Author Archives: John F. Lindner

Historically, astronauts have launched roughly eastward to exploit Earth’s spin, whose equator moves at nearly 1000 mph with respect to its center. But last week the Fram2 SpaceX Dragon crew became the first humans to orbit Earth over its poles. … Continue reading →

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 … Continue reading →

Last night’s lunar eclipse, as seen from Earth, looked like a solar eclipse, as seen from Moon. Firefly Aerospace‘s NASA-funded Blue Ghost lunar lander recently became the first commercial spacecraft to successfully land on Moon. Blue Ghost&#8217… Continue reading →

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 … C… Continue reading →

Nobody walks in L.A., but as a Caltech grad student in the mid 1980s without a car, I once walked from my dorm room up Mount Wilson and touched the enclosure of the famous 100-inch Hooker telescope where Hubble & … Continue reading → Continue reading →

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 &… Continue reading →

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 … Continue reading &… Continue reading →

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 … Continue … Continue reading →

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, t… Continue reading →

Up before dawn this morning to watch 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 … Continue reading &… Continue reading →