Engineering the future
by looking to the stars
For Keitumetse Molamu, helping South Africa explore deep space is the fulfilment of a childhood dream. As Head of Engineering and Technology Development at the South African Radio Astronomy Observatory (SARAO), she leads the people who turn difficult scientific questions into technology.
Her multidisciplinary team supports MeerKAT and the Square Kilometre Array (SKA), maintains the Hartebeesthoek Radio Astronomy Observatory (HartRAO) and develops technologies beyond astronomy.
At the Future Space Sub-forum of the Pujiang Innovation Forum in Shanghai in September, Molamu explained that discovery begins before scientists examine data.
“I come to astronomy through engineering. So, I tend to see what happens between the scientific question and the discovery: the receivers, timing systems, electronics, software, computing, structures and infrastructure that all have to work before a scientist can see something that has never been seen before,” she said.
“And that is why I think astronomy belongs in an innovation forum.”
Appointed to lead the division from September 2022, Molamu brought experience in telecommunications, optical technologies and power systems. She holds a Bachelor of Engineering, a Bachelor of Science in Information Technology and a Master of Business Administration in Information Technology. Her experience includes working at Airports Company South Africa, Ericsson, Clyde Bergemann Africa and the Royal Bank of Canada.
Astronomy explained
A Massachusetts Institute of Technology graduate, her thesis examined African innovation ecosystems, reflecting her belief that engineering should advance countries and communities.
“Innovation is often described as starting with an idea for a product. Astronomy often works the other way around,” she said.
“We start with a question we cannot answer. That question demands an instrument, or a capability, that may not exist yet. Building it forces us to solve difficult engineering problems. And when we solve them, we are left with capability that did not exist before.”
Inaugurated in the Karoo in 2018, MeerKAT has become an important scientific asset. Since its first full-array science paper in 2019, more than 700 scientific articles have been published. Observing demand is three to four times its capacity, with more than 1 000 proposals from 30 countries.
“But numbers are not really the interesting part,” Molamu explained.
One early result revealed enormous bipolar radio bubbles at the centre of the Milky Way. Evidence points to an energetic event there millions of years ago.
“I like this result because it says something important about science. You build an instrument to answer a question and, if you are lucky, it shows you something you did not know enough to ask about. And then the discovery creates the next problem.”
Molamu used rapidly rotating neutron stars called pulsars as an example. Their radio pulses can function like cosmic clocks, helping scientists search for gravitational waves.
“That sounds like an astronomy problem. But the words ‘precisely enough’ turn it into an engineering problem,” she added.
The MeerKAT Pulsar Timing Array uses about 80 millisecond pulsars. Its 4.5-year dataset has matched the significance of searches using much longer datasets. Engineers drove MeerKAT’s absolute timing uncertainty below seven nanoseconds.
Science versus engineering
“At that level, it is not enough to have a good clock and declare the problem solved. Every element in the signal chain introduces delay. Those delays have to be measured component by component, understood, calibrated and integrated,” she explained.
“A scientist asks a question about gravitational waves. The question creates a requirement for extraordinary timing precision. That requirement creates engineering problems. Solving those problems creates technology, know-how and people capable of working at that level of precision,” she added.
“Science creates the problem. Engineering creates the solution. Solving the problem creates capability. So, whether we are measuring a radio pulse to nanosecond precision or positioning an optical component to micrometre precision, the point is the same: astronomy gives us a difficult problem to solve,” she said.
Building capabilities
As a result, she resists measuring a scientific facility only by its published papers. The country should also ask what capabilities it acquired through producing the science.
“At SARAO, we are quite deliberate about this. We are not only here to build and operate telescopes. Part of our job is to make sure that the investment in astronomy also builds technology, people and capability across Africa. That includes technology development, commercialisation and human capital development.”
This would also mean benefiting underserved communities, strengthening national technical capacity and encouraging young people to pursue science, technology, engineering and mathematics careers.
International collaboration
MeerKAT also participates in very long baseline interferometry (VLBI) with the European VLBI Network, sharpening its resolving power and preparing for future SKAO-VLBI operations. NASA Earthdata defines VLBI as a “geometric technique that measures the time difference between the arrival at two Earth-based antennas of a radio wavefront emitted by a distant quasar. Using large numbers of time difference measurements from many quasars observed with a global network of antennas, VLBI determines the inertial reference frame defined by the quasars and simultaneously the precise positions of the antennas.”
“International collaboration in astronomy is not something we add after the technical work is done. Often the collaboration is part of the instrument. No single telescope, institution or country has everything needed to answer the questions we are now asking. We have to combine instruments, expertise, data, engineering and ideas,” said Molamu.
Plans are underway for South Africa to host the mid-frequency component of the SKA, one of the most ambitious scientific instruments ever undertaken. For Molamu, its significance extends well beyond hosting a telescope.
“It means developing and sustaining the engineering, digital infrastructure, computing, skills and industrial capability required to participate in a project of this scale. It also means that South African engineers and scientists are not simply users of the next generation of astronomy infrastructure. We are helping to build it,” she added.
The MeerKAT Extension will add 14 SKA-design dishes, extend baselines to 17 kilometres and introduce a new graphics processing unit correlator. The international partnership has also contracted SARAO to deliver a digitiser system – evidence of sought-after South African expertise.
“We are not only building the next telescope. We are building the capability to participate in what comes after it,” Molamu said.
Opportunities for communities
According to Molamu, progress must be visible on the ground. The Karoo’s telescopes look through cosmic time and its rocks preserve Earth’s history, but communities live between those histories.
“At SARAO, we think about that impact quite broadly. It is skills. It is businesses getting the opportunity to do difficult work. It is research and technology. And it also has to be about the communities around these facilities.”
Molamu believes astro-tourism could extend beyond telescope visits to embrace the Karoo’s science, landscape, natural history, culture and people.
“If large scientific infrastructure is going to transform a place, then the people who live there should have a real opportunity to participate in the value that grows around it,” she said. ❖
SARAO – a facility of the National Research Foundation – is responsible for managing all radio astronomy initiatives and facilities in South Africa.