On This Day in 1973, Skylab Launched

NASA // Public Domain
NASA // Public Domain

On May 14, 1973 NASA launched Skylab, the first American space station. It fell to earth six years later, burning up in 1979.

Skylab itself was a heavily modified third stage of a Saturn V rocket—the same system we used to send Apollo missions to the moon. The station was huge, measuring more than 80 feet long, with a 21-foot diameter. During launch, Skylab 1 suffered major damage to its solar array, which delayed launch of the Skylab 2 crew (originally intended to launch the day after Skylab itself reached orbit). The Skylab 2 mission was modified to include repair work to the solar power system and installation of a solar heat shield, as the original one was lost during launch. The Skylab 2 crew launched on May 25, 1973.

The Skylab missions resulted in new information about long-term space habitation (including an awesome space shower). The first crew spent 28 days in space; the second 59 days; and the last crew (Skylab 4) spent 84 days up there. That last record was not broken by an American for two decades. Skylab also focused on solar science, earth science, and microgravity experiments.

Skylab was something of a bridge between the Apollo and Space Shuttle programs. Indeed, Skylab was supposed to be serviced (and its orbit boosted) by the first Shuttle, but it wasn't ready in time. Skylab's orbit decayed, eventually causing it to disintegrate and fall to Earth in 1979. Chunks of the station made a bit of a fireworks display streaking through the atmosphere, and ultimately littered a swath of Australia. No injuries were reported from the falling debris, though media coverage of the re-entry was intense.

Here's a half-hour NASA documentary on Skylab, explaining the story of the station and focusing on the science conducted in orbit. Have a look:

If you'd like to relive the launch, here's live TV coverage from that day.

Lítla Dímun: The Smallest of the Faroe Islands Has Its Very Own Cloud

While some islands are known for their unusual geography or unique history, Lítla Dímun is notable for its weather. The island, which is the smallest of Denmark's Faroe Islands chain, is often capped by a lens-shaped cloud, making it resemble a scene from a fairytale.

According to Mental Floss's own Kerry Wolfe writing for Atlas Obscura, the cloud floating above Lítla Dímun is a lenticular cloud. This type of cloud forms when moist air flows over a protruding geological feature, like a mountain top. When the wind moving up the landmass hits the air current directly above it, a sort of wave is created on the downwind side of the mountain. The moist air falling down this wave evaporates and then condenses into a large, flying-saucer-shaped cloud atop the mountain peak as a result.

Another factor that makes Lítla Dímun distinct is that it's the only one of the 18 main Faroe Islands without human inhabitants. Visitors to the mystical location will instead find a thriving population of sheep. Originally, Lítla Dímun was home to a group of feral sheep likely dating back to the Neolithic era. But they were hunted to extinction in the 19th century. Domesticated sheep were introduced there around the same time, and today, farmers visit the island once a year to round up their flocks.

One of the few signs of human life are the ropes farmers use to scale the cliff faces bordering the island. Even if you have rock-climbing skills, Lítla Dímun may be dangerous to visit. A boat ride to the rocky shore is only possible when the surrounding sea is calm.

[h/t Atlas Obscura]

Why Are Sloths So Slow?

Sloths have little problem holding still for nature photographers.
Sloths have little problem holding still for nature photographers.
Geoview/iStock via Getty Images

When it comes to physical activity, few animals have as maligned a reputation as the sloth. The six sloth species, which call Brazil and Panama home, move with no urgency, having seemingly adapted to an existence that allows for a life lived in slow motion. But what makes sloths so sedate? And what horrible, poop-related price must they pay in order to maintain life in the slow lane?

According to HowStuffWorks, the sloth’s limited movements are primarily the result of their diet. Residing mainly in the canopy vines of Central and South American forests, sloths dine out on leaves, fruits, and buds. With virtually no fat or protein, sloths conserve energy by taking a leisurely approach to life. On average, a sloth will climb or travel roughly 125 feet per day. On land, it takes them roughly one minute to move just one foot.

A sloth’s digestive system matches their locomotion. After munching leaves using their lips—they have no incisors—it can take up to a month for their meals to be fully digested. And a sloth's metabolic rate is 40 to 45 percent slower than most mammals' to help compensate for their low caloric intake. With so little fuel to burn, a sloth makes the most of it.

Deliberate movement shouldn’t be confused for weakness, however. Sloths can hang from branches for hours, showing off some impressive stamina. And because they spend most of their time high up in trees, they have no need for rapid movement to evade predators.

There is, however, one major downside to the sloth's leisurely lifestyle. Owing to their meager diet, they typically only have to poop once per week. Like going in a public bathroom, this can be a stressful event, as it means going to the ground and risking detection by predators—which puts their lives on the line. Worse, that slow bowel motility means they’re trying to push out nearly one-third of their body weight in feces at a time. It's something to consider the next time you feel envious of their chill lifestyle.

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