On July 18, 2003, the first stage of Spitzer's Delta II rocket waits to be lifted up into the mobile service tower.

On July 18, 2003, the first stage of Spitzer's Delta II rocket is moved into the mobile service tower.

On July 18, 2003, the first stage of Spitzer's Delta II rocket waits to be lifted up into the mobile service tower.

This figure shows an artist's rendition comparing brown dwarfs to stars and planets. All objects are plotted to the same scale. On the far left is the limb of the Sun. To its right is shown a very low mass star (a so-called "late-M dwarf"), a couple of brown dwarfs (a hotter "L dwarf" and a cooler "T dwarf"), and the planet Jupiter. These objects have masses ranging from 1050 times that of Jupiter (for the Sun) through 75, 65, 30, and 1 Jupiter mass for the late-M dwarf, L dwarf, T dwarf, and Jupiter, respectively. The colors of the brown dwarfs are chosen to match an age of 1 billion years. Despite the range in mass, all four of the low-mass objects are approximately the same size, ten times smaller than the diameter of the Sun. The visible-light sequence shows how these objects might appear to the human eye: the M and L dwarfs are red, while the T dwarf is dimly magenta, due to lack of light -- actually absorptions by sodium and potassium atoms -- in the green portion of the spectrum.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope after returning to the clean room in Cape Canaveral Florida on May 2, 2003. The first attempt to launch Spitzer was delayed due to the need for additional inspections of the rocket, which necessitated moving Spitzer off the rocket that had been scheduled to launch it to make way for a Mars mission, which had a more constrained launch window.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was enclosed in a protective canister, transferred to the top of a Delta II rocket, but not launched due to engineering concerns that delayed the launch. The rocket initially meant to launch Spitzer was then used for a Mars mission, which had a more restricted launch window, and the Spitzer launch was delayed until August 25, 2003.

The Spitzer Space Telescope was placed in a faring on top of a Delta II rocket before not being launched due to the need to do additional engineering verification on the rocket. Spitzer was later moved back off its rocket and subsequently launched on a different vehicle on August 25, 2003.