Space is the place – A review of July’s SciBar

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Professor Michael Merrifield is worried. He’s concerned that astronomy is reaching the end of the line, that it’s “doomed”. Surely, astronomy has always thought like this though, Even Galileo must have assumed that the discovery of the heliocentric solar system was the end of the story.

 

However, astronomy has been making quite a splash recently:

 

  1. New Horizons

The probe that has reached Pluto is sending data back at 300 bits per second (for those that can remember dial-up internet, even that reached the heady speed of 56K bits per second) This means that it will take 18 months to transmit all of its data back to Earth.

It has already sent back some fascinating images though. We already knew that Pluto also has an atmosphere which changes depending on how close it is to the sun. We now know that Pluto has mountains, some of which are 20,000 feet tall, which was totally unexpected.

 

  1. Kepler

This telescope monitors a few hundred thousand stars to measure their brightness. It is looking for planets – when one obits in front of a star it blocks out approximately 1% of the light from the star. Kepler has been in the news recently because it discovered the planet Kepler 452b, which has been dubbed Earth 2.0.

It is in the so called habitable zone and in fact is almost exactly the same distance from its star as we are from the sun. It’s larger and older than the Earth and while people are excited about the discovery of Earth 2.0, they need to remember that sequels are never as good.

 

  1. ALMA

This radio telescope array in Chile has over 60 dishes. It has found carbon as a gas in a galaxy from just 800M years after the big bang. The gas is falling in to form new stars. Unlike the above two, this hasn’t really hit the headlines as the images aren’t quite as good but this is arguably the more exciting news.

 

The immediate future is also looking bright. In 2018, the James Webb telescope launches. It’s an optical IR telescope that has a mirror made of beryllium, which doesn’t change shape or size in cold temperatures. It’s big enough to be able to see back in time to when galaxies were forming.

There is also a huge telescope being built in Chile. The EELT should be online in 2025 and it features a 39 metre primary mirror. They have already levelled the top of a mountain in preparation and to give an idea of how big it’s going to be, the dome is set to be constructed by a company that specialises in building football stadia. Not only does that mirror have to be built perfectly, it has to stay perfect even when it’s effected by wind and gravity.

Hubble’s law tells us that the most distance objects are travelling the fastest. Calculations show that they could be speeding up by as little as 0.5cm/second per year. The EELT will be so sensitive it will be able to detect changes of around 5cm/second. So, after 10 years, we should be able to tell if the expansion of the universe is speeding up and hence potentially prove the existence of “dark energy”

Unfortunately, the Overwhelmingly Large Telescope, which would have had a 100m mirror, never made it past the planning stage.

There are around 15 current generation large telescopes around the world. There are also around 10,000 professional astronomers. 1,000 or so of these regularly use those telescopes. However, in the future there will only be three next generation telescopes (this is mainly due to the cost of building them)

How will those 1,000 astronomers cope with fewer resources? Are there too many astronomers?

Why are telescopes increasing in size? The Hubble space telescope has a mirror that is 2.4m in diameter. The James Webb will have a mirror that will be 6.5m in diameter. The bigger the telescope, the sharper the image.

On the ground, the Earth’s atmosphere can affect the image. This obviously isn’t an issue for space telescopes. However, we won’t be able to send astronauts up to the James Webb as it will be too far away. It will be twice as far away from the Earth as the moon is, at the Lagrange point, which is perfect for sensing in the IR spectrum. Whereas it was possible to keep repairing and upgrading the Hubble, this means that the James Webb only has a 5 year life span.

Hence, the future is already being designed – the High Definition Space Telescope will have a primary mirror that is 11.7m in diameter. Not only could this see actual planets around a star but it could also look for biomarkers in the atmosphere of those planets to see if there is life on them.

The James Webb space telescope will cost around $2B just for the telescope. Professor Merrifield says that a reasonable estimation for the total cost (including actually launching it into space, instruments, etc) is around three times the cost of the telescope itself. The initial estimate for the High Definition space telescope is $3B. Hence it will probably end up costing closer to $10B

However, in 1997, when it was initially proposed, James Webb was estimated to cost just half a billion dollars. By 2013, that estimate had grown to $8.8B. So, how much with the HDST actually cost?

This year, half of NASA’s astrophysics budget has gone on the JWST. All of NASA’s eggs are in one telescope basket. Since there is no guarantee that it will actually deploy from the rocket properly, and since no humans can go and fix it, this could be a potentially foolhardy decision. Instead of just building bigger telescopes, is it time to look at building smarter? For example, Kepler, mentioned above.

The other challenge on astronomy spending is, “what is the return on all of this investment?” Well, a spinoff from UCL has created a computer controlled mirror polishing machine. Not only can this be used to make mirrors for telescope but it can also be used to polish artificial hip joints. This doubles the life span of the joints from 20 years to 40.

 

For more information check out these YouTube channels:

https://www.youtube.com/user/sixtysymbols

https://www.youtube.com/user/DeepSkyVideos

 

Gav

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