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      • Contactplugin-autotooltip__default plugin-autotooltip_big Contact

        If you have a burning desire to contact me, use the discussion form below. Anything you say remains private between you and me.
      • Cookie Policy & GDPRplugin-autotooltip__default plugin-autotooltip_big Cookie Policy & GDPR

        There are NO tracking cookies on this site!

        The Cookie policy is straightforward. This site only uses cookies that are required to make your experience of using this site better, and only uses session cookies (see exceptions below). Session cookies are deleted when you close your browser.
      • Downloadsplugin-autotooltip__default plugin-autotooltip_big Downloads

        Orbital Calculator Current Version This is a portable application, meaning there is no installer. Just unzip into a folder and run the executable. Since it is portable, it can be run from a USB stick.

        A full description and a list of the features are available
      • International Space Stationplugin-autotooltip__default plugin-autotooltip_big International Space Station

        This page has a portal through which you can view the current location of the International Space Station, updating in real-time. The tracker itself comes from the European Space Agency (ESA).

        Part of the tool doesn't seem to be working properly yet, raising an error when the widget first loads. A possible explanation for the error is detailed below. There is also a handy link to get email notifications direct from NASA when the ISS is visible in your night sky.
      • Mars Weather Reportsplugin-autotooltip__default plugin-autotooltip_big Mars Weather Reports

        These reports are provided by NASA's InSight lander in the south-west corner of Elysium Planitia. Daily readings are usually a couple of days behind reality (it takes time for the lander to transmit its data back to Earth).
      • NASA Image of the Dayplugin-autotooltip__default plugin-autotooltip_big NASA Image of the Day

        Date: Mon 6th July, 2020

        Title: M43: Dust, Gas, and Stars in the Orion Nebula

        Unspeakable beauty and unimaginable bedlam can be found together in the Orion Nebula Arguably the most famous of all astronomy nebulas, the Great Nebula in Orion is an immense interstellar molecular cloud only 1500 light-years away.
      • Rules on Reviewingplugin-autotooltip__default plugin-autotooltip_big Rules on Reviewing

        First off, you should know I only have a limited amount of time, so I can't review a hundred novels at once. Sorry, but that's basic physics for you. If I agree to review your novel, you may have to wait a while for me to get around to it, and then I'll need time to read it. I only review hard copies.
        • A Keen Interest In Marsplugin-autotooltip__default plugin-autotooltip_big A Keen Interest In Mars

          [MOLA globe of Mars]You may have noticed from pages such as the Mars Weather Report page, that I have a keen interest in Mars, Martian weather, and the InSight lander.

          Mars itself, and the incredible science we are doing there is of course a fascination in and of itself. However, my interest goes deeper than that. My latest novel (at the time this article was written - March 2019) is about the exploration of Mars. NASA have provided a wealth of data and information for …
        • A New Siteplugin-autotooltip__default plugin-autotooltip_big A New Site

          Yup, the old site was as ugly as sin and to find a blog entry you had to scroll through the feed or take your chances with the search option.

          This new site is just as easy to maintain, has extensive search capabilities, and both orders and structures the entries. Not only does this make it easier for you to find stuff, it encourages you to browse around. It's not as ugly either.
        • Getting To Marsplugin-autotooltip__default plugin-autotooltip_big Getting To Mars

          [Mars] Edit: updated to include

          There are multiple ways to get to Mars, and each has pros and cons. The one thing they all have in common is orbital mechanics. Some options can get to Mars in a short period of time, while others could take up to a year. Some are better suited for robotic missions, others for crewed missions. This article takes a look at the problems of getting to Mars (and getting back) and what options are available.
        • How do I Calculate Distance from Period?plugin-autotooltip__default plugin-autotooltip_big How do I Calculate Distance from Period?

          I've been asked how Orbital Calculator can calculate the distance an object is from a gravitational mass, using just its period (the time it takes to complete an orbit). The technique is relatively simple, so I'll explain it.
        • Martian Spring Weirdnessplugin-autotooltip__default plugin-autotooltip_big Martian Spring Weirdness

          [Mars (northern hemisphere)]Spring in the northern hemisphere of Mars is odd to say the least. The further the season moves away from winter, the warmer we should expect things to get, but this is not the case. It gets colder. By examining why, we can see why Earth is pretty much a special case, and begin to be able to predict weather patterns on other planets.
        • NASA Boarding Passplugin-autotooltip__default plugin-autotooltip_big NASA Boarding Pass

          I took the plunge and got my NASA boarding pass for the Mars 2020 Rover mission.

          [NASA Boarding pass for Mars 2020 Mission]

          Get yours here: NASA Website SEND YOUR NAME TO MARS
        • NASA Receives 2 Emmy Awardsplugin-autotooltip__default plugin-autotooltip_big NASA Receives 2 Emmy Awards

          NASA recently won (14th-15th Sept 2019) two Emmy's for interactive content. Aside from the obvious achievements of winning the awards, there is something else going on here that should be recognised and encouraged. Awards, of course, are intended to recognise, encourage and promote excellence, but I'm talking about NASA not only reaching out to the public, but interactively engaging them.
        • Orbital Calculator v1.0.0.5 Updateplugin-autotooltip__default plugin-autotooltip_big Orbital Calculator v1.0.0.5 Update

          You can now calculate distance from a gravitational mass using the orbital period. The image above shows a calculation for Mars which has a 687 day year.

          I've allowed the use of tokens to identify time components to make it easy to use. The examples shown in the image should explain how it works.
        • Orbital Shenanigansplugin-autotooltip__default plugin-autotooltip_big Orbital Shenanigans

          [MOLA map of Mars coloured by elevation]

          Edited: 2019-03-14

          Sometimes when you do some research – actually, quite often – you find out some really interesting stuff and end up changing your mind. In my story, I had some people on the ground on Mars, and wanted a spacecraft in a geostationary orbit above them to give them communications between them at all times. Just for info, when talking about geostationary orbits, the accepted term for Mars is aerostationary. I’ll use g…
        • Adjustment to Mars Clocksplugin-autotooltip__default plugin-autotooltip_big Adjustment to Mars Clocks

          Technically, the L describes the position of the planet around the sun from the planet's perspective. L
        • Automatic Weather Updatesplugin-autotooltip__default plugin-autotooltip_big Automatic Weather Updates

          The Mars Weather page is now 99.99% automatic, with rebuilds regularly throughout the day. The 0.001% that's not automated? Once a week I have to update the image that shows the relative positions of the inner planets. I think I can manage that
        • Hogfather Update 01plugin-autotooltip__default plugin-autotooltip_big Hogfather Update 01

          The latest version of the software this site runs on (DokuWiki) goes by the very Pratchetty name of Hogfather. There are advantages to keeping up to date with the latest version, so I've been experimenting with the upgrade process.
        • Info Reportplugin-autotooltip__default plugin-autotooltip_big Info Report

          N.B. This page gets bumped every now and again when new info is added.

          I've been pruning some of the stale articles and blog posts. If anything is broken, please let me know.
        • Mars Solar Conjunctionplugin-autotooltip__default plugin-autotooltip_big Mars Solar Conjunction

          This page is currently inactive for 2019 conjunction (until next conjunction in 2021)

          Mars is heading for a solar conjunction, which in layman's terms means it's on the opposite side of the sun from the Earth. For a short period, no commands will be sent to the Mars spacecraft (which includes landers and rovers) since the sun's corona could corrupt those commands and result in unintended actions, disablement of the spacecraft or worse.
        • Mars Weather Page Updateplugin-autotooltip__default plugin-autotooltip_big Mars Weather Page Update

          [Temperature over time] I've updated the format of the Temperature Over Time chart on the Mars Weather page to make it more readable. The sol numbers were overlapping each other, despite being broken into two rows. The chart is now interactive, in that you can use your mouse (or other pointing device) to select a position on one of the temperature graphs, and the sol number will be displayed at the bottom.
        • Orbital Calculator v2.0.6 Releasedplugin-autotooltip__default plugin-autotooltip_big Orbital Calculator v2.0.6 Released

          [Orbital Calculator v2.0.6] Four major new functions for acceleration and gravity and a few tweaks under the hood. New functions include: Constant Velocity, Free-Fall, N-Body Centre of Gravity (in 3D space) and Distance/Speed/Time.

          These powerful functions allow you to calculate speed as a constant, as constant acceleration or as increasing acceleration, as well as determine the common centre of gravity of any number of astronomical or artificial space-born o…
        • Pi Zero Planplugin-autotooltip__default plugin-autotooltip_big Pi Zero Plan

          I've been wondering what to do with my Raspberry Pi Zero, and didn't think I'd come up with an idea for a few months. Like most things, it's not necessarily a good idea to go looking for a use for it: wait until a use suggests itself.
        • Roses Fixedplugin-autotooltip__default plugin-autotooltip_big Roses Fixed

          It's taken several days, but I finally fixed the rose graphs on the Mars Weather page. The problems stemmed from the way the wiki works, ignorant caching strategies by browsers, and the joys of compiler optimisation in javascript JIT compilers (JIT = Just in time). Everything should work as expected now.
        • Site Softwareplugin-autotooltip__default plugin-autotooltip_big Site Software

          Some people have expressed an interest in what software I use for this site. It's built around DokuWiki with some extensions to make it work like a blog, keep it transparent (all the articles and entries are visible in the treeview menu) and to spruce things up - such as the auto-tooltip which displays the first part of a page when the user mouses over an internal link (this also works in the top-bar menu). Some extensions make administering the site easier, such as moving articl…
        • Updatesplugin-autotooltip__default plugin-autotooltip_big Updates

          The physical Martian clock... I have to come up with a better name for it than that. PiMars! Yup, I like that. The PiMars clock was up and running and displaying data at a crucial time. It was just a couple of hours before the end of the day at the InSight location, and as luck would have it, I had it display time at that place.
        • 2020-06-30plugin-autotooltip__default plugin-autotooltip_big 2020-06-30

          Tue 30th June, 2020 I have (on the Mars Weather page) some clocks that tell the current time at various locations on Mars, keeping both the Martian calendar and the correct Martian time (which has extended seconds). Ever since I first wrote a Martian clock, I had the extremely nerdy idea of making a physical one. I mean, what nerd wouldn't want a clock like that on their desk? It has nerd-factor 10 stamped all over it.
        • 2020-06-30aplugin-autotooltip__default plugin-autotooltip_big 2020-06-30a

          Well, it didn't take long for a disaster to occur :-D

          It's a minor thing, but a real pain in the you-know-where. I discovered my network switch didn't have any free ports on it, and I have one free on the other switch but not any cables long enough to reach it. I guess I'll have to enable WiFi on my router then. Gosh, I must turn my paranoia setting down so I can cope
        • 2020-07-01plugin-autotooltip__default plugin-autotooltip_big 2020-07-01

          Physical Martian Clock Project

          I've just been informed that the power supply unit will be here tomorrow, and I do sort of need that to get moving on this project. but there are all sorts of hurdles to get through first, so I thought I'd talk about them today, since I'm going to have to tackle them sooner or later.
        • 2020-07-02plugin-autotooltip__default plugin-autotooltip_big 2020-07-02

          The new power unit arrived, but now I have another problem. First, I need to be able to SSH into my Pi, but SSH is not enabled by default. I think that's a mistake, but you know, who am I? My big problem is I do not have an HDMI to micro-HDMI cable, so no monitor, hence the need to telnet into the device via SSH. The solution is to edit the SD card with the Pi's operating system on it, and create a file called 'ssh' in the root of the boot partition, which is enough to enable SSh whe…
        • 2020-07-05plugin-autotooltip__default plugin-autotooltip_big 2020-07-05

          It's been a few days since I last updated the progress of this project, for which I apologise. Here's what's happened:

          * The new power unit arrived * I put the Pi, screen and Case together and got it working (using the split cable) *
          • SmartSuitplugin-autotooltip__default plugin-autotooltip_big SmartSuit

            SmartSuit: A Hybrid, Intelligent, and Highly Mobile EVA Spacesuit for Next Generation Exploration Missions

            Developer: Texas A&M Engineering Experiment Station

            I think the title says it all, but just in case it wasn't crystal clear, this is what they have to say about it:
          • THE MOST Space Telescopeplugin-autotooltip__default plugin-autotooltip_big THE MOST Space Telescope

            Few telescopes can honestly say they've reinvented the concept, yet THE MOST certainly has. It works on a surprisingly old principle, by passing light through two prisms. As Isaac Newton demonstrated, this first splits light into its constituent components, then recombines it back again.
        • Dragonfly to Explore Titanplugin-autotooltip__default plugin-autotooltip_big Dragonfly to Explore Titan

          Credits: NASA/JHU-APL Few worlds excite exoplanetary chemists like Titan, Saturn's enigmatic and largest moon. It is the second-largest moon in the solar system, and the only one known to have a dense atmosphere. As such, it is seen as an analogue to the early Earth, and therefore important in understanding how life might have evolved on our homeworld.
        • How Big Is The Universe?plugin-autotooltip__default plugin-autotooltip_big How Big Is The Universe?

          [Hubble deep Field Image]

          I recently came across a youtube video explaining a method for multiplication that was quite different from long multiplication. To explain why this was so interesting, let’s first talk about long multiplication and what’s wrong with it, and then we'll calculate the size of the visible universe in centimeters.
        • Landing the Mars 2020 Rover Safelyplugin-autotooltip__default plugin-autotooltip_big Landing the Mars 2020 Rover Safely

          Autonomous landings are always fraught with danger. One of the most dangerous terrains any landing might occur on is a boulder field. Not only would the impact of the landing on these hard objects be a threat, but the boulders are likely to be jagged too. Another threat are the steep cliffs of the crater - not falling off them (although that's a possibility), but crashing into them.
        • Magnetic Field Lines on a Galactic Scaleplugin-autotooltip__default plugin-autotooltip_big Magnetic Field Lines on a Galactic Scale

          [Powerful magnetic fields are visible]

          The Cigar galaxy (M82) is already famous for the speed at which it creates new stars. The composite image shows the powerful magnetic field lines on a truly epic scale, wrapping around the entire galaxy. NASA's SOFIA observatory (Stratospheric Observatory for Infrared Astronomy - a converted Boeing 747) has shed light on what is happening.
        • Mysterious Starplugin-autotooltip__default plugin-autotooltip_big Mysterious Star

          Back in 2016, Tabetha Boyajian gave a TED talk about a star with nifty little name KIC 8462852. The Kepler space telescope had studied it and lots of other stars over the course of four years, but this one stood out.

          Also known as Tabby's Star, it is a main-sequence F-type star located in the constellation Cygnus, about 1,480 light-years from Earth. Its claim to fame of course, is that it was suggested that alien megastructures would explain the weird data that Kepler had recor…
        • NASA Got it Wrong - Oops!plugin-autotooltip__default plugin-autotooltip_big NASA Got it Wrong - Oops!

          It's not every day you get the chance to tell NASA they screwed up.

          I was reviewing the data I'd collected from NASA's Mars Weather page, and I noticed that the graphs they generated didn't match the summary data.

          For example, the summary data for Sol 169 shows the maximum temperature peaking at -17.6°C, while the graph for the same day showed the temperature never rising above -25°C.
        • Perseverance Roverplugin-autotooltip__default plugin-autotooltip_big Perseverance Rover

          The clock above targets the first (or next if that is missed) launch opportunity, which is on July 30th at:

          * * * * * * *

          Watch this page for updated information as we move closer to and beyond launch.
        • To the Moon and Marsplugin-autotooltip__default plugin-autotooltip_big To the Moon and Mars

          [The Moon - watch out, here we come (again)!]NASA has outlined an aggressive timetable for an equally aggressive return to the Moon, with a view to making the Moon a waystation for trips to Mars. This requires the development of a whole slew of new technologies, as well as ramping up existing technologies and capabilities to whole new levels.
        • Calculate your Age and Weight on the Planetsplugin-autotooltip__default plugin-autotooltip_big Calculate your Age and Weight on the Planets

          This little calculator allows you to calculate how old you would be on each of the planets in the solar system, and what your weight would be. If you have weight issues, don't look at the result for Jupiter!
        • DLCounter Pluginplugin-autotooltip__default plugin-autotooltip_big DLCounter Plugin

          [screenshot]

          This download-counter plugin for DokuWiki enables you to keep track of the number of downloads of media files such as zip, gzip, tarballs and pdf's (your choice of media formats). This plugin has been developed and tested on “Greebo
        • DLCounter Plugin Bugtrackerplugin-autotooltip__default plugin-autotooltip_big DLCounter Plugin Bugtracker

          If you have any issues with the plugin, leave a comment here.
        • Orbital Calculatorplugin-autotooltip__default plugin-autotooltip_big Orbital Calculator

          I needed to calculate orbital characteristics for any orbit around any gravitational mass (because I write sci-fi stories), so I wrote this program because I'm a programmer and I'm too lazy to do it by hand all the time. The program has expanded over the last few years, sometimes from suggestions by other writers. I make it freely available and as simple to use as possible. It now has a list of functions as long as your arm (assuming you're not a tentacle user), and the numbe…
        • Orbital Calculator v2.x Release Notesplugin-autotooltip__default plugin-autotooltip_big Orbital Calculator v2.x Release Notes

          This lists the important notes on each new release, explaining what has changed and what's new.

          See the Downloads page to download Orbital Calculator for various platforms. A full description of the product is available on the
        • Surface Gravity Calculatorplugin-autotooltip__default plugin-autotooltip_big Surface Gravity Calculator

          Want to know what the surface gravity is on any celestial object? You just need to know it's mass in terms of Earth masses (e.g. Earth = 1, Venus = 0.815, Mars = 0.107 etc.) and it's radius. This calculator will do the rest.
      • Description or Teaser?plugin-autotooltip__default plugin-autotooltip_big Description or Teaser?

        When you write the blurb that goes on the back of the book, should you write a description or a teaser? This article explores that question, explaining why each of them work and what their effects are, and why sometimes one is a better choice than the other.
      • Oh, The Facts!plugin-autotooltip__default plugin-autotooltip_big Oh, The Facts!

        [Only the facts, ma'am]There was a litany that writers used to be told, but is rarely heard these days. If you've been a writer for more than ten years you will probably recall it: “Stick to the facts!”. Does that mean your story ends up a dry, soulless, sequential list of equally dry, soulless facts? Of course not.
      • Proper Paragraph Spacing and Indenting on Web Pagesplugin-autotooltip__default plugin-autotooltip_big Proper Paragraph Spacing and Indenting on Web Pages

        This is a short article on how to setup the correct CSS in order to replicate the paragraph spacing and indenting displayed in a book on your web pages. It will also enlarge and embolden the first character in the scene.
      • Self-Publishing Trapsplugin-autotooltip__default plugin-autotooltip_big Self-Publishing Traps

        Sometimes it's a while before I post a new book review. Usually this is because I've read some self-published novels that I don't want to review. When I post a review, I'm telling readers about a book I'd recommend. This is good for readers, and it's good for the authors who get the recommendation. I'm not out to harm someone's writing career - which can always be turned around in the future - and I'm certainly not the sort of pompous umm, donkey, that simply lets my mouth…
      • Smart but Dumb Aliensplugin-autotooltip__default plugin-autotooltip_big Smart but Dumb Aliens

        We all know the problem, especially from video games and movies, where the super-smart aliens turn out to be really dumb. This is usually because the creator hasn't put much thought into it.

        So, you're creating a super-intelligent alien or species or civilisation for your short story or novel or whatever. How do you avoid the pitfalls of dumbing them down?
      • Story Structure (Hero's Journey)plugin-autotooltip__default plugin-autotooltip_big Story Structure (Hero's Journey)

        The Hero's Journey is an overlay for the 4-part story structure. See how they work in conjunction with the character arc.

        ----------

        Click on this image to review it, then click it again to see it full size

        Other Structures
      • Voices in the Darkplugin-autotooltip__default plugin-autotooltip_big Voices in the Dark

        A scene that is all dialogue and no action creates the dreaded “voices in the dark”. Perhaps they're at a conference table, or standing around talking things through before making a decision that will propel the story into its next phase.
          • Silvertongueplugin-autotooltip__default plugin-autotooltip_big Silvertongue

            [Silvertongue]

            Silvertongue is the first in a series named “Remnants of Magic”, and both the title of the novel and the series become readily apparent in the first scene. Speaking of the first scene, it's a big one at 100 pages spanning eleven chapters, but don't let that put you off - it's one hell of a scene. The story kicks you straight into the action and that first scene is a long and continuous battle - and the poor protagonist (Jon) hasn't got a clue what's going on or why…
          • Beyond Falcon's Reachplugin-autotooltip__default plugin-autotooltip_big Beyond Falcon's Reach

            Beyond Falcon's Reach by Jay Northearn, is a mish-mash of high fantasy, gothic-horror, steampunk and electropunk, with a dash of semi-intelligent machine-learning AI's thrown-in to boot. Yet for all of this, the world Northearn has created is homogenous and holistic - two watchwords I'll bang on about until the cows come home, to anyone who'll listen. Giving everything in your world a place and a reason for being there is something that every writer should always keep i…
        • The Bluffers Guide to the Quantum Universeplugin-autotooltip__default plugin-autotooltip_big The Bluffers Guide to the Quantum Universe

          [The Bluffers Guide to the Quantum Universe]

          The Bluffers Guide to the Quantum Universe is a very funny guide (read: hilarious) to things surrounding quantum mechanics. Who the major players were, how the major theories won out over each other... or didn't. Tons of interesting facts you can toss around at parties and make it look like you know what you're talking about when discussing anything to do with quantum theory, quantum mechanics, who was who…
          • Creation Machineplugin-autotooltip__default plugin-autotooltip_big Creation Machine

            Andrew Bannister’s “Creation Machine” is the best novel I’ve read this year – and that’s saying something, I’ve read some of the best sci-fi novels from the last five years in the last ten months.

            The breadth and depth of his imagination is incredible. He’s created an entire artificial galaxy, given it character and taken us on a tour that is as exciting as it is varied.
          • Iron Godsplugin-autotooltip__default plugin-autotooltip_big Iron Gods

            Another novel of The Spin, and following on from Creation Machine, Iron Gods continues in much the same vein. There are intriguing and plausible characters, a spaceship AI that has had its lobotomy reversed, strange worlds and even stranger economic forces.
          • Stone Clockplugin-autotooltip__default plugin-autotooltip_big Stone Clock

            The third outing in The Spin series from acclaimed author Andrew Bannister, Stone Clock, has a dark edge to it. Already an accomplished writer, Bannister has taken things up a notch.

            His usual mélange of lucid and slightly demented imagination is in full force, and the array of modes of humour are all present and permeate the pages as if they’d been dipped in the stuff.
          • Hard-Boiled Wonderlandplugin-autotooltip__default plugin-autotooltip_big Hard-Boiled Wonderland

            [Hard-Boiled Wonderland]

            Chris Morton is a writer with a certain pedigree, having been shortlisted for a Guardian award, this story is his third novel and his first in science-fiction.

            It tells the story of a man (Maggie Flycatcher) who has almost certainly the most boring job in history: he's a lemon tree supervisor. The creative talent that can come up with such a pointless job is one that deserves some recognition, so it instantly grabbed my attention. Flycatcher's …
          • Colony One Marsplugin-autotooltip__default plugin-autotooltip_big Colony One Mars

            [Colony One Mars] [4.5 stars]

            Colony One Mars promises to be a fast-paced sci-fi thriller, and it certainly delivers. The prologue is short and sweet, and although it doesn't offer any story information that isn't in the story proper, it does set up the atmosphere for what is to follow. The tension ramps up very quickly and most unexpectedly, and everything changes before we've had a chance to grab our breath.
          • Colony Three Marsplugin-autotooltip__default plugin-autotooltip_big Colony Three Mars

            [Colony Three Mars by Gerald M. Kilby] [4 Stars] The third instalment in the saga is even messier (for the protagonists) than the previous two, ramping up the tension and the action, and making the solution even harder for the reader to predict. The cast of protagonists has grown a little, but that's fair because the cast of antagonists has too.
          • Colony Two Marsplugin-autotooltip__default plugin-autotooltip_big Colony Two Mars

            [Colony Two Mars] [4 Stars] Colony Two Mars picks up the story a few years after the preceding story, Colony One Mars left off. I really enjoyed the first instalment in this trilogy, but this is a much better, much stronger story. As the overarching story of the trilogy begins to emerge, Kilby's eye for a good story starts to pay dividends.
        • Science Fiction Double Featureplugin-autotooltip__default plugin-autotooltip_big Science Fiction Double Feature

          [Science Fiction Double Feature ]

          This pair of novellas comes courtesy of Zombie Pirate Publishing, and indeed the stories themselves come from the publishing house's founders and resident editors, Sam M. Phillips (Into the Eye) and Adam Bennett (Phosphorus).

          Since they come as a pair it is necessary of me to review each in turn before giving an overall impression, and I've chosen the order they appear between the covers.
    • DokuWikiplugin-autotooltip__default plugin-autotooltip_big DokuWiki

      wiki:dokuwiki DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database. It is loved by users for its clean and readable Formatting Syntax. The ease of maintenance, backup and integration makes it an administrator's favorite. Built in
    • Formatting Syntaxplugin-autotooltip__default plugin-autotooltip_big Formatting Syntax

      DokuWiki supports some simple markup language, which tries to make the datafiles to be as readable as possible. This page contains all possible syntax you may use when editing the pages. Simply have a look at the source of this page by pressing
    • Welcome to your new DokuWikiplugin-autotooltip__default plugin-autotooltip_big Welcome to your new DokuWiki

      Congratulations, your wiki is now up and running. Here are a few more tips to get you started.

      Enjoy your work with DokuWiki,

      -- the developers

      Create your first pages

      Your wiki needs to have a start page. As long as it doesn't exist, this link will be red:
blog:articles:software:orbital_calculator

Orbital Calculator

Orbital Calculator v2.0 displays results in many different equivalences

I needed to calculate orbital characteristics for any orbit around any gravitational mass (because I write sci-fi stories), so I wrote this program because I'm a programmer and I'm too lazy to do it by hand all the time. The program has expanded over the last few years, sometimes from suggestions by other writers. I make it freely available and as simple to use as possible. It now has a list of functions as long as your arm (assuming you're not a tentacle user), and the number of downloads is now in triple digits.

I wrote Orbital Calculator to handle just about any proposition. You can add new gravitational masses (the things you want to orbit) for easy and consistent recall. You can add satellites too, so you can recall their orbital data at any time. You can create temporary calculations (not stored for later recall), and you can edit orbital parameters without changing the stored data, so you can play “what if…”.

Even better yet, you can export any data for satellites or gravitational masses – choosing exactly which ones to export – and share the files with other users, who can import them into their own databases.

It runs on Windows & Linux (32-bit and 64-bit versions available for both platforms), and there is an armv7l version too (can you say Raspberry Pi?).

Note: you can click on any of the images to display them full size

Release Notes & Download

For the latest release notes, go to the Release Notesplugin-autotooltip__default plugin-autotooltip_big Orbital Calculator v2.x Release Notes

This lists the important notes on each new release, explaining what has changed and what's new.

See the Downloads page to download Orbital Calculator for various platforms. A full description of the product is available on the
page.

If you want to jump straight to the download, there are links to it in the top-bar menu and at the bottom of this article, else you can jump to the Downloads pageplugin-autotooltip__default plugin-autotooltip_big Downloads

Orbital Calculator Current Version This is a portable application, meaning there is no installer. Just unzip into a folder and run the executable. Since it is portable, it can be run from a USB stick.

A full description and a list of the features are available
here.

Two Types of Orbital Calculation

Two-body calculationUsers of the first versions of this program will be aware that the basic computation the program makes is for a satellite with an insignificant mass (vs the host gravitational mass). Simply select a mass and enter an orbital distance by typing in apogee and perigee (or just one for a circular orbit), then hit the calculate button. This is great for satellites and other types of spacecraft.

You can now also perform two-body calculations by selecting two gravitational masses and the distance between them. This will try and take into consideration a whole star-system full of planets by using the Solar system as a blueprint. It then compares this to the Newtonian/Kepplerian equation results and determines which is likely to be most accurate. This increases the precision in most cases.

Additional Enhancements

Version 2 of the software makes many minor adjustments 'under the hood' to eliminate or reduce rounding errors and increase precision. This convenience is carried forward into the user-interface. Wherever it makes sense, for example, the Calculate button has been removed allowing the program to calculate (and recalculate) as you type. A Copy to Clipboard button has been added on most result screens for improved convenience.

There is now an embedded context-sensitive help system, with many of its pages filled with additional information. For example, there is an explanation of gravitic time-dilation - did you realise you are not experiencing time at 'full speed'? Gravity dilates time, and not just around super-massive black holes.

Gravitation and Motion has been enhanced

Speaking of gravitic time-dilation, the program can now calculate time-dilation for objects in orbit, taking into consideration both the gravitic and acceleration dilations (one is positive, the other negative). Using the ISS as an example, you can now calculate the dilation crew members are subject to, to within 0.0037 seconds per year accuracy.

The Gravitation and Motion screen now calculates gravity, gravitational acceleration and escape velocity at the elevation you specify, as well as at the surface.

Wherever it is appropriate, you can now select AU (astronomical units) and meters as the unit of measure for both input and results.

The layout of all the screens have been redesigned to be easier to read and consistent. This makes using the program a much more pleasant experience.

Lagrange Points

Lagrange Points can now be copied to the clipboard

Calculating Lagrange points epitomises one of the simple yet effective enhancements littered throughout the program - the Copy to Clipboard button.

The clipboard data has been tidied too, so it now uses spaces instead of tabs to align the data, making it much more compatible with writing programs and note-keeping software.

The Lagrange points are usually calculated as the distance from the center of each of the two gravitational masses. In the real world though, you often want the distance from the surfaces of these bodies. For example, if you want to place a satellite at the Earth-Moon L4 Lagrange point, it is much more useful to know the location is 395,958 km from Earth and 400,597 km from the Moon. This also allows you to calculate the communications delay from the surface of one of these bodies and the satellite.

Database Maintenance

Enhanced, easier to use database maintenance

The database maintenance screens have been enhanced for much easier use. You no longer have to select which objects to display before entering the maintenance screen. Simply enter the screen and use the real-time filters to select which objects to display. Hovering over data in the 'Mass' and 'Surface Gravity' columns will reveal values in greater precision.

Wherever a value is less than (but not equal to) 0.00, youll see a ~ beside it to indicate this. Hovering over the value will, as stated above, reveal greater precision. For example, you can see the surface gravity of Betelgeuse is ~0.00. Hovering over it will display 0.0003.

New Features

An additional 11 new features have been added to the program, almost doubling its previous list of functions. Some of them are subtly embedded in pre-existing functions, so don't expect them all to have menu options of their own, but they all add up to make the software much more useful and easier to use.

One of these functions is the ability to enlarge the window contents by zooming in or out (without resizing the window). This is handy if you have issues reading the text at its natural resolution.

You are now able to control how frequently the program checks for updates - from every time the program is launched to no more than once per month. You can even disable update checking if you wish. This can be controlled on the new Preferences Screen, where you can also instruct the program to restore window sizes and positions and the zoom level.

New Database Format

Version 2 includes a new database format which brings several advantages. For example, 'repeat last calculation' now works even if you have deleted both the host mass and the satellite from the database.

This makes the version 1 database files incompatible with the new format. Never fear though, Version 2 can recognise and import from version 1 databases (so all your lovely data isn't lost), and you can even import from version 1 export files. Unfortunately you can't do it the other way around, but honestly, why would you want to?

Feature List

  • N-Body Centre of Gravity calculate centre of gravity for any number of gravitational masses
  • Constant Acceleration - all 5 components of teh constant acceleration equations can be deduced and converted
  • Free-Fall distance and final velocity for increasing rate of acceleration over any gravitational mass for any duration
  • Distance/Speed/Time calculations and conversions
  • Schwartzschild and Photon Sphere radii calculated as a factor of mass
  • Synodic Periods calculated from orbital distances (and central mass)
  • Synodic Periods calculated from orbital periods
  • New Objects added to database - six stars and one more asteroid
  • Automatic Calculation wherever it makes sense, so you don't have to hit a 'calculate' button
  • Copy to Clipboard on most result screens
  • Database Stats now provides totals
  • Repeat Last Calculation now works even if you've removed both the host mass and satellite mass from the database
  • Import Data recognises v1.x import files and databases (so you can import directly from an old database)
  • Export Data to prune a database, separate project data or to share with friends
  • Preferences to control update checking, restoring window sizes and positions
  • Gravitation and Motion to calculate gravity, escape velocity and gravitational acceleration at the surface and at an elevation
  • Lagrange Points calculated as distance from the surfaces of the host and satellite mass
  • Two-Body Orbits taking into consideration the masses of both host and satellite
  • Hohmann Transfer Orbits for low-energy migration
  • Distance Between Two Stars using star-chart coordinates
  • Apparent Magnitude of a star from another star
  • Distance from Period when all you know is the host mass and and the orbital period
  • Satellite Footprint from Altitude
    • Visible Surface of host mass as %
    • Latitude spread of the footprint across the surface
    • Diameter of footprint
    • Radius of footprint
    • Surface Area of footprint in square kilometres
    • Maximum Period of Visibility of satellite from the ground
  • Visibility over Horizon How far from an object (e.g. mountain) can you be and still see it?
  • Age from Orbit calculate someone's apparent age from local years
  • Age and Weight on Solar System Planets
  • Calculate Habitable Zone (a.k.a. Goldilocks Zone) around a star
  • Time Dilation from Velocity where velocity is a factor of the speed of light
  • Time Dilation from Orbit factoring both gravitational time dilation and acceleration time dilation
  • Context-sensitive Help
  • Zoom-in, Zoom-out if things are a little hard to read
  • Password Generator to generate very strong passwords for those pesky internet logins
  • Multi-Platform it runs on Windows, Mac and Linux
  • 64-bit versions available for all platforms
  • 32-bit versions available for Windows and Linux
  • Portable means it doesn't have to be installed - just unzip and run. Can be run from a USB stick.

Download

You can download the latest versions from the Downloadsplugin-autotooltip__default plugin-autotooltip_big Downloads

Orbital Calculator Current Version This is a portable application, meaning there is no installer. Just unzip into a folder and run the executable. Since it is portable, it can be run from a USB stick.

A full description and a list of the features are available
page (there's also a link to the page in the top-bar menu).

N.B. Windows and Linux versions are now available in both 32-bit and 64-bit flavours. I'll add a Mac version as soon as I can find someone to test it for me (feel free to volunteer!).


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blog/articles/software/orbital_calculator.txt · Last modified: 2020/05/31 18:41 by Phil Ide

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