Located in the Southern Suburbs of Cape Town and founded in 1820, The South African Astronomical Observatory (SAAO) is the national centre for optical and infrared astronomy in South Africa. Its primary purpose is to conduct essential research in astronomy and astrophysics. It does so by providing a world-class facility to scientists both locally and from abroad. Further to this, the SAAO promotes astronomy and astrophysics in Southern Africa to local and international audiences and research bodies by sharing research findings and discoveries.

Originally this historic observatory was established to keep shipwrecks from littering the Cape of Good Hope. The 200th anniversary of the establishment of the Royal Observatory at the Cape of Good Hope was celebrated in 2020 and until work began in 1820, the treacherous seas around the Cape of Good Hope saw more than 500 years of ships battering and crashing through the South Atlantic, with little to no usable stellar navigation established. Without the positions of the southern stars accurately mapped, ships were often on their own, in unfamiliar waters and under unfamiliar skies. You can follow this link https://www.saao.ac.za/about/history/ for more on the history of this world-renowned institution.

Fast forward 200 years and while the heart of the operation still remains true to its original establishment – a focus on astronomy – a much bigger function overall now exists, especially for the SAAO’s own inhouse fully equipped machining facility that focuses on delivering components with scientific precision.

Craig Sass, Mechanical Workshop Manager at SAAO, and the recently installed (April 2024) Kitamura Mycenter-HX400iG horizontal machining center complete with Renishaw probing was supplied and installed by WD Hearn Machine Tools and offers SAAO true, heavy-duty, medium to large part machining capabilities. This machine will do all of SAAO’s milling work, relieving their other machines so that they can be used to concentrate on custom work for SAAO. This is SAAO’s second Kitamura

“The manufacture of astronomical instrumentation is the core part of our work and what we do here – difficult machining is what we do. We are an application specific mechanical workshop,” explains Craig Sass, Mechanical Workshop Manager at SAAO.

“At the moment we are running some night shifts just to be able to keep up with the work. Mostly this is anything that the National Research Foundation (NRF) needs. They have some small research labs but they are limited in what they can do.”

“We are still machining lead radiation shields for iThemba LABS and these are machined out of lead. We will machine about 20 of these a month and these are then exported. They are busy setting up a new cyclotron and the aim for production is to go five times the original amount of batch production, which was 10 a month.”

“This was why we installed the Hwacheon Hi-TECH 350BL horizontal turning center a few years ago – this machine does all the turning and the new Kitamura will do all the milling, relieving our other machines so that we can use them to concentrate on our custom work for SAAO. This is the harder stuff to do. You must remember that a lot of these components are all one-offs. But when doing production parts, once you’ve got the production process up and running, the rest is easy. Whether you are running production or custom parts, the design, research and development takes a lot of time.”

SAAO’s Hwacheon Hi-TECH 350BL horizontal turning center that was supplied by Lead Machine Tools a few years ago and is equipped with a Fanuc OiTF CNC control. The machine is ideal for tough, hard materials with high cutting volumes and precision requirements. It is ideal for machining the lead billet that weighs 33 kilograms when SAAO is machining the inner column sleeves called isotope shielding holders for iThemba LABS. SAAO will machine about three kilograms off the original billet

The recently installed (April 2024) Kitamura Mycenter-HX400iG horizontal machining center supplied and installed by WD Hearn Machine Tools offers SAAO true, heavy-duty, medium to large part machining capabilities. The machine comes complete with Renishaw probing, 15 000rpm BBT40 Dual contact spindle, Arumatik-Mi control with 2700 block look ahead, +- 0.001/0.002mm full stroke accuracy and repeatability spec, 60m/min rapids on box way slides. It has a large work envelope that houses standard 4th axis rotary tables that allow full 360° 4th axis capability simplifying machining of more complex, multi-sided parts, with a table size of 400mm x 400mm. This is SAAO’s second Kitamura, the other machine being a Kitamura Mytrunnion 4G – 5 axis machine.

“A lot of this stuff that we do has just never been done before. I’m trying to train people but to find the time is also difficult – often when these orders come in, we have to get the job done very quickly and we’ve got to get it right otherwise we could fall behind schedule. We are slowly ramping up the training and skilling of people to take away some of the EDM work from myself for example. I’ve been working with that EDM cutter for 13 years now, and even today my skills get stretched. With this training though it will also allow me to manage the overall scheduling of the machine shop much better.”

Sabyasachi Chattopadhyay, Faculty Astronomer at SAAO and who is involved with the SAAO’s fibre optic instrument building operations. The basic idea is that you take bundles of tightly packed fibre (housed within components machined by SAAO) and point it at the sky or object for observation such as a distant galaxy for example

“One of our most recent projects has been the design of an instrument selector for one of the telescopes. Prior to us designing and manufacturing this selector, the process of changing out a particular instrument for certain types of observations was a manual process and one that would take place every two weeks. It would take a whole morning just to change out an instrument. So an observer might have had to wait two weeks for an instrument change in order to carry out whatever they needed to observe. With things having begun to move in a robotic direction some time ago already, this instrument selector enabled specific instruments to be changed out very quickly and thus freed up the telescope for someone or a team to carry out observations that are time critical. We have also set up a few control rooms on site here and for example this one next to us can actually run the Southern African Large Telescope (SALT).”

The Southern African Large Telescope (SALT) is the largest telescope in the Southern Hemisphere, with a mirror measuring 11.1 by 9.8 metres. It is located at the South African Astronomical Observatory near Sutherland, at an elevation of 1 798 metres.

Fibre optic inclusive instruments
As technology has evolved, so has its uses. Another recent addition to the instrument manufacturing scope of work carried out at SAAO is that of the use of fibre optics, or light collection guide instruments. The basic idea is that you take bundles of tightly packed fibre (housed within components machined by SAAO) and point it at the sky or object for observation, such as a distant galaxy. That light is then channelled back to the instrument to produce a hyperspectral image (HSI) or integral field spectroscopy.

Hyperspectral imaging captures and processes data across a wide electromagnetic spectrum, providing detailed information about objects or scenes. It involves acquiring and analysing images at numerous narrow spectral bands, enabling enhanced discrimination and identification of materials, substances, or features based on their unique spectral signatures. Hyperspectral imagers collect measurements from a much larger number of spectral bands – up to hundreds – and hence why the components machined by SAAO that house the fibres have to be to the tightest tolerances to ensure that the on-sky footprint of fibres are well known which helps further to fill gaps between fibres with additional exposures.

SAAO have had to design and manufacture a special jig to assemble fibres into bundles that then get pushed into the aperture of the instrument to allow the fibre optic observations to take place. Light is then channelled back to the instrument at very acute angles to produce a hyperspectral image (HSI). This particular jig pictured is destined for a research team in Hong Kong

The key benefit of this type of technology is that the fibre bundles – long, and obviously very thin – mean that one does not need to have a perfectly straight line to make the observation as the cables are flexible and the light merely reflects through the cables back to the instrument to produce the required data. Further to this, the light analysing instrument (e.g. a spectrograph) can be safely tucked away from the telescope’s rugged, dusty conditions thus preserving them, and the data gathered, from external elements, for instance, within a temperature and dust-controlled environment if need be.

Of course, key limitations of such technology, along with all astronomical observation equipment, are nature’s own natural elements such as wind, dust, cloud cover, and rain and humidity. Again, this is what makes the Sutherland region one of the best observation regions in the world and Sass is adamant that the SAAO has the inhouse capabilities of further developing this technology to the point where South Africa can think about calling itself a world leader in this respect, if it isn’t already one.

On the cards are an investment in a new EDM able to spark to even tighter tolerances to allow the team to work with even smaller fibres. The goal Sass says is to reduce the current fibre housing’s 400 micron tolerances down to 50 microns. Currently there are collaborative projects where this South African technology is being used involving Hong Kong, the US and various other places around the world. The fact that these countries want to use the SAAO-developed instrument is testament to the calibre of work being carried out by the SAAO team. SAAO have also had to design and manufacture a special jig to assemble these fibres into bundles, which then get pushed into the aperture to allow the observations to take place with the instrument. This has to be very accurate due to the miniscule size and complex nature of the fibres.

Various components designed and machined by SAAO, many of which end up being one-off astronomical observation instrument-specific components. Pictured bottom centre is a prototype ventilator that was designed and manufactured by the SAAO at the beginning of the Covid pandemic

Superior mechanical engineering capabilities
Kathryn Rosie, Mechanical Engineer at SAAO, along with her team, are responsible for the design and development of new instruments that astronomers use with telescopes to obtain their data. One such critical component made up of many components is SAAO’s vacuum cryostat.

It is a crucial component of astronomical instrumentation, particularly for infrared observations. It serves to cool detectors and instruments to extremely low temperatures, typically around minus 100 – 110 degrees Celsius, to minimise thermal noise and enhance sensitivity. The cryostat is meticulously designed to create a vacuum-insulated environment, shielding the sensitive instruments from external heat sources and maintaining stable conditions for precise astronomical measurements.

This device enables pioneering research across various fields, including studying distant galaxies, star formation, and planetary systems. Its efficient cooling – either using liquid nitrogen or various other cryogenic cooler technologies, as well as specially designed heatsinks – capabilities ensure that astronomers can capture faint signals from celestial objects with unparalleled clarity, advancing our understanding of the universe’s complexities.

The SAAO conducts various outreach programmes such as their Open Nights to educate residents about physics and astronomy. The SAAO Open Nights in Cape Town take place on the second and fourth Saturday of every month at 20:00 at their premises in Observatory. All Open Nights will start with a presentation on topics of astronomy or physics. Then, visitors will be given an introduction to the historic McClean telescope, the observatory museum, and the library. If the weather is clear, there will be a chance for stargazing using telescopes set up for the night. Pictured is a control centre which remotely controls various telescopes for observations, including the Southern African Large Telescope (SALT) – the largest telescope in the Southern Hemisphere

Housed herein is the core technology of an astronomical detector – a CCD (Charge-Coupled Device) detector. It is a light-sensitive electronic device used to capture and record images of astronomical objects. It converts incoming photons into electrical signals, allowing astronomers to study the intensity and properties of light emitted by stars, galaxies, and other bodies with high precision. A critical component of the CCD is the silicon wafer that absorbs the photons before converting them to electrons. This device needs to be cold in order to work efficiently and this is why it is housed within the vacuum cryostat – as Rosie jokes, astronomers don’t like interferences in their pictures. Rosie continues that the SAAO tries to do as much of everything themselves inhouse and this is further reason as to why the machine shop has been expanding its capabilities.

Further to the SAAO’s important work and responsibilities toward astronomical observation advancements, they also conduct various outreach programmes such as their Open Nights to educate residents about physics and astronomy. The SAAO Open Nights in Cape Town take place on the second and fourth Saturday of every month at 20:00 at their premises in Observatory. All Open Nights start with a presentation on topics of astronomy or physics. Then, visitors will be given an introduction to the historic McClean telescope, the observatory museum, and the library. If the weather is clear, there will be a chance for stargazing using telescopes set up for the night.

For further details contact the South African Astronomical Observatory on TEL: 021 447 0025 or visit www.saao.ac.za