Monday, May 30, 2005

The future of the Hubble Telescope -- Part II

So, as promised, here are some arguments people have used against servicing the Hubble Space Telescop which I consider somewhat suspect. Some of these arguments have been put forward by people who should know better, such as high-level NASA people.
  1. Hubble is dying. This is a partial truth. If left alone, the Hubble telescope will die. But the Hubble was designed to be repaired -- many of its parts, such as the failing gyroscopes that are threatening Hubble now, have been replaced many times already. Although Hubble is sick right now, a successful repair mission will make it as good as new, and ready to serve out another 5-10 years before retiring.
  2. Hubble's replacement is being built right now, so there is no need to repair Hubble. This refers to the "James Webb Space Telescope" (JWST), which is a larger telescope than Hubble with a planned launch no earlier than 2012. The JWST will be a great telescope, but it does not replace Hubble. To save money, the JWST is being built for a narrower purpose than Hubble -- to look at red light and near-infrared light (heat). This makes the JWST perfect for researching the furthest galaxies in the Universe, because the expansion of the Universe shifts their light into the red and near infrared. But Hubble is also very capable of taking data in the blue and ultraviolet light, which is important for studying nearby stars and galaxies. When Hubble dies, no space telescope in orbit, being built, or even planned, will be able to study. Even more, ultraviolet light is blocked by the atmosphere, so telescopes on Earth won't be able to study this light either. Hubble has unique capabilities that its "replacement" won't have.
  3. Ground-based telescopes can now see just as sharp as Hubble. This is true in the infrared light, because ground-based telescopes now have "adaptive optics," which allow them to correct the blurring caused by Earth's atmosphere. But these systems don't yet work in visible light, so Hubble still beats Earth-based telescopes for clarity of vision!
  4. Robots can do the job cheaper and without risk to humans. I wish this were true! But to date, no robot has been tested successfully in space. In fact, a NASA experiment to show that a robotic spacecraft can successfully meet up with another satellite, DART, experienced several problems that have yet to be understood. The chances that a robot could be ready in the two years or so Hubble has left to be serviced before it would die from being left alone are very small, and the costs are not well constrained at this point.
So next time I'll explain why I think it is worthwhile to try and service the Hubble with a space shuttle mission.

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