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A series of four videos are now up on Youtube showing how to use the spreadsheet panning tool to get out to the Moon. Spreadsheet trajectory planning tool The goal here is not to build a tool that is a replacement for TransX and IMFD. Rather, the intention is to show that accurate trajectory...

A youtube video describing basic operation of the spreadsheet-based trajectory planning tool is now up. A spreadsheet-based trajectory planning tool A four-part series on using this tool to get to the Moon will be posted over the next few days. Using the spreadsheet tool, and aside from the...

Yes, it is almost certainly more accurate. Long run accuracy is the 'raison-d'eire' of these ephemeris engines so, it really ought to be more accurate than the much simpler Mars 24 calculations. Many users of VSOP87 don't need to update screen displays in real-time, so speed of calculation...

These perturbations schemes are specific to each planet. So, the table would have to be re-worked for Venus. My guess is that you want a more accurate determination of Venus' position. If you really want accuracy for Venus, you might want to look at...

Hi, ncc1701d The key difference, I suspect, is that I have changed the default setting on the "Error limit" in the configuration files for the Sun and the planets from the default vale of 10^-6 (or variously 1-^-8) to a uniform 10^-11. According to 'martins', this forces Orbiter to use the...

Orbiter is itself quite a powerful ephemeris generator. According to Orbiter's "Orbit MFD", the Mean Anomaly of Venus at epoch J2000 (ecliptic reference frame) is 50.11 degrees (to two decimal places of accuracy). To get this value, open any scenario in Orbiter; then load up the Scenario...

Hi, Notebook Dropbox is slightly irritating because, if you don't have a Dropbox account, after hitting the 'Download' button, it asks if you want to create an account. To download the file, you then hit the ""No thanks, continue to download" button and the file should download to your normal...

Well, here it is: the first iteration of the Excel speadsheet-based integration engine (download from https://www.dropbox.com/s/02q6i20at94b9r6/S4INT.zip?dl=0). Believe it or, this is a usable, precision trajectory planning tool. It is accurate (some might even say very accurate), but as...

This is the third post in a short series setting out how to use Microsoft Excel to build a high-fidelity trajectory integration engine with a view to using that engine to target, say, the Lagrange points of the Earth-Moon system. Microsoft Excel has been chosen in this instance because most...

Well, I've found a little time this weekend to work on this little project, so time for an addition the preceding post. First a quick recap: The goal here is to develop a spreadsheet-based, but highly accurate, co-integration scheme to help getting to difficult to reach places - such as the L1...

In Orbiter, to do anything useful, you need to know the future trajectory of your spacecraft so that you can ensure that you are 'on target'. Usually, the standard Orbiter MFDs of TransX and IMFD's Map program will give you the information that you want to achieve whatever you mission goal you...

If you use a Mac, have you tried Wineskin Winery? This is a good way of running Orbiter on an emulated Windows XP system. Wineskin creates a 'wrapper' - in effect, a 'ew' bare-bones XP system - which can then run .exe and .msi files by having the wrapper point to the correct executable file...

I've thought a bit more about getting to EM L1 from Low Earth Orbit (LEO) in Orbiter and this post sets out my take on what you need to do to get there. I've tested this approach in Orbiter and, although it lacks pin-point precision, it is a perfectly serviceable way of getting to L1...

Yes, that sounds about right for the Elliptic Restricted Three body Problem. Yes, the Lagrangian points are not 'fixed'. Yes, you can. When the Moon is at periapsis in its orbit around the Earth, the L1 is around 53324 km; and when the Moon is at apoapsis it is 59316 km. So, since you can...

There are better ways of getting to L1 from LEO - but the ways that I know of require the a 'home-grown' trajectory planning tools that use: 1. an n-body (or at least three-body - Earth / Moon/ spacecraft) integration engine; 2. application of a 'shooting method' to a time and speed to leave...

I was giving a little more thought to this question the other day. Although my views are hardly definitive, I think that the area to focus on is using PyKEP/PyGMO as a tool for making a series of mid-course corrections by way of re-optimising the trajectory plan based on the spacecraft's...

wrt the multi-revolution Lambert Solver: there are a few papers floating around the internet on multi-period Lambert Solvers. And it is possible to build your own. But probably the easiest thing to do is to download someone else's algorithm rather than re-invent the wheel. Personally, I...

With respect to IMFD's Course Program: basically, you can't. IMFD's Course Program implements a single revolution Lambert Solver (which solves the boundary value problem: "I'm at point A and I want to be at point B at time dT in the future. What change in velocity should I apply now to get to...

Let's suppose that you want to make a transfer from Earth to Mars. The patched-conic approximation has a hyperbolic departure from Earth (with the central mass of the 2-body approximation being Earth); an elliptical transfer from Earth to Mars (with the central mass of the 2-body approximation...

Yes and no. IMFD's Map Program does indeed take into account n-body interactions, but my experience of it is that it is not always reliable. Better, methinks, to build a bespoke n-body integrator. IMFD's Course Program does have a Lambert Solver - but it is not a multi-period solver.