<div style="text-align: justify; "><span style="font-size: 1rem;">One of the grand scientific projects of the 21st Century begins its construction phase on Monday.</span><br></div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The Square Kilometre Array (SKA) will be the largest radio telescope in the world when completed in 2028.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">Split across South Africa and Australia, with a headquarters in the UK, the facility will address the biggest questions in astrophysics.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">It will perform the most precise tests of Einstein's theories, and even search for extra-terrestrials.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">Delegations from the eight countries leading the project are attending ceremonies in the remote Murchison shire in Western Australia and in the Karoo of South Africa's Northern Cape.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">When the festivities are over, the bulldozers will move in.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">"This is the moment it becomes real," said Prof Phil Diamond, director general of the Square Kilometre Array Organisation.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">"It's been a 30-year journey. The first 10 years were about developing the concepts and ideas. The second 10 was spent doing the technology development. And then the last decade was about detailed design, securing the sites, getting governments to agree to set up a treaty organisation (SKAO) and provide the funds to start," he told BBC News.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The initial architecture of the telescope will incorporate just under 200 parabolic antennas, or "dishes", as well as 131,000 dipole antennas, which look a little like Christmas trees.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The aim is to construct an effective collecting area measuring hundreds of thousands of square metres.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">This will give the SKA unparalleled sensitivity and resolutions as it probes targets on the sky.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The system will operate across a frequency range from roughly 50 megahertz to, ultimately, 25 gigahertz. In wavelength terms, this is in the centimetres to metres range.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">This should enable the telescope to detect very faint radio signals coming from cosmic sources billions of light-years from Earth, including those signals emitted in the first few hundred million years after the Big Bang.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">One of the SKA's great quests will be to trace the full history of hydrogen, the most abundant element in the Universe.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The telescope should be able to detect hydrogen's presence even before great clouds of it collapsed to form the first stars.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">"The SKA is going to contribute to so many areas of astronomy," said Dr Shari Breen, the observatory's head of science operations.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">"One would be these 'fast radio bursts' that have been detected. These things output the equivalent of an entire year's worth of energy from our Sun in just a fraction of a second. And we have no idea what they are. How is that possible? Hopefully the SKA will have an answer."</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The telescope is being built in areas already used for radio astronomy on a smaller scale.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">To expand these sites, however, has required various land agreements, with farmers in the Karoo; and with the Wajarri Yamaji, the Aboriginal title holders in the Murchison.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">The Wajarri community have organised Monday's celebration to inaugurate the SKA.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">Various procurement contracts will be announced around the ceremonies.</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">These will take the total financial outlay to date to just under €500m (£430m) - out of an expected final construction budget of €2bn. BBC</div><div style="text-align: justify; "><br></div><div style="text-align: justify; ">bnbd24/kh</div>