Monthly Archive for September, 2011

Mapping Everything

Published by The National Air and Space Museum on September 30, 2011 in Astronomy and space.
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The universe is about 13.7 billion years old and has expanded since its beginning at the Big Bang. Because distant objects appear to be receding as the universe expands, the light from them is “stretched” out, altering its wavelength to the red part of the electromagnetic spectrum.

This “redshift” can be measured for every object in deep space. The more distant the object, the greater its redshift. The relationship between distance and redshift was first described by Edwin Hubble in 1929 and remains fundamental to our understanding of the expanding universe.

Light from distant objects has been traveling towards the Earth for billions of years. In other words, we see distant objects as they appeared when the light left them. It is therefore possible to use telescopes to peer into the past. As astronomers have observed to ever more distant objects, it became possible to see into the very early stages of the universe. At the very edge of the observable universe, it is possible to detect electromagnetic radiation in all direction.

This cosmic microwave background radiation is the leftover energy from the Big Bang and the origins of our universe. This background radiation is literally the “echo” of the Big Bang.

WMAP

Cosmic background radiation as measured by the Wilkinson Microwave Anisotropy Probe (WMAP).

This illustration shows the cosmic background radiation as measured by the Wilkinson Microwave Anisotropy Probe (WMAP). This spacecraft was launched in 2001 into a halo orbit around the L2 libration point beyond Earth’s orbit. The cosmic background radiation was emitted about 13.7 billion years ago in the aftermath of the Big Bang, and has been stretched to the microwave part of the electromagnetic spectrum by the expansion of the universe. The colors indicate the intensity of the background radiation, which can be measured as temperatures barely above absolute zero. Reds signify temperatures about 0.0002 degrees Kelvin higher than blue areas. These differences reflect the “clumping” of matter that would later occur in the early history of the universe. This 360-degree view of the night sky has been mapped to a flat surface in the same way a global map of Earth is projected to a sheet of paper.

local galaxies

Local Group of Galaxies

The chart above shows the Local Group of galaxies. This gathering of galaxies is bound together by their mutual gravitational attraction. The largest two galaxies in the Local Group are the Milky Way and Andromeda. These two galaxies are approaching each other. About three billion years in the future they may merge to form a new, larger galaxy. Each galaxy is shown here about three times its actual size.

Sloan Diagram

Sloan Digital Sky Survey at 2 Billion Years

 

This chart above shows data from the Sloan Digital Sky Survey indicating the distribution of galaxies in the universe. The Local Group is at the center of this diagram, but it is too small to be visible at this scale. Dots show the density of galaxies, each consisting of hundreds of billions of stars. The positions were determined by measuring the redshift of each galaxy and their angular position.

sloan diagram

Sloan Digital Sky Survey at 10 Billion Years

As we peer into greater distances, we are in effect seeing back in time. Telescopes do not show deep space objects as they are – they show objects as they were billions of years ago. Because of this, representations that attempt to show the entire universe need to incorporate time as well as space. As we look out in space, and back in time, vast distances can be referred to as a “lookback time.” This chart shows data from the Sloan Digital Sky Survey. Close to the center, small dots show the density of galaxies. Beyond a lookback time of about 5 billion years, most of the dots represent quasars instead of galaxies. Quasars, or “quasi-stellar” objects, are likely the cores of energetic galaxies. The objects were much more plentiful in the early universe and emitted enormous amounts of radiation. Due to their distance only their energetic emissions are visible. At the very edge of what is visible, we can detect the cosmic microwave background.

Roger Launius is a senior curator in the Space History Division of the National Air and Space Museum.

 

Telstar and the “Global Village”

Published by The National Air and Space Museum on September 27, 2011 in Hidden Treasures, History, space and Stories.
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Since October 1997, the Space History Division has been celebrating a number of fiftieth anniversaries: Sputnik, Vanguard, Yuri Gagarin’s flight, Alan Shepard’s Mercury Flight. Next July we hope to celebrate another. On July 10th, 1962 at 11:47 GMT, the world’s first transmission of a television image by satellite took place, using the Telstar satellite. Prior to Telstar’s launch that summer, NASA experimented with a passive reflector—“Echo” to transmit signals over the horizon, but engineers soon realized that the most practical way to transmit television, with its high bandwidth requirements, was by an “active satellite”: one that would receive a signal and then retransmit it to a ground station on another continent.  (Most people know the name “Telstar,” if not for the satellite, then for the hit instrumental song by the Tornados, with its “space age” synthesizer sound.)

 

Telstar

An engineering back-up of the Telstar satellite, in the collections of the National Air and Space Museum.

dome

The antenna was located in a remote area of Brittany, the westernmost part of France. It was protected by a flexible Mylar dome, which was transparent to microwave radio frequencies. Photo: Musée des Télécoms, Pleumeur-Bodou, France.

Last week I had the great fortune to visit the French village of Pleumeur-Bodou, on the Brittany coast, where that first transmission was received. The microwave antenna in the US, at Andover, Maine, was dismantled years ago, but the one in Brittany has been preserved and is in excellent condition (although it is no longer used). Because Telstar flew in a low-Earth orbit, it was only visible to the ground stations for a few minutes at a time, unlike today’s geostationary satellites, whose 24-hour orbits position them in the same place in the sky at all times. So the antenna had to track the satellite carefully as it passed overhead. Unlike modern dish-shaped antennas, this one was shaped like a giant horn, based on the design of microwave repeaters built by AT&T for long-distance telephone in the U.S.  Entering the 64-meter (210 foot) diameter protective Mylar dome, and climbing onto the giant horn was an experience I will never forget.

Telstar Antenna

The antenna was not a dish but a horn, mounted on bearings to track the satellite as it passed overhead. The design was adopted by AT&T, which built it, based on existing microwave telephone relay antennas. Photo: Musée des Télécoms, Pleumeur-Bodou, France

It worked. The initial test on July 10 was followed by images of the U.S. flag waving, Mt. Rushmore, and a “live” portion of a press conference held by President Kennedy. The French, in turn, transmitted a tape of Yves Montand singing “La Chansonnette.” After a string of Soviet firsts in space, this was one the U.S. could claim as a first, finally. A modest beginning, but look at what Telstar has brought us. We take it for granted that whenever there is a major event happening anywhere in the world: a Royal wedding, a benefit rock concert, an earthquake—anything—we expect to see it “live.” Marshall McLuhan prophesized that the “cool” medium of television would make us all inhabitants of a “global village.” That did not happen right away, which led people to dismiss his predictions as mere fancy. But with the combination of satellite telecommunications, the Internet, and Facebook (the last two appearing after McLuhan’s death), who would say that he was wrong? And it all began with Telstar.

Paul Ceruzzi is Chair of the Space History Division of the National Air and Space Museum.

Preserving and Displaying the “Bat-Wing Ship” – August Update

Published by The National Air and Space Museum on September 9, 2011 in Aviation, Behind The Scenes, Hidden Treasures and restoration.
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This post is a follow up to Preserving and Displaying the “Bat-Wing Ship” published on June 24, 2011.

The Smithsonian Museum Conservation Institute (MCI) Conservators and National Air and Space Museum staff spent July and August continuing to investigate the Horten H IX V3 jet fighter for preservation and preparation for display.  Senior Conservator Melvin Wachowiak took the following detailed photographs on Tuesday, June 21, 2011.

Conservators are attempting to determine if the degradation of the plywood is caused by a failure of the adhesive or by biological deterioration of the wood.  Understanding the cause of the deterioration will guide their immediate and long-term preservation strategies.  One of the greatest challenges in this treatment will be in determining the most appropriate adhesive and finding effective methods of getting the adhesive to penetrate into deep areas of delamination. Photos 1 and 2 (seen below)—show 11 sheets of 5 cross-laminated plies each.

 

Horten

Photo 1. Artisans have built airplanes with plywood since well before World War I because crossing each layer, or ply, counters the weakness of a single sheet when bent with the grain rather than across the grain (Melvin Wachowiak /Smithsonian MCI photo).

 

 

Horten

Photo 2. (Melvin Wachowiak /Smithsonian MCI photo).

 

Horten Wing

A robust network of welded steel tubing frames the right outer edge of the H IX V3 center section. Behind the tubing lies a maze of plumbing for one of the Jumo 004 jet engines, the fuel system, and other equipment (Melvin Wachowiak /Smithsonian MCI photo).

 

Horten

German artisans formed the wood around the nose of the H IX center section using steam to make it soft and pliable, and then bending it to shape. Said Melvin Wachowiak , Senior Conservator, Smithsonian Museum Conservation Institute, "I am still impressed by the bending of the laminated plywood into a conical section without cracks. Nearly 70 years on! The degradation of the broken plys is more like a form of brown rot, but we will have to see what turns up (after further analysis)." (Melvin Wachowiak /Smithsonian MCI photo).

 

Horten

This photograph by Kenneth S. Kik shows the outer wing panels attached to the center section of the H IX V3 now in treatment at the Paul E. Garber Facility. (Photo credit: Mr. Kenneth S. Kik, 1950. Copyright unknown)

 

Russ Lee is a curator in the Aeronautics Division of the National Air and Space Museum, and Melvin Wachowiak is a Senior Conservator at the National Air and Space Museum.