Artemis: From Gateway to Low Lunar Orbit

One concept Gateway may be in a polar orbit with an apolune of 70,000 km and perilune of 3,000 km. One concept is for the lander and Orion to meet at Gateway. Our alternative is for Artemis to stay in a low lunar orbit and be met there by Orion, the cargo transfer vehicle and the tanker. There are many orbit maneuver sequences that will get us from Gateway to our 15 km altitude orbit. A simple one is shown below. We first lower apogee to 3,000 km we then do a Hohmann transfer from the 3,000 km orbit to the 1753 km orbit (that is 15 km altitude). The maneuver to lower apogee is shown below.

The delta-v for the first maneuver is 0.49 km/s and for the Hohmann transfer is 0.39 km/s.

While in low lunar orbit in between landings the lunar lander will do high resolution photo surveys of the surface. These will be used to train the neural network for landing navigation.

Artemis: NASA RFP for Lunar Landers

NASA recently released a request for proposal for a lunar lander with a due date of November 1.

https://www.nasa.gov/feature/fast-track-to-the-moon-nasa-opens-call-for-artemis-lunar-landers

NASA would like a crew to land on the moon by 2024.

We didn’t have time to write a proposal, but here is our design. We propose a single stage vehicle, that can land from and return to a 15 km circular orbit. It uses 2 Blue Origins BE-3U engines that use cryogenic hydrogen and oxygen. An Orion capsule houses the astronauts. The Orion would take astronauts to and from Gateway and to and from the Earth. Lockheed Martin is building the Orion spacecraft. The European Space Agency is building the service module. A separate transport would bring fuel and payload to the lander. In the future, the lander could be refueled from lunar water.

The dimensions are in meters. The Orion is shown below. We purchased the model from https://hum3d.com.

The landing gear were scaled from the Apollo Lunar module.

It is interesting to compare its size with the Apollo Lunar Module. The Artemis is designed to fit into the 10 m SLS fairing. This a fully reusable lunar vehicle that can be refueled. It is designed for a long-term, sustainable, lunar base.

We use two toroidal hydrogen tanks and two spherical oxygen tanks. The cylinder on the outside is the solar array producing 34 kW of power. Of course, numerous details are omitted. We developed this model using our Spacecraft Control Toolbox. The design script will be available in the Spacecraft Control Toolbox Version 2019.1 due in mid-November.

Other elements of the lander were designed for different purposes. The GN&C system is based on our Army Precision Attitude Control System.

Our control system is based on a robotic lander we designed some time ago. We have full C++ code for the control and guidance system.

The architecture for Earth/Moon transportation system is shown below. Eventually, a Direct Fusion Drive freighter would be the main way of moving cargo between Earth orbit, lunar orbit and Gateway. The lander would remain in lunar orbit. Humans would go to the moon using fast orbital transfer, much like during Apollo.

Our next blog post will show how we get from Gateway to and from our 15 km starting orbit. A subsequent post will demonstrate our lunar landing guidance that uses a neural network for navigation based on images of the surface. Using it for landing would require higher resolution images than we have today, but short of building a lunar GPS system, it might be more cost-effective to have a satellite assembling images from low lunar orbit.

We will also update this blog post from time to time. Stay tuned!

Lunar Topography

If you are sending a spacecraft to the moon, you will be interested in lunar topography. A new function in the Spacecraft Control Toolbox lets you superimpose a height map onto any sphere.

MoonTopoThe function RSHMoon.m gives you the Clementine spacecraft topographic data using a spherical harmonic expansion of the rangefinder data.

 

A new function, PlanetWithTerrain.m, lets you superimpose this data onto a sphere.

 

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