Starship Asterisk*

by **alter-ego** » Sun Jul 29, 2018 4:20 am

Chris Peterson wrote: ↑Sat Jul 28, 2018 2:41 pm
alter-ego wrote: ↑Sat Jul 28, 2018 5:00 am No doubt the telescope is a critical element for determining the limiting resolution. However, atmospheric turbulence due to thermal gradients is a general problem all earth-based observers.
... For me, imaging is the thing. But again, all is not lost. Planets are bright, which means it's possible to make very short exposures- tens of milliseconds. And then, to pick through hundreds or thousands of images for those with good seeing, and stack them together mathematically to reduce the noise that goes with short exposures. Basically, to automate in the computer what sketchers are doing at the eyepiece.

Yeah, without question imaging is the way to go, especially now where cameras and analysis / composition software has skyrocketed in capability and yet inexpensive enough for most amateurs. There was a day when sketches were made in a hybrid way - from observing the best video still-frames (tens of millisecond exposures) on a monitor. Visual astronomy has it's place, but the best science has been and will be founded in quantitative imagery.

by **neufer** » Sun Jul 29, 2018 3:34 am

Click to play embedded YouTube video.

by **Chris Peterson** » Sat Jul 28, 2018 2:41 pm

alter-ego wrote: ↑Sat Jul 28, 2018 5:00 am No doubt the telescope is a critical element for determining the limiting resolution. However, atmospheric turbulence due to thermal gradients is a general problem all earth-based observers.

Where I live, the skies are among the darkest possible. Great for deep sky objects. But we're typically underneath the jet stream. Very bad for high resolution. And the planets are often fairly low, just adding to the problems. Much of the time my telescopic view of Mars resembles a burning oil derrick. There are moments of clarity, though, which is what skilled visual observers learn to pick out (and potentially sketch). I'm not very interested in visual astronomy, though. For me, imaging is the thing. But again, all is not lost. Planets are bright, which means it's possible to make very short exposures- tens of milliseconds. And then, to pick through hundreds or thousands of images for those with good seeing, and stack them together mathematically to reduce the noise that goes with short exposures. Basically, to automate in the computer what sketchers are doing at the eyepiece.
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: mars_action.gif (90.38 KiB) Viewed 2941 times

: mars_steady_sm.jpg (6.34 KiB) Viewed 2941 times

by **alter-ego** » Sat Jul 28, 2018 5:00 am

MarkBour wrote: ↑Sat Jul 28, 2018 4:12 am
alter-ego wrote: ↑Sat Jul 28, 2018 3:29 am ... a sketch I made of Mars during the Sep - Oct 1988 opposition time.
Nice work !
I wish I had a scope that could reveal that much detail.

No doubt the telescope is a critical element for determining the limiting resolution. However, atmospheric turbulence due to thermal gradients is a general problem all earth-based observers. Location and object altitude are very important factors, as well as type of telescope used (aperture diameter, closed v open OTA). I let the scope sit for hours before attempting serious observing. Also my sketches took 10's of minutes each waiting for those higher-altitude, good-seeing moments. You're probably aware that patience is very rewarding for seeing detail in both planetary and faint, extended objects. Capturing quickly transient details is a subjective process requiring many moments of good seeing to confirm features, and my sketches do have errors in the finer details because of the process.

One accomplishment I feel good about is seeing all the Messier objects with my 2.4" refractor, most of which I saw within 100 miles of Seattle. If you have a scope, you can set goals for yourself within your means and likely surprise yourself with what you have.

by **MarkBour** » Sat Jul 28, 2018 4:12 am

alter-ego wrote: ↑Sat Jul 28, 2018 3:29 am ... a sketch I made of Mars during the Sep - Oct 1988 opposition time.

Nice work !
I wish I had a scope that could reveal that much detail.

by **MarkBour** » Sat Jul 28, 2018 4:07 am

Chris Peterson wrote: ↑Fri Jul 27, 2018 11:16 pm
heehaw wrote: ↑Fri Jul 27, 2018 10:47 pm
Chris Peterson wrote: ↑Fri Jul 27, 2018 6:09 pm I would assume that colonies on Mars would use nuclear power for most of their energy,
Is there any evidence, yet, for any deposits of Uranium (or Thorium) on Mars? High-grade?
No. But I don't think they'll be making anything complex. It's all going to come from Earth for a very long time.

You might be right. Perhaps you should tell this guy:

In the Musk image for a Mars colony, I think I can see
a) lots of solar panels
b) a couple of lovely sunlight-capturing greenhouses

admittedly, these are initial sketches, but like I said,
dust storms will add to the challenges of this Utopian image.

by **alter-ego** » Sat Jul 28, 2018 3:29 am

I happen to remember a sketch I made of Mars during the Sep - Oct 1988 opposition time. I scanned the discolored, wrinkly paper (below). I used a 13" Dob, attempted to add some realism with reddish/orange-ish colors and some contrast. Mars' altitude was memorably high (40.5°) from my Redmond, Wa location, and also bright (-2.7). I thought these conditions might have been special and may be why I wanted to capture a sketch. Looking at the history and future of opposition altitudes (from Redmond) for opposition magnitudes as bright or brighter than -2.7, I discovered Sep 1988 was a very special time. Sep 1781 was the last time an opposition was so well positioned at 42° alt, while the next one will occur on Oct 2067, also at 42° alt.

: Sketch of Mars near opposition - 1988

by **neufer** » Sat Jul 28, 2018 2:46 am

mars_or_bust wrote: ↑Sat Jul 28, 2018 1:46 am
within a few years martian moon phobos will merge with the parent planet in a firey descent ending its period of orbital decay. within a few years. literally. not thousands or millions of years but within a few years. at any time a space rock may smack into phobos causing it to hasten its decaying orbit - there are signs that the upper atmosphere of mars is already acting on phobos reducing its orbital speed and accelerating its descent through friction. gravity appears to be causing stress lines to appear on phobos exterior.

https://en.wikipedia.org/wiki/Phobos_(moon)#Predicted_destruction wrote:
<<Tidal deceleration is gradually decreasing the orbital radius of Phobos by 2 meters every one hundred years. Scientists estimate that Phobos will be destroyed in approximately 30–50 million years, with one study's estimate being about 43 million years.

Researchers suggest that the grooves are "stretch marks" caused by tidal forces. This idea is based on the model that Phobos is a rubble pile surrounded by a 100 m layer of powdery regolith. Stress fractures calculated for this model line up with the grooves on Phobos. The model is supported with the discovery that some of the grooves are younger than others, implying that the process that produces the grooves is ongoing. Given Phobos's irregular shape and assuming that it is a pile of rubble (specifically a Mohr–Cowbell Mohr–Coulomb body), it will eventually break up when it reaches approximately 2.1 Mars radii [from it's current 2.76 Mars radii orbit]

When Phobos is eventually torn apart by tidal forces, a fraction of the debris will likely form a planetary ring around Mars, which may last from one million to one hundred million years.>>

by **mars_or_bust** » Sat Jul 28, 2018 1:46 am

vicinity of the terestrial planets is more crowded with asteroids and rocky debris than previously thought. every month thousands of tons of dust and cosmic rock must pelt the atmospheres of the terestrial planets delivering molecules of silicates and water and noble gas and metallic crystal. the earth is certainly a collection bin for cosmic material day and night. the moon seems to support a very tenuous atmosphere. mars and venus must be well supplied with star dust.

within a few years martian moon phobos will merge with the parent planet in a firey descent ending its period of orbital decay. within a few years. literally. not thousands or millions of years but within a few years. at any time a space rock may smack into phobos causing it to hasten its decaying orbit - there are signs that the upper atmosphere of mars is already acting on phobos reducing its orbital speed and accelerating its descent through friction. gravity appears to be causing stress lines to appear on phobos exterior.

the merge of phobos with mars will increase the mass of the planet substantially. thousands of tons of water frozen in phobos interior wil be released into martian atmosphere. perhaps phobos is a captured asteroid - perhaps this the way things work here. the merge of phobos with mars will mark a new period in solar system history.

by **heehaw** » Sat Jul 28, 2018 12:42 am

Boomer12k wrote: ↑Fri Jul 27, 2018 11:42 pm Without the dust storm, it would probably be my best image...however....

I remember when as a kid in Ottawa about 1950 my parents took me to the observatory and I saw a wobbly image of Mars, much like your nice photo. That made a deep impression on me!

by **Boomer12k** » Fri Jul 27, 2018 11:42 pm

I have gotten a couple of shots myself, not that there is that much to see...took the image a few night ago with my Celestron Evolution 6". You can see a bit of faint detail.

Without the dust storm, it would probably be my best image...however....

Hope it ends soon, but I think they can last awhile.

:---[===] *

by **Chris Peterson** » Fri Jul 27, 2018 11:16 pm

heehaw wrote: ↑Fri Jul 27, 2018 10:47 pm
Chris Peterson wrote: ↑Fri Jul 27, 2018 6:09 pm I would assume that colonies on Mars would use nuclear power for most of their energy,
Is there any evidence, yet, for any deposits of Uranium (or Thorium) on Mars? High-grade?

No. But I don't think they'll be making anything complex. It's all going to come from Earth for a very long time.

by **heehaw** » Fri Jul 27, 2018 10:47 pm

Chris Peterson wrote: ↑Fri Jul 27, 2018 6:09 pm I would assume that colonies on Mars would use nuclear power for most of their energy,

Is there any evidence, yet, for any deposits of Uranium (or Thorium) on Mars? High-grade?

by **Chris Peterson** » Fri Jul 27, 2018 7:44 pm

MarkBour wrote: ↑Fri Jul 27, 2018 7:39 pm
Chris Peterson wrote: ↑Fri Jul 27, 2018 6:09 pm
MarkBour wrote: ↑Fri Jul 27, 2018 3:29 pm Imagine how disruptive such a global dust event would be here on Earth.

Imagine how hard it would be for space colonists to deal with; one more huge challenge to overcome.
I don't imagine such a storm being very disruptive on Mars at all, except for solar powered installations.
Mostly what I was thinking of was solar power and agriculture. But what other power sources will people use on a Mars colony? And don't they essentially shut down the rovers when they are in a dust storm? But people can't shut down their energy usage for 6 months in such a hostile environment as Mars. That's why I think it is a big challenge.

I would assume that colonies on Mars would use nuclear power for most of their energy, and that agriculture would be largely hydroponic with controlled lighting. So in practice, I think people would operate almost exactly the same whether or not there was any dust storm in progress. It certainly wouldn't block enough light to be a problem for people doing tasks outside.

by **MarkBour** » Fri Jul 27, 2018 7:39 pm

Chris Peterson wrote: ↑Fri Jul 27, 2018 6:09 pm
MarkBour wrote: ↑Fri Jul 27, 2018 3:29 pm Imagine how disruptive such a global dust event would be here on Earth.

Imagine how hard it would be for space colonists to deal with; one more huge challenge to overcome.
I don't imagine such a storm being very disruptive on Mars at all, except for solar powered installations.

Mostly what I was thinking of was solar power and agriculture. But what other power sources will people use on a Mars colony? And don't they essentially shut down the rovers when they are in a dust storm? But people can't shut down their energy usage for 6 months in such a hostile environment as Mars. That's why I think it is a big challenge.

by **Chris Peterson** » Fri Jul 27, 2018 6:09 pm

MarkBour wrote: ↑Fri Jul 27, 2018 3:29 pm Imagine how disruptive such a global dust event would be here on Earth.

Imagine how hard it would be for space colonists to deal with; one more huge challenge to overcome.

I don't imagine such a storm being very disruptive on Mars at all, except for solar powered installations.

by **MarkBour** » Fri Jul 27, 2018 3:29 pm

Imagine how disruptive such a global dust event would be here on Earth.

Imagine how hard it would be for space colonists to deal with; one more huge challenge to overcome.

by **bystander** » Fri Jul 27, 2018 1:32 pm

heehaw wrote: ↑Fri Jul 27, 2018 10:58 am Did you see that they've found a ... 12-mile-wide body of water on Mars? Lake Superior!

viewtopic.php?t=38548

by **heehaw** » Fri Jul 27, 2018 10:58 am

Did you see that they've found a ... 12-mile-wide body of water on Mars? Lake Superior!

by **APOD Robot** » Fri Jul 27, 2018 4:07 am

Mars Opposition

Explanation: Look opposite the Sun in the sky tonight and you'll see Mars at its brightest. Also within days of its closest approach Mars rises at sunset, near its brightest and best for telescopic observers too, except for the dust storm still blanketing the Red Planet. These two Hubble Space Telescope images compare Mars' appearance near its 2016 and 2018 oppositions. In 2016 the martian atmosphere was clear. Captured just days ago, the 2018 image shows almost the same face of Mars. Surface features obscured by dust, the planet's cloud enshrouded south pole is tilted more toward the Sun. Increased heat in the southern hemisphere spring and summer likely triggers planet wide dust storms. Of course, if you look opposite the Sun in the sky tonight, you'll also see a Full Moon near Mars. Skygazers NOT located in North America could see the Red Planet near a Red Moon during a Total Lunar Eclipse.

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