An order of magnitude is the magnitude, or scale, of a class of numbers such that the numbers in that class have a fixed ratio to the class preceding it.
In the most common usage of the term "order of magnitude," the fixed ratio is 10 and the scale is the base-10 exponent that is applied to 10. Therefore, to be an order of magnitude greater means to be 10 times as large.
The Tube Challenge is the accepted name for the Guinness World Record attempt to visit all the stations on the London Underground network in the fastest time possible. Participants do not have to travel along all lines to complete the challenge, merely to pass through all the stations on the system. Participants may connect between stations on foot, or by using other forms of public transport.
The record for fastest completion is currently held by Geoff "Fat Controller" Marshall and Anthony Smith of the United Kingdom, who completed the challenge in 16 hours, 20 minutes and 27 seconds on 16 August 2013.
The Extended Duration Orbiter (EDO) program was a project by NASA to prepare for long-term (months) microgravity research aboard Space Station Freedom, which later evolved into the International Space Station. Scientists and NASA needed practical experience in managing progressively longer times for their experiments. The original space shuttle configuration usually provided a week to ten days of spaceflight. Several research projects and hardware components were part of the project, of which the EDO-pallet was one of the most visible, contracted by Rockwell International.
The first orbiter outfitted with the EDO hardware configuration was Endeavour, during its construction, and its last EDO flight was STS-67, in 1995. Endeavour's EDO modifications were removed in 1996 as part of routine maintenance, to reduce the orbiter's weight prior to STS-89. Columbia was outfitted for EDO flight during its maintenance period from August 10, 1991, through February 9, 1992, prior to STS-50, which was the first EDO flight. From 1992, through 1994, Atlantis went through a maintenance period, during which Atlantis was modified to have the provisions needed for EDO capability, but NASA chose not to proceed with the final modifications, and Atlantis does not have EDO capability. The EDO-pallet used in these orbiter configurations was destroyed in the accidentColumbia.