Navigation – Earth to Mars Delta V
by Tim Blaxland – Introduction by Robert Brand
I have not yet introduced you to our Navigation chief Tim Blaxland and I will do that soon enough. Let us just say that he knows his stuff. When I was requested to make Mars the destination of the first shakedown flight of the ion engine equipped ThunderStruck craft in 2022, here was his initial response. This may go over a few heads, but it may be important for you to know that we have the ability to actually do the work required. What we don’t know about building and operating a spacecraft will be firmly supported by the right staff with the right experience and credentials – when the time comes. Until then, please understand that we are a capable team and soon to become a space sector company. I hope that you find this email interesting. I will post some orbital pictures when we have them ready for publication in a week or so..
The importance of this work was to ensure that 2022 provided a window of opportunity to leave for Mars. Here is Tim’s email:
These graphs show the arrival, departure and total delta-V requirements for Hohmann-type Earth-Mars transfers. Delta-V is displayed by colour, the horizontal axis is departure date (range Jan 2020 to Feb 2025) and the vertical axis is flight time (range 100 days to 500 days).
I know these aren’t what you were looking for, but they are relatively easy to produce and are moderately interesting. They are based on a simplified calculation method using instantaneous changes in velocity for Earth escape and Mars capture and do not consider things like ion engines which can be used to lower the departure and capture delta-Vs.
At least they give you a useful ballpark approximation of when the available launch windows are.
You’ll notice that there are two lobes to each patch. The lower lobe is the one typically used for conventional chemical rockets because they give a much lower flight time (7-9 months) without too much delta-V penalty. The associated transfer orbit does however have a relatively high eccentricity. They top lobes have longer transfer times but lower eccentricity and I believe they will give us greater opportunity to maximise the use of the ion engines but I need to do more research in this area.
Earth to Mars Delta V:
Tim will be giving me a better breakdown of the navigation profiles, but 2022 is such a long way and we may slip or gain over the years, so it will be little more than an exercise to ensure we understand the time taken with an ion engine and the problems that may arise. I look forward to more detail soon and I will share it with you.