One century after the Wright brothers proved it was possible to build a piloted heavier‐than‐air “flying machine,” several airlines will soon, perhaps as early as October 2005, begin to operate the largest passenger aircraft ever built, the Airbus A380. The A380 is nearly half again as large, in terms of passenger floor space, as the Boeing 747‐400. It can be configured to hold as many as 840 passengers, and it has a takeoff weight of 550,000 kg, a maximum range of 15,000 km, and a cruising speed of Mach 0.85.The remarkable advances in aeronautics realized during the past century make it difficult to understand how anyone, let alone Simon Newcomb, one of the most prominent U.S. scientists at the turn of the twentieth century, could have opposed efforts by Samuel Pierpont Langley to build a piloted winged aircraft for the military. Newcomb argued that Langley was doomed to failure because the technology required to build such an aircraft was not then available, and he bemoaned the “waste” of scarce government funds toward the effort.

AbstractThe U.S. Naval Observatory Navnet program monitors changes in the rotation of the Earth on a regular basis using radio interferometric observations acquired with telescopes in Alaska, Hawaii, Florida, West Virginia and, in the past, Maryland; other radio telescopes have also participated occasionally. These observations have been used to derive a radio interferometric celestial reference system, Navy 1990-5, using two years of dual frequency measurements from 24-hour-duration observing sessions. A total of 84 extragalactic radio sources, mostly quasars, have been observed by the Navnet program to date, of which 70 currently have source position formal errors of one milli second of arc or less. The root mean square of the difference between source position estimates from the Navnet data and an independently derived catalog using completely different data is less than one milli second of arc in both right ascension and declination after the adjustment of an arbitrary rotational offset between the two celestial reference frames.

A cooperative program has been established to produce a reference frame of at least 400 suitable extragalactic sources. This is an extension of collaborative efforts (Johnston et al. , Russell et al. , Ma et al. , and Reynolds et al. ) reported at this meeting. In Phase One, a catalog of radio source positions will be constructed using original VLBI observations already obtained by NASA, NGS, NRL, JPL and USNO. Observations will be re-reduced in a consistent system to avoid some of the more serious problems associated with the formation of compilation catalogs. In Phase Two, the USNO will maintain the system, including the monitoring of source structure and/or variation. During both phases cooperation among the various agencies will continue. A list of sources will be made available to optical observers so that the frame will have benchmarks in both the optical and radio regimes.