Posts: 10,227
Threads: 345
Joined: Apr 2009
Thanks, Opihikao. In related news it does seem a decision about the TMT's final location is not far away:
http://optics.org/news/7/8/21
" In Edinburgh, Li admitted that the eventual location of the TMT could affect its precise design, given the different weather and wind conditions to be found at alternative proposed mountain-top sites in the Canary Islands, Baja Mexico, and Chile, compared with Mauna Kea."
"Dynamic Structures, which is part of the diversified steel conglomerate Empire Industries, said it expected to complete the enclosure design over the next 20 months, which suggests that the consortium is confident that the location issue will soon be resolved."
This was also published today regarding the possible site at Ladakh in India (a link to Business Standard, which seems to be an Indian newspaper):
http://goo.gl/9JvRtg
" The necessary site-specific details have been submitted to the TMT alternate site selection team. Hanle site has lower seeing values of 0.9-1.2 arc sec as compared to the alternate sites in Chile and Canary Islands of Spain (La Palma) which have seeing values of 0.55 arc sec. Thus, scientifically, Hanle has less advantageous characteristics for hosting a mega telescope like the TMT in comparison to the other alternate sites, the reply added."
That quote makes more sense if you replace the word "lower" with "poorer".
Posts: 10,227
Threads: 345
Joined: Apr 2009
Eric1600,
"I was rounding a bit. Large power transformers (around 100 MVA and larger) may attain an efficiency as high as 99.75% whereas the low end of the scale for power transformers (100 MVA to 1 MVA) is about 98.5%"
Thanks, I'll have to do some extra reading. That's a stunningly high efficiency!
Posts: 3,202
Threads: 108
Joined: Jun 2010
I doubt we'll have giant optical telescopes in space by 2035. Pretty sure the ground based ones will be useful until we can launch/manufacture the space equivalent.
Posts: 664
Threads: 67
Joined: Mar 2016
quote:
Originally posted by pahoated
Mauna Kea has a mean seeing value of 0.88 so Chile and Canary island with 0.55 have much better seeing values. The air above Hawaii may be clearer but there is a lot more turbulence. The lower end of the India seeing value is comparable to Mauna Kea but they may have much less upper atmosphere turbulence on average.
With adaptive optics turbulence is a non-issue. However clarity can not be compensated for and is a much bigger problem.
quote:
The average number of viewing days at Atacama is 300 days per year. On Mauna Kea, it is 240 days per year. Considering ground based optical telescopes are automatically 50% efficient (~12 hours per night), that means a telescope at Atacama can be viewing 3,600 hours per year versus Mauna Kea with 2,880 hours per year.
Wrong. It's 315 days, not 240. http://www.maunakea.com/faq.htm
(Updated 2/14) Our latest in-house statistics show that Mauna Kea has been over the last few years clear enough for astronomy and a scenic sunset an average of 315 nights a year.
quote:
The fact ground based optical telescopes are so sensitive to wind, humidity, ground temperature, light pollution, many other uncontrollable variable limitations, only highlight these are the twilight years for them.
Actually all of these things are easily controlled and the big island has a long history of making sure light pollution is not a factor, unlike some of the other locations. Your incorrect facts do not support your wish that telescopes are obsolete in any way.
quote:
The Mauna Kea observatories are planned to be shut down by 2035, and that does look like a reasonable timeframe for the coming obsolescence of the ground based optical telescope. The existing ones will continue to be upgraded until then but the era of new, giant optical telescopes is definitely coming to an end.
2035 is just the end of the lease. For example the TMT people are betting that once the world sees the imagery there will be wide spread support for renewing the lease. Much like Hubble's mission extensions have occurred.
The end of ground based astronomy is only in your pahoa-head ted.
Posts: 820
Threads: 106
Joined: Mar 2006
The Mauna Kea Science Reserve Lease is slated to expire in 2033. There is a separate lease for the Hale Pohaku support facilities, which expires in 2041. The is plans to extend the lease, but this may turn in a bigger hornets nest than the TMT debacle.
Posts: 14,115
Threads: 424
Joined: Aug 2012
until we can launch/manufacture the space equivalent
Cutting NASA's budget will get us there for sure!
Posts: 10,227
Threads: 345
Joined: Apr 2009
Pahoated claimed:
" Mauna Kea has a mean seeing value of 0.88 so Chile and Canary island with 0.55 have much better seeing values. The air above Hawaii may be clearer but there is a lot more turbulence. The lower end of the India seeing value is comparable to Mauna Kea but they may have much less upper atmosphere turbulence on average."
Although there are small variations from site to site, Mauna Kea's median natural seeing is approximately 0.5 arcseconds.
http://www.cfht.hawaii.edu/Instruments/O...ec_2).html
https://www.eso.org/gen-fac/pubs/astclim...nakea.html
http://subarutelescope.org/Observing/Tel...ty/Seeing/
http://www.ukirt.hawaii.edu/telescope/se...g2001.html
http://adsabs.harvard.edu/full/1987PASP...99..560B
http://adsabs.harvard.edu/full/1989PASP..101..436R
Posts: 1,930
Threads: 71
Joined: Jun 2012
What bugs me about TMT is what does it do for me, as a resident of this island? So far, it has done diddly-squat positively and truckloads negatively.
I am starting to notice TMT Corp. is using the other observatories on Mauna Kea and local people as pawns in the minds-and-hearts campaign. I don't see anybody from TMT Corp. directly on stage. It really adds to the impression TMT is a malihini project for malihini, the mountain on the island is choice, the people living here are inconsequential. It would seem like the other observatories would back off from being the cheerleaders for TMT, since their position isn't threatened. What exactly is TMT going to do for me that hundreds of other observatories aren't already doing?
Here is an example of one upgrade to an existing observatory going on. It will be using a single optical fiber as a steerable telescope. The steering is by a really cool tiny robot arm. There are 5,000 of these. No environmental impact, capability increased a thousand-fold. It will be searching to 23 billion light-years. Ground based optical scopes are maxing out at 13.4 billion light-years. Welcome to relativity astrophysics. This is just one of the developments going on.
http://spie.org/newsroom/6531-robotic-fi...instrument
Robotic fiber positioners for dark energy instrument
http://newscenter.lbl.gov/2016/08/09/3-d...ion-phase/
3-D Galaxy-mapping Project Enters Construction Phase
*Japanese tourist on bus through Pahoa, "Is this still America?*
*Japanese tourist on bus through Pahoa, "Is this still America?*
Posts: 3,202
Threads: 108
Joined: Jun 2010
High paying jobs on island, those people spend in the local economy, those businesses patronize other local businesses, and everyone goes to lunch. Every dollar from science is one less we need from tourism or walmart.
I suppose you want to know what the sun does for you, aside from giving you sun burns. Stupid malihini sun...
Posts: 820
Threads: 106
Joined: Mar 2006
What ultimately happens to the TMT project, will affect the otherb telescope facilities on Mauna Kea. If the TMT decides to relocate their facility elsewhere, it will cause investment in the other existing telescopes to dry up. The backers of the other telescopes will think twice about upgrading their facilities in such a hostile environment.
In addition, the other elephant the room is looming end of the science reserve master lease. If the TMT is able to construct its facility, there will be much stronger case to go through lease extension process. However. if the TMT is built elsewhere, all bets are off.
|
