation. With a permanent human-robotic presence in space, a multitude of telescopes could be built and maintained. This would offer astronomers far greater viewing time on ever larger portions of the universe. It will be a glorious day if and when we ever achieve it.