Recent comments in /f/space

__Augustus_ OP t1_jdoth9y wrote

Returning after 3 years. It may not look like it but this is the same telescope from here (and same haircut, lol). Lots of improvements including bigger bearings, new focuser, new truss clamps, a motorized EQ platform for tracking. 14.7" f/2.9 Dobsonian with a quartz mirror made by Steve Dodds. I have since built a number of telescopes up to 24" but this is once again my largest scope and I am beginning work on a 25" f/2.6 along with a 32" f/2.6 and 37" f/3, which I am grinding the mirrors for. I also regularly set up my telescopes for public outreach events including literally on street corners, and I am teaching friends to grind mirrors and make telescopes both locally and over the Internet. This scope has been to dozens of star parties and outreach events and still remains my favorite and it keeps getting better the more I tweak it.

Other than DIY astronomy stuff, I have no background in science or engineering, and I suck at math. Building one of these is not hard and it's a great way to get an affordable, not to mention custom instrument.

As always, if you're interested in buying or making a telescope I recommend /r/atming and /r/telescopes along with TelescopicWatch.com. You can build or buy a good telescope for as little as $130. The Hadley 114mm telescope is a lovely 3D-printed instrument you can easily make yourself for $150 or less.

Photo taken at the annual Stars Over Sabino event in Tucson, AZ.

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DoctorProfessorTaco t1_jdornit wrote

I think you mean 64x the radius of the Earth, not 1/64 the radius.

The radius of the Earth is 6,378km, I don’t think you mean that a circle with the diameter of the lunar orbit is 1/64 of that, or about 100km.

Additionally, even if you mean 64x larger, it’s still not quite correct. The average diameter of the lunar orbit is 768,000km. 1/64 of that is 12,000km.

What you probably meant to say was the average radius of the lunar orbit is approximately equal to 64x the radius of Earth, or that the radius of Earth is about 1/64 the average radius of the lunar orbit.

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rocketsocks t1_jdoqzdo wrote

The DC-X was doing vertical landings in the '90s, Blue Origin has been doing vertical landings with their New Shepard since 2015. Yes, it's harder to do with a larger rocket but Rocket Lab is stacking the odds in their favor (by going for RTLS only, for example), and they have the benefit of watching SpaceX having done it.

When SpaceX began testing landings of the Falcon 9 they had a grand total of 7 successful orbital launches under their belt. Rocket Lab has done over 30 launches of the Electron and they have a tremendous amount of public knowledge to draw from. I wouldn't be at all surprised if they succeeded with landing on the first attempt.

Starship is a great design, but it's incredibly ambitious and will take a while to achieve maturity because of its complexity and ambition. Far too many people are riding the Starship hype train imagining that as soon as it achieves partial success with an actual launch they'll start launching commercial payloads a week later and retire the Falcon 9 the week after that.

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