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Fram2 Over the Poles
Historically, astronauts have launched roughly east to exploit Earth’s spin, as the terrestrial equator moves at nearly 1000 mph with respect to its center. But last week the Fram2 SpaceX Dragon crew launched south from the Kennedy Space Center to become the first humans to orbit Earth over its poles. The all-private, all-international, rookie crew…
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2D Kepler Conjecture
Johannes Kepler asserted in 1611 that no packing of identical balls has density greater than the hexagonal close-packed “cannonball” packing of oranges at a grocery store’s fruit stand. But the gulf between intuition and proof was so large that the latter was not achieved until the work of Thomas Hales and Samuel Ferguson in 1998.…
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Blue Ghost Eclipse
Last night’s lunar eclipse, as seen from Earth, looked like a solar eclipse, as seen from Luna. Firefly Aerospace‘s NASA-funded Blue Ghost lunar lander recently became the first commercial spacecraft to successfully land on Earth’s moon Luna. Blue Ghost’s mission is designed to last a single lunar day, about two terrestrial weeks. Last night it…
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Mach Cutoff
Two weeks ago, I watched live via Starlink as the Boom Supersonic XB-1 test aircraft broke the sound barrier in level flight, the first all-civilian aircraft to do so. This success promises the return of commercial supersonic flight, at least over ocean. This week, during the final test flight, I learned that no sonic boom…
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Mount Wilson Trek
Nobody walks in L.A., but as a Caltech grad student without a car in the mid 1980s, I once walked from my dorm room up Mount Wilson and touched the enclosure of the famous 100-inch (2.54-meter) Hooker telescope, for 32 years, the world’s largest, where Hubble discovered that the Andromeda “nebula” was actually a galaxy…
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Outer Planet Cloud Colors
From my teens to my twenties, from junior high school to graduate school to young professor, I excitingly followed the first reconnaissance of the outer solar system by the Pioneer and Voyager spacecraft. But the exploration isn’t over. For the last decade, the Hubble Space Telescope has been systematically observing the colors and dynamics of…
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Sum of Reciprocals
The sum of the reciprocals of the natural numbers diverges, but slowly, like the logarithm of the number of terms. The sum of the reciprocals of the prime numbers also diverges, but even more slowly, like the logarithm of the logarithm of the number of terms, as the primes are sparse in the naturals! Here…
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There and Back Again
I awoke yesterday at dawn in a log cabin in Vermont. Fortunately, the wifi was good. Each successive test of the SpaceX Superheavy Starship has been a significant improvement over the previous one, and test five was no exception, with both the booster and the ship demonstrating soft pinpoint landings — except this time, the…
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Rey’s Theme
Yesterday, as part of the Polaris Dawn mission, SpaceX engineer Sarah Gillis became the youngest person to walk in space. Today, on a space-qualified violin, she performed Rey’s Theme, composed by John Williams as the musical leitmotif for Rey, the central character in the Star Wars movie The Force Awakens. The performance audio and video…
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Skywalker
Up before dawn this morning for the Polaris Dawn space walk, the first commercial space walk and the furthest from Earth since the Apollo program over half a century ago. After stalling for so long, human space flight is again advancing. Polaris Dawn’s Commander Jared Isaacman, Pilot Scott “Kidd” Poteet, Mission Specialist Sarah Gillis, and…
Author: John F. Lindner
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Nice post, John! Thanks for writing these. I always enjoy them.
David Smith’s ein stein is an awesome shape!
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Thanks, Mark! I enjoy reading your posts as well.