Author Topic: Deflecting or destroying dangerous asteroids  (Read 9618 times)

Offline as58

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Re: Deflecting or destroying dangerous asteroids
« Reply #120 on: 08/05/2017 09:14 PM »
... if you can build a >10m space telescope for the cost of NEOCam, you should probably submit a proposal to NASA.
NEOCam is planning a 0.5m primary, which if reground as a secondary would suggest a primary collecting diameter around 7m and associated 25% increase in launch mass. But why would I submit such a proposal to NASA considering the state of their current programs (SLS, ISS, Commercial), their planned ones (DSG and..?) and their dysfunctional administrative system (program management, selection, budgeting, etc)? If they got better, better options like this and others will both become available and be selected. For now it's still better than ESA, but still not worth the time nor high expectations.

Could you please describe how this telescope design that you keep alluding to would work?

Online RonM

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Re: Deflecting or destroying dangerous asteroids
« Reply #121 on: 08/05/2017 09:20 PM »
NEOCam is planning a 0.5m primary, which if reground as a secondary would suggest a primary collecting diameter around 7m and associated 25% increase in launch mass.

No, that's not how it works. A 7m mirror would have nearly 200 times the surface area of a 0.5m mirror. How could you possibly build a 7m telescope that only masses 25% more than a 0.5m? Hubble "only" has a 2.4m mirror.

We don't need large space telescopes to find asteroids. Multiple NEOCam missions would be nice to speed up the survey.

Please do some research before you post.

Online hop

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Re: Deflecting or destroying dangerous asteroids
« Reply #122 on: 08/05/2017 09:45 PM »
Could you please describe how this telescope design that you keep alluding to would work?
Seconded, but in it's own thread, please!

Offline Jim

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Re: Deflecting or destroying dangerous asteroids
« Reply #123 on: 08/05/2017 09:54 PM »
[. But why would I submit such a proposal to NASA considering the poor state of their current programs (SLS, ISS, Commercial), their planned ones (DSG and..?) and their dysfunctional administrative system (program management, selection, budgeting, etc).
If they got better, better options like this and others will both become available and be selected. For now NASA's still better than ESA, but still not worth the time nor effort or expectations.

Wrong on all counts.  All unsupported opinion.
There is no "poor state" of the science programs.  It is healthy.

"dysfunctional administrative system"? You really don't know what you are talking about.  The proposers run most of the missions.

NASA is the only show around.  ESA doesn't even come close and has worse "problems".


Online hop

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Re: Deflecting or destroying dangerous asteroids
« Reply #124 on: 08/05/2017 10:22 PM »
NEOCam is planning a 0.5m primary, which if reground as a secondary would suggest a primary collecting diameter around 7m and associated 25% increase in launch mass. But why would I submit such a proposal to NASA considering
If you can't propose it yourself, there's a whole lot of people in the field who would love to be able to propose a 7m telescope on a Discovery budget! Or better yet, a 2m telescope on an even smaller budget.

NEOCam was proposed for Discovery, which is a competitive, PI-lead, cost capped program. That means the PI proposes the mission, NASA and outside experts evaluate the technical credibility and science value, and if it's selected, NASA pays for it. NEOCam wasn't selected in the last round, but it did get additional development funding. An otherwise equivalent, much larger telescope for similar cost would be very competitive indeed.

Furthermore, the community is currently studying concepts Hubble follow-on visible / near IR  / UV telescope in the 8-16 meter class (ATLAST / HDST / LUVOIR etc.) This is expected to be flagship cost (i.e. several to many billions) mission. If it could be done on a Discovery budget (~0.5 billion) that would be a game changer for the entire field.

(but again, if you want to discuss how you think this can be done, it really deserves it's own thread)
« Last Edit: 08/05/2017 11:15 PM by hop »

Offline Propylox

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Re: Deflecting or destroying dangerous asteroids
« Reply #125 on: 08/06/2017 12:55 AM »
... Hubble "only" has a 2.4m mirror.
Sorry, ft to m SNAFU. 43ft ~ 6.5m for Kepler , 110ft ~ 33.6m for WFIRST , 294ft ~ 91m for JWST

Point being very large telescopes aren't the financial and technical hurdle so many assume. And if such telescopes were available, they'd be requested for missions such as asteroid detection. Which is in itself proof that the current proposals aren't based on mission demands, but the low bar of beggars. So I ask what's the point of a project that will take forever, be incomplete when "finished" while not addressing the most likely source of impacts and only one we can stop: small meteors - especially when good options are available?
If you're going to do something, do it right. Don't offer snails, call it gourmet and demand hundreds of $millions.

...ESA doesn't even come close and has worse "problems".
On that, we're in complete agreement. I'd add it's not just their space program, but entire scientific endeavours.
« Last Edit: 08/06/2017 01:00 AM by Propylox »

Online gongora

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Re: Deflecting or destroying dangerous asteroids
« Reply #126 on: 08/06/2017 01:17 AM »
... Hubble "only" has a 2.4m mirror.
Sorry, ft to m SNAFU. 43ft ~ 6.5m for Kepler , 110ft ~ 33.6m for WFIRST , 294ft ~ 91m for JWST

Point being very large telescopes aren't the financial and technical hurdle so many assume. And if such telescopes were available, they'd be requested for missions such as asteroid detection. Which is in itself proof that the current proposals aren't based on mission demands, but the low bar of beggars. So I ask what's the point of a project that will take forever, be incomplete when "finished" while not addressing the most likely source of impacts and only one we can stop: small meteors - especially when good options are available?
If you're going to do something, do it right. Don't offer snails, call it gourmet and demand hundreds of $millions.

...ESA doesn't even come close and has worse "problems".
On that, we're in complete agreement. I'd add it's not just their space program, but entire scientific endeavours.

What the hell are you talking about?  What are those numbers in your post supposed to mean, and why do you think it's trivial to build space telescopes an order of magnitude larger than anything that's been flown?

Offline gospacex

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Re: Deflecting or destroying dangerous asteroids
« Reply #127 on: 08/06/2017 08:49 AM »
NEOCam is planning a 0.5m primary, which if reground as a secondary would suggest a primary collecting diameter around 7m and associated 25% increase in launch mass.

No, that's not how it works. A 7m mirror would have nearly 200 times the surface area of a 0.5m mirror. How could you possibly build a 7m telescope that only masses 25% more than a 0.5m? Hubble "only" has a 2.4m mirror.

We don't need large space telescopes to find asteroids. Multiple NEOCam missions would be nice to speed up the survey.

Please do some research before you post.

It's some 5th time you and others said this to him. He will not.

Online whitelancer64

Re: Deflecting or destroying dangerous asteroids
« Reply #128 on: 08/07/2017 02:55 PM »
This is the Dunning–Kruger effect, he obviously thinks he knows what he's talking about, but he doesn't actually know enough about these topics to know that he's wrong.
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Online Lar

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Re: Deflecting or destroying dangerous asteroids
« Reply #129 on: 08/07/2017 08:42 PM »
Let's not psychoanalyze each other, k? Some posts ought to be edited or deleted.
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Online meberbs

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Re: Deflecting or destroying dangerous asteroids
« Reply #130 on: 08/09/2017 12:44 AM »
One of the points I have been trying make lately is that it takes a space telescope to really ascertain asteroid threats.  JWST is so late and overcost ($10B+ and climbing) it really makes you wonder about the impact Will be if it fails.

There is no way the telescope of JWST is 91m. More like 6.5m.

Does JWST have specific goals to monitor asteroids or inbound comets that are Earth grazing?  I always (or 17 years ago) got the impression it was to be used for deep sky surveys using a variety of IR cameras/sensors.  Are there dedicated space telescopes for asteroids flying now???
JWST is really irrelevant to the thread. While it is capable of observations inside the solar system, it is really not designed for searching for NEOs, and in most cases is incapable of pointing in a way to see them. It could be used for some IR characterization of comets or certain NEOs, but even without the pointing restrictions, it would be a terrible choice for a survey to discover new objects. It is intended for long dwells at objects within a narrow field of view. Details about the intra-solar system capabilities are at the link below.

https://jwst.nasa.gov/faq_solarsystem.html

As for space based telescopes, there was the NEOWISE mission, and NEOCAM is in the planning stages. JWST is a gigantic, complicated telescope mostly for looking far away. JWST is just not a relevant baseline (cost, schedule, or complexity) for discussing space based telescopes for NEO asteroid searches.

P.S. you are right about the size of JWST, but seem to have misstated the cost, $10 billion is the current estimate of the final bill including international contributions and operation, and this number hasn't really changed since the last re-plan years ago. It is not the amount that has been spent so far, and it is not climbing.

Offline Nomadd

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Re: Deflecting or destroying dangerous asteroids
« Reply #131 on: 08/09/2017 12:56 AM »
Let's not psychoanalyze each other, k?
Why do you think you feel that way?

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