A Visit to the W.M. Keck HQ Visitor
Centre
Aside perhaps from the distinctive
Gemini North dome, the twin Keck observatories are the most prominent facility
on Mauna Kea summit. They are definitely the most famous, housing two 10m
telescopes that pioneered segmented mirrors and have done much of the Big
Science research in astronomy over the last few decades.
The two Keck domes sit on top of a
long low building that continues underground with workshops and all manner of
facilities. But if you go up Mauna Kea hoping for a tour you will be disappointed.
Not only can’t you visit, but most of the astronomers who use Keck don’t
either. That’s because, of course, most of the instruments and the scopes
themselves are operated remotely.
A couple of universities in Hawaii
and California have remote links to the Keck telescopes, but much of the operation
and management of Keck is done from their HQ in the small town of Waimea, which
lies to the north of Mauna Kea. The HQ complex has a visitor centre with some
very interesting displays and exhibits; it’s free and staffed by an astronomer
most days. It’s an interesting side-trip if you’re holidaying on Big Island and
especially for some extra context if you’ve already been to the summit and seen
the domes open at sunset.
Here I’ll take a brief look at how to get there
and what to see.
Getting There
The little town of Waimea lies in a
lush area of forest and arable land to the north of the mountain on a road
connecting the east and west coasts of Big Island. It’s a fairly easy and
scenic drive from Kona-Kailua to the west. The main belt road, Highway 19 north,
takes you past the airport and then into barren open land running close to the
ocean before taking a right turn inland to Waimea. The trip should take less
than an hour. Coming from the main resort on the east coast, Hilo, will take a
bit longer via Highway 19 and the scenic old town of Honokaa in the opposite
direction.
Whichever way you arrive, it’s an
easy journey and the Keck HQ is impossible to miss – it’s a sprawling complex of
low-rise cream-coloured buildings set in spacious grounds right in the centre
of town on the north side of Highway 19, just east of the main shopping mall
and Walmart.
You turn in left along the main drive,
park anywhere for free (plenty of space when I went) and follow the signs
around to the visitor centre in the middle of the buildings. There you’ll find
the main entrance below a big window patterned after the segmented Keck mirrors.
The visitor centre – small, but packed with exhibits – is in the main foyer.
What to See
During core hours you’re likely to be
greeted by a member of staff who will offer you a free tour of the exhibits –
this is well worth accepting, as the guy who showed me around was a
professional astronomer with extensive and interesting knowledge of the scopes
and their operations.
The most interesting exhibits include:
·
Detailed
cutaway models of the observatory, domes and telescopes
·
Part
of an actual Keck mirror segment made of Zerodur, a special low expansion glass also used in high-end
amateur telescopes. I was astonished how thin the Keck mirrors are
·
An
early instrument, the Near Infra-Red Camera, that was used from the early days
of Keck (c. 1993). This large and sophisticated instrument package, used for
capturing IR spectra, was the most capable IR camera in the world at that time
·
Lots
of information boards on the telescopes, their design and plans for future
instruments and research, along with various images taken with the Keck 10m
telescopes
By far the most interesting thing,
though, were the anecdotes from the guide, Edward.
Information from the Tour
There follow some highlights of the
very informative tour, if you’re interested to learn more about the design of this
giant observatory and how it operates.
The twin domes themselves are about
100ft high and 120ft across. They have walkways and gantries for inspection and
frequent ice removal. The workshops lie in the long low building between the
domes and are partially buried underground for protection from the harsh winter
conditions at 4000m. And those conditions can be harsh indeed, Ed’ told us, with
high winds, snow and ice a frequent problem. You might imagine the weather as agreeable
all year round on Hawaii, but they did almost no work at all during February
2019 due to wind and ice.
The two telescopes were originally intended
to work as an interferometer, but this proved hard to do at optical wavelengths
and required a team from California. Nowadays, the adaptive optics provide
excellent resolution anyway and allowing the two scopes to host different
instruments (four on one, six on the other) bookable by different teams expands
the work the observatory can do.
On most nights there is just a
skeleton crew of two left up at the observatory to fix any problems that may
arise during an observing session. The workshop facilities are apparently
extensive and quite self-sufficient, including the ability to re-coat the
mirror segments without transporting them off the mountain.
Although there are only 72 segments
(36 per scope) in use, they actually have about 80 to allow round-robin
re-coating of segments without interruption to observing. They have to handle
those thin Zerodur mirror segments with extreme care
as they were cast and ground thirty years ago and the equipment used no longer
exists so new ones would be hard to make.
Interestingly, segmented mirrors were
a completely new idea, pioneered by Keck. Each mirror is minutely controlled by
actuator and computer. The number 36 represented the limit of computing power
in the early nineties, but the new 30m telescope will have as many as 500 segments.
Another use of actuated mirrors and
computers is the adaptive optics system fitted to each telescope. A powerful
sodium laser creates an artificial star by exciting sodium ions high in the
mesosphere. The measured scintillation is then cancelled in real time by a
piece of optics in the beam path. To avoid interfering with aircraft, the
summit is a no fly zone and liaison with NASA is required
to avoid zapping passing satellites! In addition, all the observatories on Mauna
Kea liaise in order to avoid laser conflicts, filling in a central log of where
they’ll be pointing their beams.
One of the visitors on my tour asked
why Keck doesn’t produce a calendar. The answer was unexpected. Apparently,
Keck mostly studies distant object using wavelengths not conducive to ‘pretty
pictures’ (as Ed’ put it). However, the nearby CHFT telescope studies closer
objects and does produce a calendar every year.
The Keck HQ is well worth a visit if
you’re on Big Island (plan on an hour or two). I found both the displays and
talk a rich source of answers to all the questions I had after my summit tour.
Keck domes with Subaru behind.