We used to get around pretty good on railroads, too.

There are numerous discoveries that were made using math and limited observation techniques.  That doesn't mean we should limit ourselves to what was used decades or centuries ago.

We won't know what we will find until we find it, and technology that didn't exist 10 or 20 years ago might be the thing that makes those discoveries possible.

Old observatories are hindered by the limits of their generation.

New technologies in computers, software, electronics, and manufacturing can let us make mirrors better, lighter and more powerful than we could before.  The TMT is also a multinational venture, sharing the cost and the scientific brainpower of several nations to better enable the TMT's construction and use.

And old observatories might be able to "do that now", but the TMT will be able to do it at twelve times the resolution.  That's significant when tracking objects or monitoring the surface of Mars.

I'll try to answer your questions, I've been out of the loop for a few years but all the rationals still exist.
" Do we need TMT with Hubble and Keck at our disposal"
Hubble is nearly dead and is barely working, I think if one more Gyro fails it will be useless.
The replacement, The James Web space telescope is way over cost and they are having some
very real technical problems, I'm not sure they will every get over them.
Keck I and II are awesome facilities. Fairly up to date.
They had a mirror cracking problem I'm not sure they have fixed yet.
There are also limits as to what they can do to update the telescope itself
to deal with Keck's physical limitations eg wind shake. The summit gets very windy.

In Astronomy the more Photons you can gather
repeatedly on the same detector Pixel 13 micrometers( or less) across the better.
Keck is ten meters across. TMT is thirty meters across.  that is a significant increase in
area to gather photons.  TMT is also designed to compensate for problems large
telescopes like Keck, et al have.
The Astronomical community figured the billion dollar Plus cost of the TMT is  worth the effort.
India, China, Japan, Canada, et al seem to agree as they are heavily invested in the TMT.

Do we need the TMT?  In astronomy all you are doing is studying history.
Studying galaxies that may not exist anymore as their light took 13 billion years to get here.
What good does that do?
Why go to the moon?  Why go to Mars?

The answer is because somebody is willing to pay for it,
because they want it, not because they need it.
Personally I thought the TMT money would be better spent
eradicating cancer, but that isn't as sexy as finding binary
Black holes in a far off Galaxy.

Hope that helps some.

I know I upset you sometimes.
Perhaps you did not read all my comments closely.
TMT is not going to be used for Mars studies.
I was privy to the TMT Critical Design Review.
I know TMT engineering and science staff.
I know Keck staff.
I know Gemini staff.
I know CFHT staff.
I've worked with them.
I'll stop there as you may be able to figure out my real
name if I say more.

There are many space borne telescopes, like Hubble, that will out perform earth bound telescopes by a long shot. Sorry, I thought Keck was space based. My bad.....

Telescope?  What telescope?

As protesters pour into the cameras view atop the Saddle Road, Office of Hawaiian Affairs (OHA) Trustees
are reminding Governor Ige of OHA’s real goal—not stopping the proposed Thirty Meter Telescope (TMT)
but gaining control of thousands of acres atop Mauna Kea.

A July 12, 2019 letter to Ige signed by OHA Trustees Chair Colette Machado and Trustee Dan Ahuna yields
this nugget:

   As you know, OHA has no position on the siting of the TMT on Maunakea….

In a July 14, 2019 news release, Machado and Ahuna urge:

   We as a society must set aside our differences on TMT….

Machado and Ahuna attempt to co-opt the protesters--not as anti-Telescope ‘protectors’ but:

   “OHA beneficiaries and others who have long voiced concerns about the state’s decades-long mismanagement of
   Maunakea.”

And beneficiaries they are.  Many of the protesters are affiliated with ‘immersion schools’ and non-profits funded by OHA.

In a July 17 statement issued just as police began making the first arrests, OHA again attempts to co-opt the Mauna Kea
protesters:

   ...Regardless of your position on TMT, we must all agree with Gov. Ige’s 2015 statement that the state has “failed” Maunakea.

   OHA will continue to proceed with our lawsuit against the state and UH for their mismanagement of Maunakea. We
   continue to call for the state and UH to be held accountable as fiduciaries for our trust resources, and we demand that
   a new management structure is immediately installed for Maunakea.

Media consumers will be “pana po’o” over those statements.  After years of media-borne agit-prop, a Google search for “sacred
Mauna Kea” pulls up 7,460 results.  Reacting to the protests, a UH Manoa grad student “studying indigenous history and settler
colonialism” tells West Hawaii Today, “Money will never justify the desecration of sacred places.”

Wrong.

$50M should just about cover it.

OHA’s point person on Mauna Kea issues, Kealoha Pisciotta, in 2008, demanded $50M a year, saying “the rent is past due.”  In
2002, former OHA Trustees Chair Clayton Hee, demanded astronomers give OHA “$20 million in endowments.”

Governor Ige’s 2015 10-Point Plan for Mauna Kea included transfer to DLNR—not OHA-- jurisdiction of “all lands (over 10,000 acres)
not specifically needed for astronomy.”  The acreage is part of the ‘Ceded Land’ trust held by the State for five purposes delineated in
the Admission Act including, “support of the public schools and other public educational institutions.”

At the center of its current strategy, a 2017 lawsuit filed by OHA “requests the court to order the state to fulfill its trust obligations
relating to Mauna Kea and to terminate UH’s general lease for the mountain for breach of the lease’s terms.”

In the news release announcing the lawsuit, OHA also de-emphasized the telescope.  OHA Trustee Dan Ahuna is quoted:

   “This is not about any one telescope. This lawsuit is about addressing the state’s failure to manage the entire mountain for nearly
   half a century.”

   “It’s time to abandon any hope that UH is capable or even willing to provide the level of aloha and attention to Mauna Kea that it deserves. 
   We need to come together as a community to completely re-think how we care for the mauna, and that starts with cancelling the university’s
   master lease.”

With the current master lease set to expire in 2033, UH lease renewal efforts are again underway after stops and starts going beck to 2013. 
The UH Regents will be considering new administrative rules for Mauna Kea at their August 22, 2019 meeting.

How can OHA be trusted as a land manager given its mis-management of Waimea Valley and other assets?

In January, 2017 lawyers for OHA’s limited liability corporations argued that “Sole title to the land comprising Waimea Valley was transferred
to Hi’ipaka LLC (by OHA) in 2007.  The State does not own the valley nor any of Hi’ipaka’s other assets….”   Rejecting a UIPA open records
request from Hawai’i Free Press, OHA’s LLCs pursued that line of reasoning, claiming they were not state assets--and therefore immune to
UIPA--until Honolulu First Circuit Court Judge Jeffrey Crabtree rejected their claims in his June 25, 2019, “Finding of Fact and Conclusions of
Law.”

For nearly a year, OHA insiders have lied to the legislature and stonewalled an audit of their secretive LLCs—thus placing OHA’s legislative
funding at risk.  When Trustee Keli’i Akina challenged this, the other trustees voted to “investigate’ him for ‘disloyalty’. 

OHA once had a deal to support TMT in exchange for money—they welched on it when the 2015 protests began.

OHA has no position on the siting of the TMT on Maunakea

http://www.hawaiifreepress.com/ArticlesMain/tabid/56/ID/23903/Machado-OHA-has-no-position-on-the-siting-of-the-TMT-on-Maunakea.aspx?utm_source=July+21%2C+2019+News+from+HawaiiFreePress++&utm_campaign=July+21%2C+2019+Email+&utm_medium=email

TMT should sue the state for all the expenses and time wasted and go build the TMT in the Canary Islands, which was their 2nd choice.

2nd draft choice, but was it as good or not even close to mauna kea?

Sent from my SM-G950U using Tapatalk

Not as good.  Mauna Kea is about  the best place in the world to build a telescope.  Meanwhile, HNN says 2000 people were up there this weekend.  Large protests taking place in various cities in the US.  A large one in Waikiki this past weekend.  Like I said in the beginning, this should have been nipped in the bud.  LEO should have been in place the Saturday before and not allowed anyone one to walk or drive on the Access Rd and certainly not allow those tents to be erected.

The only question all along has been: Has this "strategy" by the government been due to incompetence and malfeasance, or due to the intent to aid and abet the racist criminals?

Trump should come out in support of the protesters.  That would throw Democrats into full insane meltdown mode.  It would be hilarious.

that would be hilarious. The protestors wuould probably flip and say F&CK TRUMP. He is against science. He will get blamed for not getting the telescope built

The problem with space-based is the cost of maintenance, repairs and upgrades.  We stopped launching space shuttles in 2011.  We'd have to out-source the missions to other countries or private space companies.

Cost to build it is another problem.  Ten billion for the James Webb telescope vs one billion for TMT

According to the specs, the TMT will offer TWLEVE TIMES the resolution of the best telescope in the world today. 

nitpicking here, but the Extremely Large Telescope (ELT) currently being built in Chile by the European Southern Observatory is 39 meters, which is obviously bigger than TMT, so TMT would already be smaller if it were to be built

https://en.wikipedia.org/wiki/Extremely_Large_Telescope

Though I realize that TMT would supplement the ELT because ELT is in the Southern hemisphere and TMT would be in the Northern Hemisphere.

Lots of technical and mechanical issues to solve the larger the mirror gets.  ELT original plan was for 100m primary mirror, but the segments were too large to transport over Chile's roads to the construction site. 

Two mirror panels are removed and cleaned on a daily rotating basis. Monitoring systems look for variations of curvature due to wind and weight distribution when the mirror moves.  They have to be adjusted automatically to maintain a perfect shape.  The larger the mirror, the more difficult that job becomes.

Increasing the size brings new problems and challenges to solve or mitigate.  Until they are built and working, all we can do is trust the designers and testers didn't overlook something significant, like they did on the Hubble mirror.