Archive for August 16, 2021

08/16/2021 – Ephemeris – The first Artemis mission (maybe) – CAPSTONE

August 16, 2021 Comments off

This is Ephemeris for Monday, August 16th. Today the Sun will be up for 13 hours and 59 minutes, setting at 8:46, and it will rise tomorrow at 6:47. The Moon, 1 day past first quarter, will set at 1:13 tomorrow morning.

Tonight’s Moon is a great one to view with a small telescope. Speaking of the Moon, a company called Rocket Lab will be launching the first Artemis program mission, later this year, in preparation to land crews back on the Moon. They are launching a small CubeSat to orbit the Moon in a Near Rectilinear Halo Orbit which always faces the Earth and never goes behind the Moon. To test whether all the mathematical calculations for the orbit actually work in real life. The satellite is called CAPSTONE (another tortured NASA acronym*). It will be launched from New Zealand, Rocket Lab’s main launch site first into a polar orbit before heading to the lunar orbit, taking several months to get there.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

* Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment. Told ya. Cislunar space is a spherical volume of space centered on the Earth, whose radius is the Moon’s distance. Beyond that is interplanetary space.


Rocket Lab had been planning to launch the CAPSTONE satellite from Wallops Island, Virginia, but approval was taking too long, so they moved the launch to their New Zealand launch site instead.

NASA CAPSTONE pathfinder for gateway orbit

NASA CAPSTONE* pathfinder for gateway orbit is to be launched late this year by Rocket Lab to prove out the near rectilinear orbit for the Lunar Gateway.