August 2015 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] Last night's lecture
by Joe Bauman 12 Dec '18

12 Dec '18

Brent, speaking of the ISS, I have wondered if it could be put into an orbit that continuously cruised between Earth and Mars. When it swung by Mars it could drop off and retrieved crews. I don't see how the radiation would be any worse than the ISS crews are already exposed to. ------------------------------ On Wed, Feb 25, 2015 8:18 AM MST Brent Watson via Utah-Astronomy wrote: >I attended the lecture last night on trajectories. It was really a good, stimulating talk. Thanks for passing the word along. >There were some interesting side comments made about our launch capabilities and the Mars One effort. Mr. Adamo was not at all enthusiastic about the Mars One effort. His opinion is that the effort is doomed because there is not really a way to assure that folks going there would be safe - primarily from radiation. He has done some work with a former flight surgeon on designing a spacecraft to go to Mars. Their result is that in order to get sufficient shielding (using a water jacket), the spacecraft's mass would be around 380 metric tons. That is for a small crew, probably only about 5 members. For a point of comparison, the ISS mass is 400 metric tons. He made the comment that an astronaut who made this trip could only go to space once in this craft, and then he would be at the limit of radiation exposure for his life. The NASA limit is an increased risk of developing cancer of 5%. >That brings us to our current launch capability. Our latest heavy lift rocket - the one we are currently developing - will have the capability to lift 130 metric tons to a very low earth orbit. So low, in fact, that it would burn up at perigee. The Apollo 17 Saturn 5 rocket lifted 140 metric tons into earth orbit -- higher than the new rocket will go. (I am sorry, but my mind will not allow me to recall the name of our currently being designed rocket.) Recall that it took several dozen shuttle launches to assemble the ISS. The Mars One vehicle would require either a hugely more massive launch rocket or a similar effort to build the craft. >As I mentioned, it was a very intellectually stimulating lecture and did involve several ordinary differential equations. They were nicely explained in English by Mr. Adamo. This was the first time I have seen some real math put to Kepler's laws. There were many charts showing what it takes to leave the earth and go to the moon or Mars. It was a very well done lecture. >The above is my recollection of the lecture, and may not actually represent the opinions of Mr. Adamo. It is only my interpretation of what he said. He knows his stuff, that is apparent. Thanks Patrick and Dr. Sohl for passing the word along. >_______________________________________________ >Utah-Astronomy mailing list >http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy > >Send messages to the list to >Utah-Astronomy(a)mailman.xmission.com > >The Utah-Astronomy mailing list is not affiliated with any astronomy club. > >To unsubscribe go to: >http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy >Then enter your email address in the space provided and click on "Unsubscribe or edit options".

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Making a 36" from many smaller mirrors
by Jay inUT 08 Sep '15

08 Sep '15

Ok, I got approached by my boss at work about the possibility of making a 36" mirror for observing from say several 8 inch mirrors (think an arrangement like James Webb). In thinking about this to me it seems that there are issues here about positioning the mirrors and ensuring that once ground, they form a parabola etc. So what are the thoughts on this? Can an amateur make a large mirror from smaller mirrors and what would it take? Just curious and I know what my reply was but I said I would inquire. -- Thanks! Jay

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Fw: Making a 36" from many smaller mirrors
by daniel turner 28 Aug '15

28 Aug '15

----- Forwarded Message ----- From: daniel turner <outwest112(a)yahoo.com> To: Siegfried Jachmann <siegfried(a)jachmann.org> Sent: Thursday, August 27, 2015 12:56 PM Subject: Re: [Utah-astronomy] Making a 36" from many smaller mirrors To make the Keck work they needed dozens of electric motors that would bend the cell to realign the mirrors every time the telescope was moved in elevation. It took a long time to develop and troubleshoot the computer system that controls all those motors and alignment sensors. This would be beyond the abilities of amateurs to perfect. Another way would be to build a mirror cell stiff enough to hold the mirrors in place against gravity. The best material to do this would be a giant piece of glass. Only glass is stiff enough and strong enough. Of course then you would be gluing your mirrors to a giant piece of glass. So why not just grind and figure the big piece of glass? DT From: Siegfried Jachmann <siegfried(a)jachmann.org> To: daniel turner <outwest112(a)yahoo.com>; Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Sent: Thursday, August 27, 2015 10:48 AM Subject: Re: [Utah-astronomy] Making a 36" from many smaller mirrors Yes but, the Keck telescopes are multiple mirror telescopes. Multiple mirror telescopes do work. Future space telescopes, including the James Webb and the proposed 12 meter, are designed to multiple mirror telescopes. It's not just the weight and sagging. It's the accuracy with which they must be aligned. Typically mirrors must be no worse that 1/4 wave from ideal. That also applies to multiple mirror scopes. SJ On Thu, Aug 27, 2015 at 9:36 AM, daniel turner via Utah-Astronomy <utah-astronomy(a)mailman.xmission.com> wrote: The figure of the mirror is held in place by the stiffness of the glass. With multiple mirrors you need a massive mirror cell or dynamic motors to constantly fight against the sag from gravity. In space it is easier because gravity is taken out of the equation. There was a professional telescope called the MMT which was arranged in a six gun fashion. But that was just to have something to do until the big onepiece of glass was ground, figured, and polished. So there is no real advantage in the long run. DT From: Jay inUT <jayleads(a)gmail.com> To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> Sent: Wednesday, August 26, 2015 6:58 PM Subject: [Utah-astronomy] Making a 36" from many smaller mirrors Ok, I got approached by my boss at work about the possibility of making a 36" mirror for observing from say several 8 inch mirrors (think an arrangement like James Webb). In thinking about this to me it seems that there are issues here about positioning the mirrors and ensuring that once ground, they form a parabola etc. So what are the thoughts on this? Can an amateur make a large mirror from smaller mirrors and what would it take? Just curious and I know what my reply was but I said I would inquire. -- Thanks! Jay _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy(a)mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy(a)mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options". -- Siegfried

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Neat sunspots today
by John M. Craig 25 Aug '15

25 Aug '15

Hi Folks, Last week a good set of prominences, today (and yesterday--sorry didn't get it posted) there's a couple of complex sunspot groups that are the main attractions. In Ha light, you can see that they're interacting with each other (yesterday, it looked like almost classic bar-magnet lines between the two groups: arched lines in the chromosphere plasma between the two groups). I also saw one of the groups throw off a couple of flares yesterday. I haven't tried looking in white light, but I imagine they'd be interesting that way also. John

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Pretty spectacular prominences today
by John M. Craig 24 Aug '15

24 Aug '15

Hi Folks, Although the smoke's pretty obvious here in N Utah, H-a light comes through with remarkable clarity. There's some pretty great prominences today. If you have the gear and the daylight time, enjoy! If you'd like to have a look through my scope (I'm in Orem), you can contact me off the list. Ciao, John

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NEO 2010 AL30 passage
by Brent Watson 22 Aug '15

22 Aug '15

Patrick, That is a very nice animation of thee passage of NEO 2010 AL30 you got on EPOD today. Congratulations! Brent

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Eclipse weather
by Wiggins Patrick 22 Aug '15

22 Aug '15

Yesterday (the 21st) marked two years until the 2017 total eclipse of the Sun. As I've done the past couple of years I downloaded a satellite image taken at the time of day when the eclipse will be happening and added it to the montage of my two previous years' shots. Here's the result: https://www.facebook.com/groups/SLAS.Talk/

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SLAS meeting info
by Chuck Hards 21 Aug '15

21 Aug '15

Somebody posted a link to a map to the free parking area at SLCC recently. Is that link still active, and can someone repost it? I looked on the SLAS website but didn't see it. Hope to see you there tonight, come hear Mike talk about his big scope!

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Re: [Utah-astronomy] Pretty spectacular prominences today
by Mark Shelton 21 Aug '15

21 Aug '15

Thank you Craig for the notice. The sun was spectacular from woodland. Very nice prominences. 3 great ones. Thanks again Mark Sent from my iPhone > On Aug 20, 2015, at 11:25 AM, John M. Craig <jmcraig(a)xmission.com> wrote: > > This message has no content.

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Smoke-Haze vs Star Party
by Bruce Hugo 20 Aug '15

20 Aug '15

Anyone tried observing through this smokey haze? Just curious if we'll be able to see anything this weekend at the star party(s). Especially with the moon providing illumination. Clear skies (seriously!)Bruce Hugo

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