Category: Space Exploration

  • Triple EVA

    John F. Lindner

    Since the mid 1960s, all space walks or extra-vehicular activities (EVAs) have involved just one or two astronauts — except once. In May 1992, on the STS-49 mission, the crew of the space shuttle Endeavour was attempting to rescue a stranded communications satellite, Intelsat 603. After repeated two-person EVAs failed to capture the satellite, NASA and the…

  • Artemis Is the Sister of Apollo

    John F. Lindner

    I stayed up late last night and early this morning to watch the successful uncrewed launch of Artemis 1. In Greek tradition, Artemis was the twin sister of Apollo, and the Artemis program hopes to return humans — including the first woman — to Moon as preparation for sending them onward to Mars. As a child…

  • Zero-G Indicator

    John F. Lindner

    When Crew 5 rocketed to orbit last week aboard the SpaceX Dragon “Endurance” bound for the International Space Station, I was curious to see their zero-gravity indicator. A tradition SpaceX crews have adopted from Russian cosmonauts, the zero-g indicator is usually a stuffed animal whose first float announces the free-fall of Earth orbit. Was that a plush Einstein doll?…

  • For the dinosaurs!

    John F. Lindner

    The dinosaurs didn’t have a space program, but we do. I just watched live the first kinetic-impact asteroid-redirection test as NASA’s Double Asteroid Redirection Test spacecraft collided with the asteroid-moon Dimorphos of the asteroid Didymos. Below is the last image DART transmitted, truncated by the impact itself! The goal is to measurably change the speed…

  • GRAVITY and Gravity

    John F. Lindner

    In Alfonso Cuarón‘s Oscar-winning 2013 movie GRAVITY, actress Sandra Bullock‘s Dr. Ryan Stone makes an emergency entrance into an abruptly abandoned International Space Station. This month, European Space Agency astronaut Samantha Cristoforetti recreated this scene onboard the space station, as in the photograph below, with the movie playing on the ISS Viewscreen. In GRAVITY, “gravity” refers…

  • Diffraction Limited

    John F. Lindner

    Yesterday, Webb optical telescope element manager Lee Feinberg said “We made the right telescope” while reporting that its focus has reached the  diffraction limit of 0.7 arcseconds at the infrared wavelength of 2 microns. (For comparison, from Earth, Luna subtends 31 arcminutes, which is about 1/2°.) Unlike the Hubble space telescope, whose primary mirror was…

  • Halo Orbit

    John F. Lindner

    The Webb telescope has fully deployed and arrived at its halo orbit about the second Earth-Sun Lagrange point. But how can it orbit an empty point in space? In the accompanying animated sequence of inertial space diagrams, a star (red) and planet (cyan) orbit their common center of mass (cross). The inward force to pull…

  • Merlin & Raptor

    John F. Lindner

    The turbopump is the heart of most liquid-fueled rocket engines. Gas generator engines tap off and burn a little propellant to drive a turbine, which turns a centrifugal pump, which rapidly pushes the fuel and oxidizer to the combustion chamber, after the cryogenic fuel first circulates around the rocket nozzle to cool it. The combustion generates supersonic exhaust out…

  • Astronomy Christmas Gift

    John F. Lindner

    I awoke early this Christmas morning to watch the successful launch of the James Webb Space Telescope. I remember the genesis of the telescope a quarter of a century ago when it was called the Next Generation Space Telescope. (The telescope’s name is controversial, and I would have preferred an astronomer’s name.) Its development has…

  • Part Science, Part Art, Part Luck

    John F. Lindner

    Launched just last month, Lucy will be the first spacecraft to visit Jupiter’s trojan asteroids, rocky swarms that orbit about 60 degrees ahead and behind Jupiter in its orbit. Hal Levison, Lucy’s Principal Investigator, has described Lucy’s complicated trajectory, which includes an Earth gravity-assist and visits to both trojan swarms, as “part science, part art, and part luck”.…

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