Thursday, 2 April 2015

Hartebeesthoek Radio Astronomy Observatory

I had the supreme privilege the other Saturday of having a personal tour of the Hartebeesthoek Radio Astronomy Observatory near Johannesburg.
15 03 21 Hart RAO (7)
15 03 21 Hart RAO (15)
Hart RAO was built by NASA in 1961 with a 26m dish antenna to track space probes. Over time is has become a radio astronomy observatory conducting space geodesy as well as astronomical work.

Prof Ludwig Combrink showed us around.  What a mine of information!  And what a cool bit of astro bling to have in one's office.
15 03 21 Hart RAO (6)
We started in the control room.  SLR on the left behind us, VLBI on the right (or so I recall).
15 03 21 Hart RAO (3)
He then showed us his two atomic clocks.  Accurate to something greater than my mind could cope with (loses less than a second every 300 years?).  To be honest he could be showing me his beer fridges and I'd be just as impressed ;-)
15 03 21 Hart RAO (5)
Ludwig is an incredibly smart cookie.  He wrote the algorithms for lunar laser ranging and was first to spot an anomally in a recent satellite gravity mission.  Blows your brains.
15 03 21 Hart RAO (11)
He wrote all this software.
15 03 21 Hart RAO (13)
There are only a few observatories that measure to the moon.  By the time the 75cm diameter pulse has been flung out from their lasers it has a footprint 6.5km wide on the surface of the moon.  Still then, trying to aim that beam correctly is like trying to shoot a coin from 3km distant.  And then you don't only have to hit the moon (aiming for the reflectors left by the Apollo mission) but catch the return beam.

Dinner party fact Number 1 - the moon is racing away from us at 3.8cm per annum.  That's quite fast in the solar way of things.

This is the GPS station for Hart.
15 03 21 Hart RAO (8)
I queried why it was outside the perimeter fence.  "Stops the kids fiddling with it," was Ludwig's response.  Hart RAO has educational visits and there is little that mischievous fingers can interfere with on a 26m dome, but a small GPS antenna is just fun to play with isn't it?

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