The Orbital Mechanics Podcast

This week in SF history

— January 31, 1961: Mercury MR-2 (wikipedia.org)

Spaceflight news

— Starship Hopper's nose cone knocked over by heavy winds. (brownsvilleherald.com)

Short & Sweet

— Commercial crew swaps an astronaut. (spacenews.com)

— Blue Origin is coming to Alabama. (spacenews.com)

— Hubble’s primary camera is back online.
(spaceflightnow.com)

Questions, comments, corrections

— By-line mixup, Chris Bush vs Ben McPheron

Data Relay: Spacecraft Navigation

— Thanks to Ben McPheron for researching and presenting this topic

— twitter.com/bdmcpheron

— benjaminmcpheron.com

— youtube.com/DMExplains

— Three interrelated systems: Guidance, Navigation and Control (GNC) (wikipedia.org)

— Onboard sensors

— Even high quality sensors drift (PDF: orbit.dtu.dk) (youtube.com)

—Inertial sensors (IEEE)

— Gyroscopes (PDF: orbit.dtu.dk)

— Hubble used gas bearings (spacetelescope.org)

— Optical gyroscope (PDF: orbit.dtu.dk) (wikipedia.org) (PDF: nasa.gov)

— First optical gyroscope in space was the Rossi X-Ray timing Explorer spacecraft, launched in 1995 (PDF: nasa.gov)

— Sagnac Effect (youtube.com)

— Inertial measurement Units (wikipedia.org) (nasa.gov)

— Magnetometers measure the size and orientation of the magnetic field (PDF: orbit.dtu.dk)

— Eight different types in one particular source (engineersgarage.com)

— Orbital models (PDF: orbit.dtu.dk)

— Non inertial sensors for determining attitude

— Sun sensors (PDF: orbit.dtu.dk) (wikipedia.org)

— Solar Panels (youtube.com)

— Star Trackers/Star imagers (nasa.gov) (PDF: orbit.dtu.dk) (science.gov)

— Update rate on star trackers are generally 1-10 Hz, but can be up to 100 Hz at max (PDF: OSApublishing.org)

— Hubble’s Fine Guidance System (HubbleSite.org)

— Apollo ‘Person In Loop’ Star Tracking (NASA.gov) (Astronomy.com) (youtube.com)

— Lovell had to work hard due to the field of debris around his vehicle (wikipedia.org)

— Shuttle had one too, located forward and left of commander’s window (NASA.gov)

— RADAR/LIDAR (NASA.gov)

— Used in Apollo, specifically for lunar landing (NASA.gov)

— Offboard sensors

— RF beacons can be used as reference (PDF: orbit.dtu.dk) (wikipedia.org)

— DSN Precise One Way Metric Tracking (PDF: jpl.nasa.gov)

— Single-sample accuracy up to 0.05 mm/s and 3 m (scientificamerican.com) (PDF: researchgate.net)

— NASA would like to update this to use laser communications (PDF: nasa.gov)

— JPL leading development of a deep space atomic clock to further improve this system (jpl.nasa.gov)

Future technologies

— X-ray pulsar navigation

— Developed at NASA Goddard (PDF: nasa.gov)

— Closely analogous to GPS tracking (nasa.gov)

— Make use of a large number of extremely stable millisecond pulsars (howstuffworks.com, nasa.gov)

— SEXTANT experiment on ISS (nasa.gov)