The future of Mauna Kea astronomy vs. space

[TomK]

Thought it best to separate this from the Bill 2024 thread, but someone mentioned in that thread:

"I also think ground based astronomy is a phase that's poised to give way to space. And Mauna Kea's status as a premier location for astronomy is passing to the heavens themselves."

This isn't true, but I thought I'd start this thread to allow that person to post their side of the story and tell us why he or she believes telescopes on the ground are poised to give way to space without having to discuss the management of Mauna Kea. I'm also more than happy to answer genuine questions about why ground-based astronomy is here to stay for decades, whether in Hawaii or not.

[kalianna]

Hereʻs a genuine question: While I understand that the telescopes we have on earth will be useful for a long time, I wonder why we should devote our telescope-building dollars to building more earth-based telescopes instead of investing in space telescopes, which you imply (I think) are the future of the field.

[TomK]

Hi kalianna,

Good question and I'll try and answer as briefly as I can; I'll expand later if you want.

The answer to your questions is that in an ideal world we should do both because ground and space-based telescopes complement each other. Space telescopes can observe at certain wavelengths that are impossible from the ground due to absorption by certain species of molecules in our atmosphere (e.g., CO, CO2, CH4, and to some extent, H2O). Space avoids looking through the atmosphere, and if you want to observe those molecules in space, at least at optical or infrared wavelengths, it has to be done from space or very high up in the atmosphere, say from an airplane.

However, launching observatories into space is horribly expensive and also comes with a lot of risks. For instance, the JWST (the "successor" to the Hubble), which is making the news right now as it starts to become operational, will be a game-changer but cost roughly $10 billion. The TMT, which will be more capable at other wavelengths, is currently estimated to cost $2.5 billion. The lifetime of the JWST will be roughly ten years before it runs out of fuel whereas the TMT can remain operational for decades. In addition, the JWST can't be upgraded or repaired, the TMT can be.

So, the JWST will do stuff that can't be done from the ground but only for a relatively short time, but the gound-based telescopes will continue to do things the JWST can't do and do them for much longer as well as carry out complementary observations of the same objects that the JWST observes.

Essentially, there is a need for space-based astronomy, but those missions are to do things the ground-based observatories cannot do and vice-versa, ground-based observatories will make discoveries space-based telescopes can't make and do it with much less expense and risk.

[kalianna]

Great! Thanks.

[TomK]

My pleasure. There's a lot more stuff I could have covered and explained but I don't have the time to write an essay right now! However, I'm happy to discuss more on this topic if you want.

[HawaiiEV]

Space telescopes cannot replace ground telescopes, including the radio telescopes Tom worked with, as he said the technologies all compliment each other so they can look at a wider picture of the universe. Space telescopes also have issues with their observations.