Tag Archives: space

An astonishing photograph

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At the recent Institute of Physics Teachers’ Group AGM, Anu Ohja from the National Space Centre in Leicester drew our attention to this incredible photograph of the Apollo Lunar Module returning to dock with the Command/Service Module.

The amazing thing about this photograph is that it contains all of humanity with the exception of one person.

Everybody alive, except for Michael Collins, who took the photograph, appears in this photograph: the entire population of Earth, plus Neil Armstrong and Buzz Aldrin aboard the Apollo LM.

The classified Space Shuttle missions

The Space Shuttle flew a total of 135 missions in its lifetime. Of these 135 missions, seven were classified Department of Defense missions whose purposes were never officially announced.*

  • STS-51-C (15th mission, January 1985) deployed a Magnum satellite designed to intercept communications, mainly from the Soviet Union and China.
  • STS-51-J (21st mission, October 1985) deployed two satellites that form part of the Defense Satellite Communications System that allows the military to communicate with units all across the globe.
  • STS-27 (27th mission, December 1988) deployed the first Lacrosse radar imaging reconnaissance satellite. It is alleged (on Wikipedia) that one of the uses of the Lacrosse system would have been to provide real-time targetting data to the B-2 Spirit stealth bomber.
  • STS-28 (30th mission, August 1989) deployed one of the satellites that forms part of the second generation of the Satellite Data System (SDS2) which relays data from low-orbit reconnaissance satellites.
  • STS-33 (32nd mission, November 1989) deployed another Magnum satellite.
  • STS-36 (34th mission, February 1990) deployed a MISTY photographic reconnaissance satellite and the PROWLER satellite. MISTY satellites are alleged to have both optical and radar stealth capabilities to make them difficult to track. The purpose of PROWLER is uncertain, but it is probably designed to inspect other satellites and intercept signals; it has been tracked from Earth approaching close to Russian communication satellites.
  • STS-38 (37th mission, November 1990) deployed the second of the SDS2 satellites.

There was also one partially classified mission:

  • STS-53 (52nd mission, December 1992) deployed the third SDS2 satellite along with a number of unclassified experiments.

The National Reconnaissance Office, one of the seventeen “elements” of the US Intelligence Community, actually influenced the design of the Space Shuttle, having its payload bay size increased so that it could accommodate the KH-9 HEXAGON spy satellite. In the end all of the KH-9 satellites were actually launched by third generation Titan rockets.

* Everything in this post should be heavily prefaced with “allegedly”.

Where is the best place to launch a rocket from?

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NASA has quite often had to “scrub” (cancel) launches from the Kennedy Space Center (KSC) in Florida because of inclement weather. But why build a Space Centre in Florida in the first place? It’s location makes it particularly vulnerable to hurricanes and other weather “events” so there must be a significant advantage to its location.

The paths of the eighty-three Florida hurricanes that occurred between 1975 and 1999.

Florida is a good location for rocket launches because it is both on the east coast of the US and because it is close to the equator.

Launching from the east coast of the US means that the rocket can take advantage of the Earth’s west-to-east spin. If a rocket were launched from the west coast it would either have to fly right across the continental US, which would be dangerous if it malfunctioned; or it would have to take off east-to-west, flying against the spin of the Earth.

At the North or South pole the speed at which you are moving, relative to a stationary observer not on Earth, is zero. As you move closer to the equator this speed increases, until at the equator you are travelling at a speed of 465 metres per second (1040 mph). At KSC, which is at a latitude of 28°N, this speed boost is reduced slightly, to about 410 m/s (916 mph). This is the best possible location in the continental USA, presumably more suitable (i.e. more southern) locations in Hawaii, Puerto Rico or one of the US’s other territories were discounted because of their remoteness.

The closer to the equator you can get, the greater the speed boost you receive. This reduces the amount of energy required to get into space and means that less fuel is required. The European Space Agency makes its launches from the Guiana Space Centre in French Guiana which is only 5° north of the equator. The commercial space launch service Sea Launch uses a mobile launch platform that sails nearly 5000 kilometres from Long Beach in Los Angeles where the rockets are assembled, to a location actually on the equator where the launches take place.

Transporting the Shuttle

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The Space Shuttle always launched from one of the two launch pads at the Kennedy Space Center’s Launch Complex 39.

But until the tenth mission (STS-41-B) the Shuttle always landed at Edwards Air Force Base in California, more than 3500 kilometres away on the opposite coast of the US.

So how did the Shuttle get back from Edwards to Kennedy? It cannot fly like an aeroplane because it has no conventional engines, only rocket engines powered by fuel contained in the giant orange external tank and two reusable solid rocket boosters. Whenever the Shuttle came into land it was not in powered flight like an aeroplane, but rather gliding, without any engine power at all – it relied on a large drag chute to come to a halt after touching down.

In order to get from Edwards to Kennedy the Space Shuttle was attached to a modified 747 known as the Shuttle Carrier Aircraft (SCA) and flown right across the US.

The Shuttle Atlantis mounted to the SCA. Note the aerodynamic cover placed over the main engines.

During the testing phase the Shuttle prototype Enterprise was deliberately released from one of the SCAs in mid-air and glided to a landing at NASA’s Dryden Flight Research Center.

The Shuttle Enterprise glides over the California desert after being released from the SCA.

A rectangular galaxy

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Most galaxies are either spiral or elliptical (“lenticular” galaxies fall somewhere inbetween).

A typical spiral galaxy, the Pinwheel Galaxy (M101, NGC 5457).

A dwarf elliptical galaxy, M110 (NGC 205).

A new arXiv preprint describes the discovery of LEDA 074886, which has a unique rectangular shape.

LEDA 074886 is thought to have formed as a result of a collision between two disc-shaped elliptical galxies that met “face-on”. The galaxy, 21 megaparsecs (68 million lightyears) away from Earth, is described by the authors of the paper as being “Emerald Cut”, which I think it pretty accurate.

Source: Alister W. Graham et al, “LEDA 074886: A remarkable rectangular-looking galaxy”, arXiv:1203.3608v1.