The Great Moon Hoax — No Not That One!

July 23, 2019 by Al Williams 64 Comments

Humans first walked on the moon 50 years ago, yet there are some people who don’t think it happened. This story is not about them. It turns out there was another great conspiracy theory involving a well-known astronomer, unicorns, and humanoids with bat wings. This one came 134 years before the words “We chose to go to the moon” were uttered.

The 1835 affair — known as the Great Moon Hoax — took the form of six articles published in The Sun, a newspaper in New York City. Think of it like “War of the Worlds” but in newspaper form — reported as if true but completely made up. Although well-known astronomer John Herschel was named in the story, he wasn’t actually involved in the hoax. Richard Adams Locke was the reporter who invented the story. His main goal seemed to be to sell newspapers, but he also may have been poking fun at some of the more outlandish scientific claims of the day.

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Reverse Engineering Keeps Keck Telescopes On Track

February 26, 2019 by Dan Maloney 13 Comments

Perched atop a dormant volcano far above the roiling tropical air of the Big Island of Hawai’i sit two of the largest optical telescopes in the world. Each 10-meter main mirror is but a single part of a magnificent machine weighing in at some 400 tons that needs to be positioned with incredible precision. Keeping Keck 1 and Keck 2 in peak operating condition is the job of a team of engineers and scientists, so when the servo amplifiers running the twelve motors that move each scope started to show their age, [Andrew] bit the bullet and rebuilt the obsolete boards from scratch.

The Keck telescopes were built over three decades ago, and many of the parts, including the problematic servo amps, are no longer made. Accumulated wear and tear from constant use and repeated repairs had taken their toll on the boards, from overheated components to lifted solder pads. With only some barely legible schematics of the original amplifiers to go by, [Andrew] reverse engineered new amps. Some substitutions for obsolete components were needed, the PCB design was updated to support SMD parts, and higher-quality components were specified, but the end result is essentially new amplifiers that are plug-in replacements for the original units. This should keep the telescopes on track for decades to come.

Not to sound jealous, but it seems like [Andrew] has a great gig. He’s shared a couple of his Keck adventures before, like the time a failed LED blinded the telescope. He’s also had a few more down-to-earth hacks, like fixing a dodgy LCD monitor and making spooky blinkeneyes for Halloween.

DIY Guided Telescope Mount Tracks Like A Barn Door

January 12, 2019 by Ted Yapo 8 Comments

Astrophotography is an expensive hobby. When assembling even a basic setup consisting of a telescope, camera, guiding equipment and mount, you can easily end up with several thousand dollars worth of gear. To reduce the monetary sting a little, [td0g] has come up with an innovative homebrew mount and guiding solution that could be assembled by almost any dedicated amateur, with the parts cost estimated around $100. The accuracy required to obtain high-quality astrophotographs is quite demanding, so we’re impressed with what he’s been able to achieve on a limited budget.

The inspiration for this design comes from an incredibly simple star tracking device known as a barn-door tracker, or Haig mount. Invented by George Haig in the 1970’s, this mount is essentially nothing more than a hinge aligned with the Earth’s axis of rotation. A threaded rod or screw, turned at a constant rate, is used to slowly open the hinge so that a mounted camera tracks the apparent motion of the heavens. As a result, long exposures can show pinpoint images of stars and sharp details of deep-sky objects, instead of curved star trails. [td0g] adapted this technique to drive a more traditional telescope mount, using barn-door-like drive screws on both the right ascension and declination axes. A pair of NEMA 17 stepper motors drive 4-mm pitch Acme threaded rods through toothed pulleys 3D printed from PETG.

Speaking of 3D-printed parts, this build is a good example of judicious use of the technology: where metal parts are warranted, metal parts are used, and printed plastic is relegated to those places where it can adequately do the job. [td0g] has placed the STL files for the printed parts on Thingiverse in case you want to replicate the drive.

The non-linear relationship between the threaded rod rotation and right ascension drive rate usually limits the length of exposure you can reasonably achieve with a barn-door tracker. To adjust for this, [td0g] created a lookup table in firmware to compensate the drive and allow longer exposures. He mentions that the drive will operate for three hours before it hits the end of the screw’s travel and needs to be reset, but if he can manage three hour exposures, his skies must be much darker than ours!

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Pi Zero Gives Amateur Astronomer Affordable Control Of Telescope

January 3, 2019 by Dan Maloney 18 Comments

Like many other hobbies, astronomy can be pursued on many levels, with equipment costs ranging from the affordable to the – well, astronomical. Thankfully, there are lots of entry-level telescopes on the market, some that even come with mounts that automatically find and track heavenly bodies. Finding a feature is as easy as aligning to a few known stars and looking up the object in the database embedded in the remote.

Few of the affordable mounts are WiFi-accessible, though, which is a gap [Dane Gardner]’s Raspberry Pi interface for Celestron telescopes aims to fill. For the price of a $10 Pi Zero W and a little know-how, [Dane] was able to gain full control over his ‘scope. His instrument is a Celestron NexStar, a Schmidt-Cassegrain reflector with a 150-mm aperture, has a motorized altitude-azimuth mount. The handheld remote had enough room for him to add the Zero, powering it from the mount’s battery pack. The handset has an RS-232 serial port built-in, but with the level differences [Dane] just connected the Pi directly to the handset before the UART. Running INDI, a cross-platform astronomical instrument control library, he now has total control of the scope, and he can use open source astronomy software rather than the limited database within the handset. As a neat side trick, the telescope can now be controlled with a Bluetooth gamepad.

Astronomy and electronics go hand in hand, whether in the optical or radio part of the spectrum. We like the way [Dane] was able to gain control of his telescope, and we’d like to hear about what he sees with his new tool. Assuming the Seattle weather ever cooperates.

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Flagging Down Aliens With World’s Biggest Laser Pointer

November 20, 2018 by Tom Nardi 86 Comments

As you’re no doubt aware, humans are a rather noisy species. Not just audibly, like in the case of somebody talking loudly when you’re in a movie theater, but also electromagnetically. All of our wireless transmissions since Marconi made his first spark gap broadcast in 1895 have radiated out into space, and anyone who’s got a sensitive enough ear pointed into our little corner of the Milky Way should have no trouble hearing us. Even if these extraterrestrial eavesdroppers wouldn’t be able to understand the content of our transmissions, the sheer volume of them would be enough to indicate that whatever is making all that noise on the third rock orbiting Sol can’t be a natural phenomena. In other words, one of the best ways to find intelligent life in the galaxy may just be to sit around and wait for them to hear us.

Of course, there’s some pesky physics involved that makes it a bit more complicated. Signals radiate from the Earth at the speed of light, which is like a brisk walk in interstellar terms. Depending on where these hypothetical listeners are located, the delay between when we broadcast something and when they receive it can be immense. For example, any intelligent beings that might be listening in on us from the closest known star, Proxima Centauri, are only just now being utterly disappointed by the finale for “How I Met Your Mother“. Comparatively, “Dallas” fans from Zeta Reticuli are still on the edge of their seats waiting to find out who shot J.R.

But rather than relying on our normal broadcasts to do the talking for us, a recent paper in The Astrophysical Journal makes the case that we should go one better. Written by James R. Clark and Kerri Cahoy, “Optical Detection of Lasers with Near-term Technology at Interstellar Distances” makes the case that we could use current or near-term laser technology to broadcast a highly directional beacon to potentially life-harboring star systems. What’s more, it even theorizes it would be possible to establish direct communications with an alien intelligence simply by modulating the beam.

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DIY laser rifle doing damage long distance

DIY Long Distance Laser Telescope Does Some Damage

August 31, 2018 by Steven Dufresne 44 Comments

Here’s a DIY laser rifle which can explode a balloon at around 150 feet (45 meters) as well as some angry chemicals at a similar distance. Since there are plenty of videos of lasers doing that at around a meter, why shouldn’t doing so farther away be easy? Despite what many expect, laser beams don’t remain as straight lines forever. All light diverges over a distance. This makes it hard to create a laser which can do damage from more than around a meter and is why most demonstrations on YouTube are that distance or less.

[Styropyro’s] handheld, DIY laser rifle, or Laser Telescope Blaster as he calls it, works for long distances. His solution lies in some surprising physics: the larger the diameter of the beam, the more slowly it will diverge. So he used the opposite of a Galilean telescope to take the small beam of his 405-nanometer laser and increase its diameter. His best result was to explode a balloon at 150 feet (45 meters).

He did run into another issue first though. Anyone who’s tried to keep a camera aimed at a target through a telephoto lens while holding the camera in their hands knows that even a tiny movement will throw the camera off target. For a laser beam to sufficiently heat up the balloon in order to make it explode, the beam has to stay on it for a short period of time. But at a long distance, small movements of his rifle made the beam wander. Putting the rifle on a tripod fixed that. In the video below you can see him work through his design and these issues to finally get his big success.

We can guess what spurred on this interest in long-distance laser rifles. Back in July, a Chinese company made bold claims to building one which could do damage at 800 meters.

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Catch A Rising Star With Arduino

April 26, 2018 by Al Williams 10 Comments

Space is big. Really big. Yet on TV and movies, enemy spacecraft routinely wind up meeting at roughly the same spot and, miraculously, in the same orientation. If you’ve ever tried to find something smaller than the moon in a telescope, you’ll appreciate that it isn’t that easy. There are plenty of tricks for locating objects ranging from expensive computerized scopes with motors to mounting a phone with Google Sky or a similar program to your telescope. [DentDentArthurDent] didn’t use a phone. He used an Arduino with an outboard GPS module.

You still have to move the scope yourself, but the GPS means you know your location and the time to a high degree of accuracy. Before you start an observing session, you simply point the telescope at Polaris to calibrate the algorithm, a process which in the northern hemisphere is pretty easy.

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