TV from the Moon

The Apollo 11 Lunar Module, “Eagle”, touched down on the Sea of Tranquility on the morning of Monday 21st July 1969, Australian time.

Madrid and Goldstone were tracking during the Powered Descent and landing – which took place at 6:18am Eastern Australian time.

The EVA (Extra-Vehicular Activity) had been scheduled for after an astronaut sleep period. The Moon would have been high in the sky for Honeysuckle Creek and Parkes, but below the horizon for Goldstone. Armstrong and Aldrin’s understandable decision to walk early changed that. It meant that Goldstone could still see the Moon and would be able to receive the TV.

At Honeysuckle Creek, the Moon had risen next to Dead Man’s Hill, the high hill due east of the station at 11:12am.

Both Goldstone and Honeysuckle relayed voice and telemetry from Tranquility Base as the astronauts prepared for their EVA.

The larger Parkes Radio Telescope – not designed for spacecraft tracking – could not tilt as low to the horizon as Honeysuckle’s dish. Parkes could not see anything lower than 29°38' above the true horizon. Therefore the Moon did not rise into its main beam until 1:02pm Eastern Australian time – almost two hours after it rose for Honeysuckle. However, by using another receiver in a less sensitive off-axis position, the Parkes dish was able to receive data and television several minutes before that time.

The television camera taken to the lunar surface was a Westinghouse designed and built slow-scan black and white camera with a vertical resolution of 320 lines scanned at 10 frames per second. This camera was chosen because the available bandwidth from the Moon (500kHz) was not sufficient for a standard TV signal.

On Earth, the received slow scan signal was converted to a standard TV picture (in this case, the American standard of 525 lines and 30 frames per second) using specially built scan converters. At Goldstone and Honeysuckle, the conversion was done on site. The Parkes slow scan TV signal was sent to the OTC (Overseas Telecommunications Commission) Paddington gateway exchange in Oxford Street, Paddington, in Sydney and converted there.

At Paddington (‘Sydney Video’) the best of the two signals from Honeysuckle or Parkes was chosen and sent to Houston via Intelsat through the OTC Moree ground station. Charlie Goodman, seasoned communications expert from NASA was responsible for selecting which signal was sent.

While the TV from Parkes went direct to Sydney, all the rest of Parkes data was sent (via Sydney) to Honeysuckle Creek, which demodulated Parkes data and combined it with its own for transmission to Houston.

As Neil Armstrong made his way down the ladder of the Lunar Module, he deployed the TV camera, which swung out from the MESA on the side of the descent stage. Goldstone and Honeysuckle were monitoring the FM portion of the signal from the Lunar Module, waiting for a TV signal.

Buzz Aldrin put the TV circuit-breaker in, and both Goldstone and Honeysuckle simultaneously reported they were receiving video.

Viewers around the world saw fuzzy images – upside-down for a few seconds – coming from Goldstone. The image was high contrast because the scan converter at Goldstone had apparently been set incorrectly. This compressed most of the video information into the black, making it almost impossible to discern what was happening.

Just before Neil Armstrong set foot on the moon, Houston selected the clearer video coming from Honeysuckle Creek.

In 2003, John Saxon scanned a set of photographs taken by Ed von Renouard of the TV monitors on the video console at Honeysuckle Creek as the pictures came in from the Moon.

See them here.

See also a scan of a Polaroid taken at Goldstone – provided by Bill Wood.

The high resolution slow-scan TV monitor is this one at the top of the slow-scan TV processing rack to the left of Ed von Renouard at the TV operational console at Honeysuckle.

This monitor could display the ‘standard’ slow scan picture of 10 frames per second at 320 lines per frame or a high resolution mode of 0.625 frames per second at 1280 lines per frame.

In practice, only the lower resolution video of 320 lines was a part of mission plans and was transmitted back to Earth.

Directly above Ed’s head (and clearly visible in the large version of the photo) is the toggle switch to invert to television for the beginning of the broadcast when the camera was mounted upside-down in the MESA on the side of the descent stage of the Lunar Module.

This photo was taken during the Apollo 12 mission. Scan by Hamish Lindsay. Large, Larger.

This diagram by Hamish Lindsay, after a 1969 PMG sketch, gives an idea of the communications links within Australia used to support Apollo 11.

Note while that Carnarvon tracking station did not have scan-conversion capabilities – nevertheless, after the Moon rose, staff at the station were able to extract the slow scan TV and view it within the station (details coming soon).

The nearby OTC Carnarvon earth station nearby received the television from the Intelsat III Pacific telecommunications satellite. It was this which was relayed to Perth via coaxial cable.

The Parkes supplement to the (Goddard) NOD (Network Operations Directive) Section 36 – dated June 1969.

This document details the timeline for the equipment setup at Parkes, its integration with Honeysuckle, and the paths for the various signals from Parkes and Honeysuckle.

Click for the 1.3MB PDF. With thanks to the Apollo 11 Tape Search Team, Sept 2006.

This diagram – from the Parkes supplement to the (Goddard) NOD (see above) summarises the links between Honeysuckle and Parkes and Sydney.

From Parkes:

The received telemetry (including the Slow Scan TV) was sent via the temporary microwave link to the Mt. Coonambro repeater, and then to Orange, and the rest of the way to Sydney via the PMG broadband microwave link.

The signals then travelled via the Redfern and City South telephone exchanges, and then into the Overseas Telecommunication Commission’s gateway exchange in Oxford Street, Paddington.

At Sydney, the Parkes Slow Scan TV was scan converted to 525 lines / 60 fields.

From Honeysuckle Creek:

Since Honeysuckle had a scan converter on site, what was sent to Sydney was telemetry and 525 line / 60 fields TV.

The TV signal left the microwave tower at Honeysuckle, through a specially installed microwave dish, to an AWA outside broadcast van parked next to the Cooma – Canberra microwave tower on a hill east of the locality of Williamsdale. Because the Honeysuckle tower did not have line-of-sight to Williamsdale, a temporary relay tower was built about a kilometre down the road from Honeysuckle.

From Williamsdale, the link went to Red Hill in Canberra, and then into the broadband network to Sydney. At Red Hill, the signal was split – so the TV went to Sydney via both the microwave broadband network and also via the coaxial cable.

From Paddington in Sydney there were three feeds going out:

a.) The telemetry and voice from Parkes (including critical information on LM and PLSS systems) was sent down the link to Honeysuckle, where it was demodulated and the best data (from Honeysuckle, from its wing at Tidbinbilla or from Parkes) was used.

b.) The scan-converted TV (selected from either Honeysuckle or Parkes) was sent back through City South and Redfern exchanges and via microwave bearers, up to Moree in northern New South Wales.

From the Moree telephone exchange, the TV went to the nearby OTC Satellite Earth Station, and then by the Pacific Intelsat III F4 satellite to the US west coast Earth Station at Jamesburg in California – and then via AT&T links to Houston. From Houston, the TV was released to the world in real time.

(Contrary to some common misunderstandings, there was no added delay in either the video or audio – everything was live.)

c.) The only place in the world where the public saw the lunar TV direct, and not via Houston, was in Australia. This was because, some months earlier, GSFN engineers sought approval to release a live feed of the TV from Sydney Video, to the Australian television networks.*

Thus, as the TV was sent from Sydney Video to the Moree Earth Station, a spilt was sent, via the Post Master General’s Television Operations Centre in Castlereagh Street, Sydney, to the Australian Broadcasting Commission’s studios at Gore Hill in Sydney’s northern suburbs.

At Gore Hill, engineers used a locally-built optical scan converter (reportedly mounted on a wooden packing case) to produce a 625 line / 50 fields per second version of the broadcast. The ABC also provided their 625 line feed to the Australian commercial networks, although the Sydney commercial stations TCN-9 and ATN-7 also used their own scan converters.

It was this “Sydney Video” version of the broadcast which was seen by viewers across Australia (including Perth, who received the signal from Moree via the Carnarvon OTC Earth Station).

* Those stories to come soon.

The Apollo TV was sent from Sydney Video via PMG lines to the OTC’s satellite earth station at Moree in northern New South Wales.

From there it was sent to the Intelsat III F4 geosynchronous telecommunications satellite above the Pacific Ocean.

This photo of the OTC’s 90 foot Moree dish was taken from the cover of a 1969 OTC publication. Scan: Colin Mackellar.

Large, Larger.

Artist’s impression of the Intelsat III Pacific Ocean satellite. In 1969, NASA was the prime user of the satellite.

From a 1969 OTC publication. Scan: Colin Mackellar.

NASCOM – The NASA Communications network for Apollo 11. From a Goddard diagram, with colour added by Hamish Lindsay.

Note: This diagram applies to voice / data. Apollo 11 EVA television from Sydney Video went to the OTC Moree Earth Station, via Intelsat III to an Earth Station at Jamesburg in California, and then via landline direct to Houston (while the voice and data went to Houston via Goddard).