March 9th, 2017, Published in Articles: EE Publishers, Articles: EngineerIT

by Hans van de Groenendaal, features editor, EngineerIT

 

The hydrogen epoch of re-ionisation array (HERA) radio telescope, which will probe the 3D structure of the universe, was awarded a grant from the Gordon and Betty Moore Foundation in the US to the value of $5,8-million, equivalent to approximately R75-million. HERA is located only a few kilometres from the MeerKAT radio telescope in South Africa’s Northern Cape province.

This innovative radio telescope will be instrumental in detecting the distinctive signature that would allow astronomers to understand the formation and evolution of the very first luminous sources: the first stars and galaxies in the universe – a period the scientists call the epoch of reionisation (EoR).

With the grant, the sensitivity of the array can be increased, enabling it to potentially detect signals coming from a time before the EoR in the history of the universe, the cosmic dawn, roughly 400-million years after the big bang. HERA will be able to access a cosmological signal roughly 100 000 times fainter than emissions from the Milky Way and nearby galaxies.

The construction of HERA started in 2015 and already 35 of the 14 m diameter dishes have been erected. In September 2016, the National Science Foundation (NSF) invested $9,5-million (R124-million) in the project and HERA was granted the status of a Square Kilometre Array (SKA) precursor telescope. The NSF funding allowed the array to expand to 240 radio dishes by 2018. The new funding increases the sensitivity of HERA by adding a further 110 dishes – 350 dishes in total.

Dr. Gianni Bernardi, SKA South Africa senior astronomer working on HERA, says that this increase in collecting area provides the sufficient sensitivity to attempt imaging large ionised bubbles rather than measuring only their statistical properties. Using this next-generation instrumentation for 21 cm cosmology – the wavelength of neutral hydrogen gas radio waves – HERA will probe the 3D structure of the universe during the very first appearance of stars, galaxies and black holes. This first generation of hot massive stars and black-hole binaries filled the intergalactic medium with X-rays.

According to Dr. Bernardi, observations at the lowest radio frequencies (< 100 MHz), allows for observations of the epoch that precedes cosmic re-ionisation where X-rays are expected to have heated the intergalactic medium. As X-rays are expected to be generated by accretion on black holes, Dr.Bernardi says that observations of this epoch will directly probe the properties of the first black holes formed in the universe.

HERA comprises a close-packed array of fixed parabolic reflector elements (dishes). The centre position of each dish is determined by the placement of a concrete hub. These hubs constrain radial PVC spars, tensioned into approximate parabolas against a rim, which is supported by utility (telephone) poles. Welded mesh panels are installed on these spars to form the reflector surface.

According to project engineer Kathryn Rosie, five local residents, who have been part of the HERA construction crew since 2015, have recently taken up positions as HERA team leaders in anticipation of the crew expansion for the “big build” this year. In addition to maintaining construction activities, this crew now has the added responsibility of training new construction team members. The build-out plan for the next construction phase sees five teams working in parallel to achieve the build targets, which require an output of approximately 100 dishes per year. It is expected that the entire crew contingent will be made up of Karoo residents. Rosie says that over R1,7-million has been spent thus far with local suppliers in the Karoo to purchase the material with which the telescope is being built.

SKA South Africa MD, Dr. Rob Adam, says that the SKA is progressing very well and this additional funding injection is evidence of the confidence the international community has in the excellent skills and results we are demonstrating. According to Dr. Adam, SKA SA remains committed to ensuring that local communities and businesses benefit from the construction of radio telescopes in the Karoo, and HERA is a fine example of that.

It is fitting that the man who originated Moore’s Law, Gordon Moore, is affiliated to the SKA project through this Gordon and Betty Moore Foundation grant. Gordon Moore is the chairman and co-founder of the Gordon and Betty Moore Foundation. Gordon Moore predicted in 1965 that there will be a steady shrinking of computer chip circuitry. This idea that transistor density would double with each new generation of technology is referred to as the Moore’s Law. The HERA project is a collaboration of Arizona State University, Brown University, Cambridge University, the Massachusetts Institute of Technology, and the National Radio Astronomy.

Related Articles

South African Government COVID-19 Corona Virus Resource Portal

Ministerial determinations propose 13813 MW of new-build by IPPs, none by Eskom

Crunch time for South Africa’s national nuclear company, Necsa

Dealing with the elephant in the room that is Eskom…

Interview with Minerals & Energy Minister Gwede Mantashe