First segments of Extremely Large Telescope have shipped to Chile

After 20 years of development, the first eighteen segments of Europe’s Extremely Large Telescope (ELT) have now shipped to Chile, with another 780 more segments to go.

The assembly of the telescope’s massive mirrors will take place over the next 4 years. This week, the first segments of what will be the main mirror – called ‘M1’ – arrived in Chile.

Once complete in 2028, these segments will create a primary mirror 40 meters across, about 131 feet, four times larger than the 10.4 meter Gran Telescopio in the Canary Islands, presently the largest telescope in operation.

Extremely Large Telescope in Chile marks halfway point in construction

The Extremely Large Telescope (ELT) has now celebrated the halfway point in its construction, with completion targeting 2028 when its 39-meter mirror will make it by far the largest telescope in the world.

The 39-meter diameter, or 127 feet or 1,535 inches, is about four times larger than the largest telescope that presently exists, the 10-meter telescope in the Canary Islands. By the time ELT begins operations however the 21-meter Giant Magellan Telescope (GMT) in Chile should also be in operation.

Sadly, the Thirty Meter Telescope (TMT) in Hawaii will likely not exist, even though it had intended to begin construction before ELT and GMT and be operational now. Leftist opponents in Hawaii have shut construction down now for almost eight years, with little signs of it ever proceeding.

Not that any of this really matters. In the near term, ground-based astronomy on Earth is going to become increasingly impractical and insufficient, first because of the difficulties of making good observations though the atmosphere and the tens of thousands of satellites expected in the coming decades, and second because new space-based astronomy is going to make it all obsolete. All it will take will be to launch one 8-meter telescope on Starship and ELT will become the equivalent of a buggy whip.

First six segments of Extremely Large Telescope cast

The first six mirror segments of the European Southern Observatory’s Extremely Large Telescope have been successfully cast.

These segments will form parts of the ELT’s 39-metre main mirror, which will have 798 segments in total when completed. The ELT will be the largest optical telescope in the world when it sees first light in 2024.

The 39-metre-diameter primary mirror of ESO’s Extremely Large Telescope will be by far the largest ever made for an optical-infrared telescope. Such a giant is much too large to be made from a single piece of glass, so it will consist of 798 individual hexagonal segments, each measuring 1.4 metres across and about 5 centimetres thick. The segments will work together as a single huge mirror to collect tens of millions of times as much light as the human eye.

The segments must now be cooled, then their surfaces ground and polished to the right shape. If all goes right, they will make more than 900 segments (with about a 130 as spares), manufactured to have the telescope operational by 2024.

ELT construction moves forward

The European Southern Observatory (ESO) today signed contracts for the construction of the mirrors and sensor for its Extremely Large Telescope (ELT).

At a ceremony today at ESO’s Headquarters four contracts were signed for major components of the Extremely Large Telescope (ELT) that ESO is building. These were for: the casting of the telescope’s giant secondary and tertiary mirrors, awarded to SCHOTT; the supply of mirror cells to support these two mirrors, awarded to the SENER Group; and the supply of the edge sensors that form a vital part of the ELT’s huge segmented primary mirror control system, awarded to the FAMES consortium. The secondary mirror will be largest ever employed on a telescope and the largest convex mirror ever produced.

The construction of the 39-metre ELT, the largest optical/near-infrared telescope in the world, is moving forward. The giant telescope employs a complex five-mirror optical system that has never been used before and requires optical and mechanical elements that stretch modern technology to its limits.

Meanwhile it remains unclear when and where the Thirty Meter Telescope (TMT) will be built.