Earth To Mars Checklist
Checklist for using the TransX MFD in the
Orbiter Space Flight Simulation
Orbiter Space Flight Simulation
by Cpt_CryBaby
Last Updated 11 Jan 2010
ATTENTION! This checklist has not been verified in the newest version of Orbiter (2009).
This is my step-by-step procedure for getting to mars from earth using the TransX MFD. Many
thanks to Duncan for this excellent navigational tool. As always, where would we be without Martin?
He has made the world a better place.
This checklist is aimed at beginners. I don't claim to be an expert. All I'm saying is that the
following procedure gets me to mars. This checklist is based on the tutorials and manual posted
on Duncan's site. I've filled in some of the holes with a more detailed checklist based on my limited
experiences. Admittedly, this checklist wanders so please take it with a grain. Experienced
navigators can provide corrections where I've strayed or fallen short. Everyone is welcome to
add/comment. I will post all relevant feedback.
I apologize in advance for all type-Os, spelling and usage errors. My writing sux but I think the
points get across to the reader.
This checklist assumes familiarity with the basics of orbital mechanics. If you haven't docked with
the ISS a couple times, then much of this won't make sense. Go here for my rendezvous/docking
checklist.
Here we go!
==
Make sure you've turned fuel consumption off in the launch pad or are flying a ship with low fuel
consumption characteristics. I used the Event Horizon by Brainstorm which is an excellent ship to
use for learning interplanetary travel. It is very responsive in both linear and rotational thrusters for
such a large ship. Make sure that the ship you choose is fully functional with both rotational and
linear thrusters.
Go here for a procedure to check that your ship does not have spaces in its name. You will not be
able to save your TransX work to scenarios that have ships with spaces in their name.
1. After launching Orbiter, switch to cockpit view (F1) and launch the transx mfd (shift + j)
2. Ensure that 'view' is set to 'setup'. If it is not, cycle through view settings (shift + w) until 'setup'
is selected.
Note: Most variables in the transx are selected by cycling through a list of available settings. Each
list is of different lengths so the instruction of "(shift + w)" means "cycle through the list using 'shift +
w' until the appropriate value is selected." This will clean up the checklist by excluding instructions
of "do this twice" or "cycle until" etc. etc. Yer just gonna have to pay attention! :)
3. Change 'select target' to 'escape' (shift + '+') [which means hold down the shift key and hit the
'+' key until 'escape' is selected.]
4. Create a new stage (shift + f)
5. Select target planet 'mars' (shift + '+'). The inside blue circle is earth's orbit. The outside blue
circle is mar's orbit. The sun is the "+" at the center. Where the straight lines intersect the circles
shows you where each planet is on their orbit.
6. Change 'view' to 'eject plan' (shift + w)
7. Select 'prograde vel' variable (shift + >)
8. Increase the value of 'prograde vel' (shift + '+') to see the hypothetical orbit that this thrust
would create. Continue to add thrust until the dashed orbit moves out from the earth and
intersects with mar's orbit (the outside blue circle). The most efficient trip will be one where the
orbit of your ship just barely reaches the orbit of Mars (meaning it reaches mar's orbit but does not
overshoot). If you overshoot, (shift + '-') will decrease thrust.
9. Change variable to 'eject date' (shift + >)
10. Change the date by moving FORWARD (shift + '+') until the two straight dotted yellow lines
match up or get very close to each other. You must move forward since you are trying to
determine what your launch window will be in the future. As the date is adjusted, the dashed lines
might be coming together nicely and then they suddenly jump to totally new positions. Orbital
mechanics are finicky and sometimes they just can't work out for a given situation. Don't worry!
Keep moving the date forward in time and eventually the lines will coincide.
Note: Planetary orbits are ellipses and usually offset from each other. So as you rotate the date,
you might find that the hypothetical orbit (green dashed line) that previously reached out to Mar's
orbit now falls short or maybe overshoots a bit. If this happens, jump back to step 7 and add or
subtract thrust until the ship's orbit is tangential to mar's orbit again.
During many steps of this process of getting to mars, it will be necessary to jump back and forth
between steps to fine tune the plan. Changing one variable may throw an old variable out of whack
so you have to go back and adjust.
11. Using (shift + >), hop between and adjust the variables 'prograde vel','eject date', 'ch plane'
and 'outward vel' until 'cl. App' (closest approach) is as small a value as possible. Use (shift + '+')
& (shift + '-') to adjust each variable.
Note:
k = km
m = 1000km
g = 1,000,000km
t = 1 billionkm
Use (shift +{) to pump up the sensitivity of each variable. This will allow you to fine tune your
approach in smaller increments.
The levels of sensitivity are:
course
medium
fine
super
ultra
hyper
NOTE: Don't labor too much on reducing your approach. At least one correction burn will be
required on the way to mars and variances can be corrected then. Anything below 50k is sufficient
for now.
12. Once you are satisfied that 'Cl. App' is as low as you are willing to get it, switch variable to
"eject date' (shift + >) and write down the MJD.
13. Return to stage one (shift + r). You should now see a graph of the earth with the hypothetical
orbit represented as a curved dashed line.
14. Change 'view' to 'escape plan' (shift + w)
15. Change 'variable' to 'pe distance' (shift + >). This is where you set the distance of the
periapsis above the earth. Add or subtract (shift + '+' OR shift + '-') until 'pe distance' is 6.505.
Fine tune as needed (shift + {). Here are a couple graphs that may help.
Note: I've deviated a bit here from other checklists and hopefully some of you vets can clarify. The
tutorial on Duncan's site calls for a periapsis much lower than this. When I tried it, I crashed and I
think it was because of atmospheric drag. I read someplace (or was told) that earth's atmosphere
ends at 134km. If this is added to the earth base distance of 6371, the periapsis would be 6505.
Right or wrong, let's proceed with 6505 as our chosen distance. I'm guessing that it may not matter
exactly what value periapsis is set at since the transx will adjust for whatever you select. The idea
is get as low as possible for your burn. This will put you at maximum velocity and every km/h helps.
=
Congratulations! You've identified and recorded your launch window! You have also set up your
flight plan in the transx mfd.
Now all we have to do is follow through on that plan.
=
We will now time warp to one day before burn.
Note: Go here to see Rob's alternative to steps 16 - 21. I tried to advance time in the Scenario
Editor but it caused a lock up for me. You may have better luck.
16. Exit Orbiter and 'save current' as E2M01.
17. This step is weird but hang with it: Launch the scenario that you just created (E2M01) in
Orbiter. Quit out and save AGAIN as E2M02. What is this all about?
18. Close out launch pad. Navigate your files and find E2M02 where it lives on your computer.
For most of us that will be:
start/my computer/local Disc C/Program Files/Orbiter/Scenarios
Your computer may have a different file structure. If you can't find the file, do a search.
19. Dbl click on E2M02. It should open in notepad. If it doesn't, close out, launch notepad and
then open the file E2M02.
20. Close to the top of this document, you will see the line "Date MJD #####.#######". Change
the MJD to one day BEFORE the launch window that you copied down in step 15.
Example:
If you wrote down 52799.3435
Change MJD to 52798.3435
21. Save this document using 'file' and 'save'. Do not rename it. Save it as the name it currently
has which should be E2M02. Exit Notepad.
What did we just do and why?
22. Launch E2M02 in Orbiter. You are now exactly one day away from optimum ejection burn.
There are a few things left to do before we make our burn to mars so get your ship up and in orbit
asap. An orbit around 7000 with a low eccentricity will do nicely for now.
We are taking liberties that won't work when flying a 'real' ship with limited fuel. There are ways to
optimize takeoff and align with the target at the same time. However, for simplicity, this checklist will
break these actions into separate steps. After you've gone to mars a couple times with this
checklist, you can research and experiment with ways to maximize efficiency.
23. In your left MFD, change 'view' to 'escape plan' (shift +w). Change 'variable' to 'ej orient'
(shift + >). The solid green straight line is your ship. The grey straight line shows the points where
your current orbital plane intersects the orbital plane of your target (mars).
You will use this information in the next step as you would with the standard 'Align Orbital Plane'
mfd to align your orbital plane with mars' orbital plane.
24. This step was integrated into step 23. Please move on.
25. Rotate your ship to '+normal' and time a burn to straddle either point where the grey line
intersects your orbit. The goal is to reduce 'Rel Inc' to a value as close to zero as possible.
If 'Rel Inc.' increases when you hit the gas, switch quickly to a retro thrusters.
Note: Unlike the standard 'Align Orbital Plane' mfd, the duration and timing of the alignment burn
are not computed for you. Use what you have learned about the 'Align Orbital Plane' mfd to make
your best guess about when to initiate this burn. It will probably take 2 or more burns using steps
23-25. Continue making burns until 'Rel Inc.' is as close to zero as possible.
Note: The open diamond on the grey line is the descending node (DN) if approaching it, use your
normal ( [ ) attitude for burn. The closed diamond is the ascending node (AN) if approaching it,
use your anti-normal ( ] ) attitude for burn.
26. Rotate your orbit so that your periapsis matches the hypothetical periapsis (green dotted
straight line) on the transx graph. How do I do this?
Still confused? Check out this graphic, it may help
After you have eyeballed this alignment, set your right mfd to 'orbit'. At a point halfway between
your apoapsis and periapsis, point ship prograde, use linear thrusters (num pad 6 & 9) to match
the 'T to Pe' from the Transx with the 'PeT' from the 'orbit' mfd. This takes some patience as you
are shooting at a moving target.
27. Set your right mfd to 'orbital' (shift + o). The next time you reach apoapsis, execute the
necessary burn to move your periapsis to the predetermined altitude of 6505.
Note: It is very important that all remaining burns in earth orbit happen as close as possible to
apoapsis and periapsis. To burn at any other point will tend to undo the periapsis alignment that
we just made in step 28.
28. The next time you reach periapsis you may want to execute a burn to move your apoapsis to
an altitude of approx 6600. Ensure your apoapsis doesn't dip below 6505 or it will flip with your
periapsis and cause confusion.
29. Check again that 'T to Pe' from the Transx matches 'PeT' from the 'orbit' mfd. They may have
become dis-aligned on subsequent burns since step 26. Small variances can be ignored but if
they are off substantially, go back to step 28 and line up your periapsis again.
30. Exit Orbiter and 'save current' as E2M03. It is a good idea to save at this point in case
something goes wrong with the burn. Should things go wrong, you can go back and relaunch from
this point.
31. Launch your newly saved scenario (E2M03). Ensure ship is oriented to 'prograde' ([). Set
your right mfd to transx (shift + j) but advance it to stage 2 (r shift + f) while leaving the left mfd in
stage 1. Ensure 'view' is set to 'escape plan' in left mfd (l shift +w). Monitor 'T to Pe' on left mfd.
This is the countdown to burn. When this countdown reaches 30 seconds, (at the appropriate
MJD that you wrote down in step 15) initiate ejection burn. This will be a long burn. While you are
depressing the '+' key on the number pad, hit the left 'ctrl' key and release both. Your main
engines should now remain at full thrust.
Note: (num pad *) will kill main engine burn.
32. As you burn, monitor 'T to Pe' on the TransX mfd. When it reaches zero, use the 'num pad 5'
key to kill rotation. You no longer want the thrusters to adjust for prograde.
33. Continue to burn while monitoring 'DeltaV' in the left transx mfd. Burn until this value is as
close to zero as possible. You can alternately watch the right mfd and see the actual orbit (solid
green) expanding outward from earth orbit (blue) towards the hypothetical orbit (dashed green).
This will help you anticipate when to shut down the main engine burn and fine tune it with linear
thrusters.
34. When 'DeltaV' is zero, or as close as you are willing to get it, shut down all engines. You are
now on the way to mars.
35. Pick a port with the best view of earth. Crack open a cold one and enjoy the view as you leave
earth behind.
==
Now is a good time to discuss time acceleration. Interplanetary travel takes weeks, months, even
years depending on where you go. You will want to use time acceleration to get thru the boring
parts. Time acceleration is accomplished with the 't' and 'r' keys. IT IS IMPORTANT that you do
NOT accelerate time beyond 100x while close to space bodies. If you do, you can put your ship
into an uncontrollable spin. Wait until you are several diameters ( 5 - 6 ) away from a space body
before accelerating beyond 100x.
ALSO
While you are accelerated beyond 100x it is imperative that NO ENGINES OR THRUSTERS ARE
FIRING. This includes prograde, retrograde or normal/anti normal attitude controls. Failure to
ensure all thrust is at zero can put you into uncontrollable spins and/or foul up your flight plan. Be
aware: Uncontrolled spins can destroy marriages, cause you to throw your joystick and tempt you
to kick the dog/cat/hamster. Avoid a spin at all costs.
It is advisable to turn off the rcs (shift + num pad /) when not in use. This helps eliminate accidental
bumps from the joystick.
Until you get the hang of it, I advise saving before you accelerate time.
36. Keep an eye on the left transx mfd. When you have escaped the earth's influence, it will
change automatically to stage 2. At this point, we will make our first correction burn.
NOTE: We will make a burn now but in reality you would wait until you are further away from
periapsis. When possible, burns should be made as close to apoapsis as possible. This will save
fuel because a ship closer to apoapsis is moving slower. The lower your velocity the lower your
mass. It is far easier to adjust the motion path of a lower velocity ship, hence the fuel savings.
Because we have unlimited fuel, we will break this general rule and make a correction burn now.
NOTE: Many orbinauts employ the "1/2" rule. They make a correction every time they travel half
the remaining distance to their target.
37. Because both mfds are now showing the same info, you can power down the right mfd.
38. Switch 'view' to 'manoeuvre' (shift + w)
39. Change variable to 'maneuver mode' (shift + >)
40. turn 'manoeuvre mode' 'on' (shift + '+')
41. Using the variables (prograde vel, outward vel, & ch plane). Adjust each to bring 'cl. app' to
smallest value. (Shift + '+' OR Shift + '-') as needed.
(Shift + {) will adjust the sensitivity of these variables for fine tuning.
42. When cl. App is lowest possible value, switch 'view' to 'target' (Shift + w). We will now burn our
engines according to the hypothetical info we just discovered in step 41.
43. Rotate ship until the "x" centers in the graph.
44. Fire engines until 'Delta V' is as close to zero as possible. Use linear thrusters to reduce 'Delta
V' as low as possible.
45. Change view to 'manoeuvre' (shift + w). Change variable to 'manoeuvre mode' (shift + >).
Turn 'manoeuvre mode' off (shift + '+').
Important note: The 'manoeuvre mode' must be turned off when it isn't being used to
perform a correction burn. If you don't reset the mode between burns, you'll be planning your burn
using old information.
46. As you progress to mars, small course corrections can be accomplished with linear thrusters.
Point ship to prograde ( [ ). Fire linear thrusters as needed to reduce 'Cl App' (closest approach)
to its lowest value.
Note: After long periods of time acceleration, these small corrections may become ineffective. If
so, go through steps 38-44.5 to perform a major correction burn.
47. Make corrections (using steps 38 - 44.5 or step 45) as desired to keep 'cl. App' as low as
possible.
48. Break out the chess board--it will be a long trip.
49. Monitor your progress:
Set one of your mfds to transx (Shift + J)
The inside blue circle is earth's orbit. The solid blue line shows where earth is on that orbit.
The outside blue circle is mar's orbit. The solid blue line shows where mars is on that orbit.
The solid green ellipse is your ship's orbit. The solid green line shows where your ship is on that
orbit.
The grey line indicates the point of intercept as computed by all your actions up to this time using
the transx mfd.
Be patient. Continue to correct your course as desired and wait for the intercept point. Once you
can see mars, you will be tempted to point your nose at it and try to 'rocket' on over. This might
work when approaching the ISS but taking this action on a planetary scale will get you lost in space.
Distance and direction are deceptive in space. Don't trust your eyes, trust your flight plan.
==
There are no easy answers or exact step-by-step for the remainder of your mission. It is best
described as tweaking variables in the maneuver mode to create a hypothetical capture/insertion
and then following through on that plan. This requires a lot of jumping back and forth between
variables and playing with the sensitivity (shift + {). If you have the sensitivity set too low, you can
often jump across the desired value which produces quite a bit of tail chasing. It will take some
experience for you to become comfortable. Take your time and pay strict attention to what you are
doing. Learn a little each time and soon it will be almost second nature.
In this set up burn, your main concerns will be to set your minimum altitude and reduce your
inclination as much as possible.
50. Time accelerate ( 't' key ) until the green line (your ship) almost coincides with the grey line
(intercept point) then return to time normal ( 'r' key ).
51. Power up the right mfd as transx. Advance to stage two (shift + f). Change 'view' to
'Encounter' (shift + w). Minimum altitude (Min Alt) and inclination (inc) can be read from the right
mfd. If your current trajectory will cause an impact with your target, you will see surface
coordinates instead of an altitude reading.
52. Change left mfd to 'View: Maneuver' (shift + w). Change variable to 'maneuver mode' (shift +
>) and turn maneuver mode to 'on' (shift + '+')
52.5 For this step we want to avoid using the 'man. date' variable. We are getting very close to
our insertion burn and if we advance the maneuver date too far into the future it will exceed the
insertion point.
53. Using the 'prograde vel', 'outward vel' and 'ch plane' variables, tweak with (shift + '-') or (shift +
'+') to set 'min alt' between 200k and 250k (read from right mfd) and to get 'Inc' down to its lowest
value. Use (shift +{) to adjust increment sensitivity and fine tune. Lots of patience here!
Note: In general, the lower the better but getting your Inc below 30 degrees is good enough.
54. Step deleted. Please move on.
55. Change 'view' on left mfd to 'target' (shift + w). Use rotational thrusters to center the green 'x'
on the graph. Fire engine until 'Delta V' is reduced to lowest possible value. Use linear thrusters
to fine tune.
56. Change 'view' to 'maneuver' (shift + w). Change variable to 'maneuver mode' (shift + >). Turn
maneuver mode 'off' (shift + '+').
You have now established a low pass on your target (mars) at the smallest inclination.
==
Again, no easy answers or exact step-by-step to be had. Pay strict attention to your readouts as
you adjust your variables. Pump up sensitivities early to avoid jumping over desired values.
The basic goals when setting up insertion are:
Minimum altitude between 200k & 250K
Inclination is at its lowest possible value (ideally less than 30 degrees)
'H Pe MJD' matches 'Pe MJD'
Work to get the tightest orbit possible
57. If both mfds are not on, power them both up. Advance right mfd to 'encounter' (shift + f).
NOTE: Be careful with your acceleration. You are used to accelerating to pretty high multiples due
to your long voyage but now you are getting back to coping with your trip on a planetary level. You
should not accelerate beyond 10,000 from this point on. If you do, you may find that you pass
mars or get way too close before you have time to decelerate.
58. Time accelerate (t) until the left mfd switches over to 'encounter'. This will happen
automatically. When it switches over, decelerate immediately (r) to real time.
59. Step deleted. Please move on.
60. Carefully time warp forward until you are approximately 2 or 3 planetary diameters away from
your target (mars). Use mfd graph to estimate. Do not time accelerate beyond 1000x or you risk
an overshoot.
61. Step was deleted. Please move on.
62. Set your left mfd 'view' to 'maneuver' (shift + w).
62.5 Ensure that your 'min alt' (read from right mfd) is still between 200k and 250k. If it has
moved, point prograde ([) and fire linear thrusters as needed to adjust minimum altitude.
63. In left mfd change variable to 'maneuver mode' (shift + >). Turn 'maneuver mode' to 'on'
(shift + '+')
We will now adjust variables to create a hypothetical insertion.
64. In left mfd change variable to 'man.date' (shift + >). Adjust with (shift + '-') until value of 'H. Pe
MJD' matches the value of Pe MJD. Use (shift +{) to adjust sensitivity and fine tune.
If things get way out of whack don't worry. All you are doing is creating a plan. Nothing changes
until you actually make a burn. If your plan gets messed up beyond saving, simply change variable
to 'maneuver' (shift + >) and turn the maneuver mode 'off' (shift + '+'). Then turn it back on again.
Now everything has been reset. Jump back to step 64 and carry on. No worries.
Once you get 'H. Pe MJD' and 'Pe MJD' to match MAKE NO FURTHER ADJUSTMENTS to the 'man.
date' variable.
Note: It is important that the date be adjusted BEFORE any prograde velocity is adjusted. In some
rare cases doing them the other way around may cause a lock-up of the transx. If a lock-up does
occur, turn the maneuver mode off and on again to reset. Go Here to read Rob's feedback about
the lock-up issue.
65. In left mfd change variable to 'prograde vel' (shift + >). Use (shift + '+') and (shift + '-') to bend
the hypothetical orbit (dotted yellow line) around target body (mars). Use (shift +{) to adjust
sensitivity and fine tune. See graphic below.
66. This step was deleted. Please move on.
67. In left mfd adjust variables 'prograde vel' (to tighten orbit) and 'outward vel' (to match 'H Pe
MJD' to 'Pe MJD'). Adjust with (shift + '+') and (shift + '-') until a fairly tight orbit (dotted yellow)
exists and 'min alt' is between 200k & 250k. Use (shift +{) to adjust sensitivity and fine tune.
Note: Pump up the sensitivity to 'super' or higher before adjusting these variables. Otherwise you
may jump over the desired values and throw your graph into a mess.
Note: During this step the graph will go wonky and invert. This is a normal reaction as your
hypothetical orbit changes from a solar to a mars centered orbit. Keep applying your variable and
the graph will settle down and be recognizable again.
68. Before moving on to the burn, make sure of the following:
'H. Pe MJD' matches as closely as possible, 'Pe MJD'
'Inc' is at lowest possible value (ideally less than 30 degrees)
'min alt' is between 200k & 250k
Your hypothetical orbit is as tight as possible.
69. In left mfd change 'view' to 'target' (shift + w). Using rotational thrusters, center green 'x' on
graph.
70. Monitor 'begin burn' in left mfd. When it reaches zero, fire engines until actual (solid green)
ellipse lowers to match the hypothetical (yellow dotted) ellipse in right mfd. You can also alternately
monitor 'delta v' on the left mfd to anticipate engine cut off. Fine tune with linear thrusters.
Note: Just as it did in the maneuver mode set up, the graph will go wonky a bit as you go from a
solar to a mars centered orbit. This is a natural reaction to being captured by mar's gravity. Don't
panic. Continue to power thru this visual glitch. The graph will settle down and become
recognizable again.
Note: Remember no acceleration beyond 100x when this close to a planet!
71. Change one of your mfds to the standard 'orbit' mfd. You should be in familiar territory now.
Make appropriate burns to establish an orbit above mar's atmosphere (over 150 km).
72. Pat self on back. You've made it to mars!
==
This checklist can be applied to any planet or asteroid outside of earth's orbit.
It wasn't the most efficient or most elegant trip. But our goal was to get to mars and this checklist
should have accomplished that. Use this experience to research and refine your interplanetary
navigational skills.
thanks to Duncan for this excellent navigational tool. As always, where would we be without Martin?
He has made the world a better place.
This checklist is aimed at beginners. I don't claim to be an expert. All I'm saying is that the
following procedure gets me to mars. This checklist is based on the tutorials and manual posted
on Duncan's site. I've filled in some of the holes with a more detailed checklist based on my limited
experiences. Admittedly, this checklist wanders so please take it with a grain. Experienced
navigators can provide corrections where I've strayed or fallen short. Everyone is welcome to
add/comment. I will post all relevant feedback.
I apologize in advance for all type-Os, spelling and usage errors. My writing sux but I think the
points get across to the reader.
This checklist assumes familiarity with the basics of orbital mechanics. If you haven't docked with
the ISS a couple times, then much of this won't make sense. Go here for my rendezvous/docking
checklist.
Here we go!
==
Make sure you've turned fuel consumption off in the launch pad or are flying a ship with low fuel
consumption characteristics. I used the Event Horizon by Brainstorm which is an excellent ship to
use for learning interplanetary travel. It is very responsive in both linear and rotational thrusters for
such a large ship. Make sure that the ship you choose is fully functional with both rotational and
linear thrusters.
Go here for a procedure to check that your ship does not have spaces in its name. You will not be
able to save your TransX work to scenarios that have ships with spaces in their name.
1. After launching Orbiter, switch to cockpit view (F1) and launch the transx mfd (shift + j)
2. Ensure that 'view' is set to 'setup'. If it is not, cycle through view settings (shift + w) until 'setup'
is selected.
Note: Most variables in the transx are selected by cycling through a list of available settings. Each
list is of different lengths so the instruction of "(shift + w)" means "cycle through the list using 'shift +
w' until the appropriate value is selected." This will clean up the checklist by excluding instructions
of "do this twice" or "cycle until" etc. etc. Yer just gonna have to pay attention! :)
3. Change 'select target' to 'escape' (shift + '+') [which means hold down the shift key and hit the
'+' key until 'escape' is selected.]
4. Create a new stage (shift + f)
5. Select target planet 'mars' (shift + '+'). The inside blue circle is earth's orbit. The outside blue
circle is mar's orbit. The sun is the "+" at the center. Where the straight lines intersect the circles
shows you where each planet is on their orbit.
6. Change 'view' to 'eject plan' (shift + w)
7. Select 'prograde vel' variable (shift + >)
8. Increase the value of 'prograde vel' (shift + '+') to see the hypothetical orbit that this thrust
would create. Continue to add thrust until the dashed orbit moves out from the earth and
intersects with mar's orbit (the outside blue circle). The most efficient trip will be one where the
orbit of your ship just barely reaches the orbit of Mars (meaning it reaches mar's orbit but does not
overshoot). If you overshoot, (shift + '-') will decrease thrust.
9. Change variable to 'eject date' (shift + >)
10. Change the date by moving FORWARD (shift + '+') until the two straight dotted yellow lines
match up or get very close to each other. You must move forward since you are trying to
determine what your launch window will be in the future. As the date is adjusted, the dashed lines
might be coming together nicely and then they suddenly jump to totally new positions. Orbital
mechanics are finicky and sometimes they just can't work out for a given situation. Don't worry!
Keep moving the date forward in time and eventually the lines will coincide.
Note: Planetary orbits are ellipses and usually offset from each other. So as you rotate the date,
you might find that the hypothetical orbit (green dashed line) that previously reached out to Mar's
orbit now falls short or maybe overshoots a bit. If this happens, jump back to step 7 and add or
subtract thrust until the ship's orbit is tangential to mar's orbit again.
During many steps of this process of getting to mars, it will be necessary to jump back and forth
between steps to fine tune the plan. Changing one variable may throw an old variable out of whack
so you have to go back and adjust.
11. Using (shift + >), hop between and adjust the variables 'prograde vel','eject date', 'ch plane'
and 'outward vel' until 'cl. App' (closest approach) is as small a value as possible. Use (shift + '+')
& (shift + '-') to adjust each variable.
Note:
k = km
m = 1000km
g = 1,000,000km
t = 1 billionkm
Use (shift +{) to pump up the sensitivity of each variable. This will allow you to fine tune your
approach in smaller increments.
The levels of sensitivity are:
course
medium
fine
super
ultra
hyper
NOTE: Don't labor too much on reducing your approach. At least one correction burn will be
required on the way to mars and variances can be corrected then. Anything below 50k is sufficient
for now.
12. Once you are satisfied that 'Cl. App' is as low as you are willing to get it, switch variable to
"eject date' (shift + >) and write down the MJD.
13. Return to stage one (shift + r). You should now see a graph of the earth with the hypothetical
orbit represented as a curved dashed line.
14. Change 'view' to 'escape plan' (shift + w)
15. Change 'variable' to 'pe distance' (shift + >). This is where you set the distance of the
periapsis above the earth. Add or subtract (shift + '+' OR shift + '-') until 'pe distance' is 6.505.
Fine tune as needed (shift + {). Here are a couple graphs that may help.
Note: I've deviated a bit here from other checklists and hopefully some of you vets can clarify. The
tutorial on Duncan's site calls for a periapsis much lower than this. When I tried it, I crashed and I
think it was because of atmospheric drag. I read someplace (or was told) that earth's atmosphere
ends at 134km. If this is added to the earth base distance of 6371, the periapsis would be 6505.
Right or wrong, let's proceed with 6505 as our chosen distance. I'm guessing that it may not matter
exactly what value periapsis is set at since the transx will adjust for whatever you select. The idea
is get as low as possible for your burn. This will put you at maximum velocity and every km/h helps.
=
Congratulations! You've identified and recorded your launch window! You have also set up your
flight plan in the transx mfd.
Now all we have to do is follow through on that plan.
=
We will now time warp to one day before burn.
Note: Go here to see Rob's alternative to steps 16 - 21. I tried to advance time in the Scenario
Editor but it caused a lock up for me. You may have better luck.
16. Exit Orbiter and 'save current' as E2M01.
17. This step is weird but hang with it: Launch the scenario that you just created (E2M01) in
Orbiter. Quit out and save AGAIN as E2M02. What is this all about?
18. Close out launch pad. Navigate your files and find E2M02 where it lives on your computer.
For most of us that will be:
start/my computer/local Disc C/Program Files/Orbiter/Scenarios
Your computer may have a different file structure. If you can't find the file, do a search.
19. Dbl click on E2M02. It should open in notepad. If it doesn't, close out, launch notepad and
then open the file E2M02.
20. Close to the top of this document, you will see the line "Date MJD #####.#######". Change
the MJD to one day BEFORE the launch window that you copied down in step 15.
Example:
If you wrote down 52799.3435
Change MJD to 52798.3435
21. Save this document using 'file' and 'save'. Do not rename it. Save it as the name it currently
has which should be E2M02. Exit Notepad.
What did we just do and why?
22. Launch E2M02 in Orbiter. You are now exactly one day away from optimum ejection burn.
There are a few things left to do before we make our burn to mars so get your ship up and in orbit
asap. An orbit around 7000 with a low eccentricity will do nicely for now.
We are taking liberties that won't work when flying a 'real' ship with limited fuel. There are ways to
optimize takeoff and align with the target at the same time. However, for simplicity, this checklist will
break these actions into separate steps. After you've gone to mars a couple times with this
checklist, you can research and experiment with ways to maximize efficiency.
23. In your left MFD, change 'view' to 'escape plan' (shift +w). Change 'variable' to 'ej orient'
(shift + >). The solid green straight line is your ship. The grey straight line shows the points where
your current orbital plane intersects the orbital plane of your target (mars).
You will use this information in the next step as you would with the standard 'Align Orbital Plane'
mfd to align your orbital plane with mars' orbital plane.
24. This step was integrated into step 23. Please move on.
25. Rotate your ship to '+normal' and time a burn to straddle either point where the grey line
intersects your orbit. The goal is to reduce 'Rel Inc' to a value as close to zero as possible.
If 'Rel Inc.' increases when you hit the gas, switch quickly to a retro thrusters.
Note: Unlike the standard 'Align Orbital Plane' mfd, the duration and timing of the alignment burn
are not computed for you. Use what you have learned about the 'Align Orbital Plane' mfd to make
your best guess about when to initiate this burn. It will probably take 2 or more burns using steps
23-25. Continue making burns until 'Rel Inc.' is as close to zero as possible.
Note: The open diamond on the grey line is the descending node (DN) if approaching it, use your
normal ( [ ) attitude for burn. The closed diamond is the ascending node (AN) if approaching it,
use your anti-normal ( ] ) attitude for burn.
26. Rotate your orbit so that your periapsis matches the hypothetical periapsis (green dotted
straight line) on the transx graph. How do I do this?
Still confused? Check out this graphic, it may help
After you have eyeballed this alignment, set your right mfd to 'orbit'. At a point halfway between
your apoapsis and periapsis, point ship prograde, use linear thrusters (num pad 6 & 9) to match
the 'T to Pe' from the Transx with the 'PeT' from the 'orbit' mfd. This takes some patience as you
are shooting at a moving target.
27. Set your right mfd to 'orbital' (shift + o). The next time you reach apoapsis, execute the
necessary burn to move your periapsis to the predetermined altitude of 6505.
Note: It is very important that all remaining burns in earth orbit happen as close as possible to
apoapsis and periapsis. To burn at any other point will tend to undo the periapsis alignment that
we just made in step 28.
28. The next time you reach periapsis you may want to execute a burn to move your apoapsis to
an altitude of approx 6600. Ensure your apoapsis doesn't dip below 6505 or it will flip with your
periapsis and cause confusion.
29. Check again that 'T to Pe' from the Transx matches 'PeT' from the 'orbit' mfd. They may have
become dis-aligned on subsequent burns since step 26. Small variances can be ignored but if
they are off substantially, go back to step 28 and line up your periapsis again.
30. Exit Orbiter and 'save current' as E2M03. It is a good idea to save at this point in case
something goes wrong with the burn. Should things go wrong, you can go back and relaunch from
this point.
31. Launch your newly saved scenario (E2M03). Ensure ship is oriented to 'prograde' ([). Set
your right mfd to transx (shift + j) but advance it to stage 2 (r shift + f) while leaving the left mfd in
stage 1. Ensure 'view' is set to 'escape plan' in left mfd (l shift +w). Monitor 'T to Pe' on left mfd.
This is the countdown to burn. When this countdown reaches 30 seconds, (at the appropriate
MJD that you wrote down in step 15) initiate ejection burn. This will be a long burn. While you are
depressing the '+' key on the number pad, hit the left 'ctrl' key and release both. Your main
engines should now remain at full thrust.
Note: (num pad *) will kill main engine burn.
32. As you burn, monitor 'T to Pe' on the TransX mfd. When it reaches zero, use the 'num pad 5'
key to kill rotation. You no longer want the thrusters to adjust for prograde.
33. Continue to burn while monitoring 'DeltaV' in the left transx mfd. Burn until this value is as
close to zero as possible. You can alternately watch the right mfd and see the actual orbit (solid
green) expanding outward from earth orbit (blue) towards the hypothetical orbit (dashed green).
This will help you anticipate when to shut down the main engine burn and fine tune it with linear
thrusters.
34. When 'DeltaV' is zero, or as close as you are willing to get it, shut down all engines. You are
now on the way to mars.
35. Pick a port with the best view of earth. Crack open a cold one and enjoy the view as you leave
earth behind.
==
Now is a good time to discuss time acceleration. Interplanetary travel takes weeks, months, even
years depending on where you go. You will want to use time acceleration to get thru the boring
parts. Time acceleration is accomplished with the 't' and 'r' keys. IT IS IMPORTANT that you do
NOT accelerate time beyond 100x while close to space bodies. If you do, you can put your ship
into an uncontrollable spin. Wait until you are several diameters ( 5 - 6 ) away from a space body
before accelerating beyond 100x.
ALSO
While you are accelerated beyond 100x it is imperative that NO ENGINES OR THRUSTERS ARE
FIRING. This includes prograde, retrograde or normal/anti normal attitude controls. Failure to
ensure all thrust is at zero can put you into uncontrollable spins and/or foul up your flight plan. Be
aware: Uncontrolled spins can destroy marriages, cause you to throw your joystick and tempt you
to kick the dog/cat/hamster. Avoid a spin at all costs.
It is advisable to turn off the rcs (shift + num pad /) when not in use. This helps eliminate accidental
bumps from the joystick.
Until you get the hang of it, I advise saving before you accelerate time.
36. Keep an eye on the left transx mfd. When you have escaped the earth's influence, it will
change automatically to stage 2. At this point, we will make our first correction burn.
NOTE: We will make a burn now but in reality you would wait until you are further away from
periapsis. When possible, burns should be made as close to apoapsis as possible. This will save
fuel because a ship closer to apoapsis is moving slower. The lower your velocity the lower your
mass. It is far easier to adjust the motion path of a lower velocity ship, hence the fuel savings.
Because we have unlimited fuel, we will break this general rule and make a correction burn now.
NOTE: Many orbinauts employ the "1/2" rule. They make a correction every time they travel half
the remaining distance to their target.
37. Because both mfds are now showing the same info, you can power down the right mfd.
38. Switch 'view' to 'manoeuvre' (shift + w)
39. Change variable to 'maneuver mode' (shift + >)
40. turn 'manoeuvre mode' 'on' (shift + '+')
41. Using the variables (prograde vel, outward vel, & ch plane). Adjust each to bring 'cl. app' to
smallest value. (Shift + '+' OR Shift + '-') as needed.
(Shift + {) will adjust the sensitivity of these variables for fine tuning.
42. When cl. App is lowest possible value, switch 'view' to 'target' (Shift + w). We will now burn our
engines according to the hypothetical info we just discovered in step 41.
43. Rotate ship until the "x" centers in the graph.
44. Fire engines until 'Delta V' is as close to zero as possible. Use linear thrusters to reduce 'Delta
V' as low as possible.
45. Change view to 'manoeuvre' (shift + w). Change variable to 'manoeuvre mode' (shift + >).
Turn 'manoeuvre mode' off (shift + '+').
Important note: The 'manoeuvre mode' must be turned off when it isn't being used to
perform a correction burn. If you don't reset the mode between burns, you'll be planning your burn
using old information.
46. As you progress to mars, small course corrections can be accomplished with linear thrusters.
Point ship to prograde ( [ ). Fire linear thrusters as needed to reduce 'Cl App' (closest approach)
to its lowest value.
Note: After long periods of time acceleration, these small corrections may become ineffective. If
so, go through steps 38-44.5 to perform a major correction burn.
47. Make corrections (using steps 38 - 44.5 or step 45) as desired to keep 'cl. App' as low as
possible.
48. Break out the chess board--it will be a long trip.
49. Monitor your progress:
Set one of your mfds to transx (Shift + J)
The inside blue circle is earth's orbit. The solid blue line shows where earth is on that orbit.
The outside blue circle is mar's orbit. The solid blue line shows where mars is on that orbit.
The solid green ellipse is your ship's orbit. The solid green line shows where your ship is on that
orbit.
The grey line indicates the point of intercept as computed by all your actions up to this time using
the transx mfd.
Be patient. Continue to correct your course as desired and wait for the intercept point. Once you
can see mars, you will be tempted to point your nose at it and try to 'rocket' on over. This might
work when approaching the ISS but taking this action on a planetary scale will get you lost in space.
Distance and direction are deceptive in space. Don't trust your eyes, trust your flight plan.
==
There are no easy answers or exact step-by-step for the remainder of your mission. It is best
described as tweaking variables in the maneuver mode to create a hypothetical capture/insertion
and then following through on that plan. This requires a lot of jumping back and forth between
variables and playing with the sensitivity (shift + {). If you have the sensitivity set too low, you can
often jump across the desired value which produces quite a bit of tail chasing. It will take some
experience for you to become comfortable. Take your time and pay strict attention to what you are
doing. Learn a little each time and soon it will be almost second nature.
In this set up burn, your main concerns will be to set your minimum altitude and reduce your
inclination as much as possible.
50. Time accelerate ( 't' key ) until the green line (your ship) almost coincides with the grey line
(intercept point) then return to time normal ( 'r' key ).
51. Power up the right mfd as transx. Advance to stage two (shift + f). Change 'view' to
'Encounter' (shift + w). Minimum altitude (Min Alt) and inclination (inc) can be read from the right
mfd. If your current trajectory will cause an impact with your target, you will see surface
coordinates instead of an altitude reading.
52. Change left mfd to 'View: Maneuver' (shift + w). Change variable to 'maneuver mode' (shift +
>) and turn maneuver mode to 'on' (shift + '+')
52.5 For this step we want to avoid using the 'man. date' variable. We are getting very close to
our insertion burn and if we advance the maneuver date too far into the future it will exceed the
insertion point.
53. Using the 'prograde vel', 'outward vel' and 'ch plane' variables, tweak with (shift + '-') or (shift +
'+') to set 'min alt' between 200k and 250k (read from right mfd) and to get 'Inc' down to its lowest
value. Use (shift +{) to adjust increment sensitivity and fine tune. Lots of patience here!
Note: In general, the lower the better but getting your Inc below 30 degrees is good enough.
54. Step deleted. Please move on.
55. Change 'view' on left mfd to 'target' (shift + w). Use rotational thrusters to center the green 'x'
on the graph. Fire engine until 'Delta V' is reduced to lowest possible value. Use linear thrusters
to fine tune.
56. Change 'view' to 'maneuver' (shift + w). Change variable to 'maneuver mode' (shift + >). Turn
maneuver mode 'off' (shift + '+').
You have now established a low pass on your target (mars) at the smallest inclination.
==
Again, no easy answers or exact step-by-step to be had. Pay strict attention to your readouts as
you adjust your variables. Pump up sensitivities early to avoid jumping over desired values.
The basic goals when setting up insertion are:
Minimum altitude between 200k & 250K
Inclination is at its lowest possible value (ideally less than 30 degrees)
'H Pe MJD' matches 'Pe MJD'
Work to get the tightest orbit possible
57. If both mfds are not on, power them both up. Advance right mfd to 'encounter' (shift + f).
NOTE: Be careful with your acceleration. You are used to accelerating to pretty high multiples due
to your long voyage but now you are getting back to coping with your trip on a planetary level. You
should not accelerate beyond 10,000 from this point on. If you do, you may find that you pass
mars or get way too close before you have time to decelerate.
58. Time accelerate (t) until the left mfd switches over to 'encounter'. This will happen
automatically. When it switches over, decelerate immediately (r) to real time.
59. Step deleted. Please move on.
60. Carefully time warp forward until you are approximately 2 or 3 planetary diameters away from
your target (mars). Use mfd graph to estimate. Do not time accelerate beyond 1000x or you risk
an overshoot.
61. Step was deleted. Please move on.
62. Set your left mfd 'view' to 'maneuver' (shift + w).
62.5 Ensure that your 'min alt' (read from right mfd) is still between 200k and 250k. If it has
moved, point prograde ([) and fire linear thrusters as needed to adjust minimum altitude.
63. In left mfd change variable to 'maneuver mode' (shift + >). Turn 'maneuver mode' to 'on'
(shift + '+')
We will now adjust variables to create a hypothetical insertion.
64. In left mfd change variable to 'man.date' (shift + >). Adjust with (shift + '-') until value of 'H. Pe
MJD' matches the value of Pe MJD. Use (shift +{) to adjust sensitivity and fine tune.
If things get way out of whack don't worry. All you are doing is creating a plan. Nothing changes
until you actually make a burn. If your plan gets messed up beyond saving, simply change variable
to 'maneuver' (shift + >) and turn the maneuver mode 'off' (shift + '+'). Then turn it back on again.
Now everything has been reset. Jump back to step 64 and carry on. No worries.
Once you get 'H. Pe MJD' and 'Pe MJD' to match MAKE NO FURTHER ADJUSTMENTS to the 'man.
date' variable.
Note: It is important that the date be adjusted BEFORE any prograde velocity is adjusted. In some
rare cases doing them the other way around may cause a lock-up of the transx. If a lock-up does
occur, turn the maneuver mode off and on again to reset. Go Here to read Rob's feedback about
the lock-up issue.
65. In left mfd change variable to 'prograde vel' (shift + >). Use (shift + '+') and (shift + '-') to bend
the hypothetical orbit (dotted yellow line) around target body (mars). Use (shift +{) to adjust
sensitivity and fine tune. See graphic below.
66. This step was deleted. Please move on.
67. In left mfd adjust variables 'prograde vel' (to tighten orbit) and 'outward vel' (to match 'H Pe
MJD' to 'Pe MJD'). Adjust with (shift + '+') and (shift + '-') until a fairly tight orbit (dotted yellow)
exists and 'min alt' is between 200k & 250k. Use (shift +{) to adjust sensitivity and fine tune.
Note: Pump up the sensitivity to 'super' or higher before adjusting these variables. Otherwise you
may jump over the desired values and throw your graph into a mess.
Note: During this step the graph will go wonky and invert. This is a normal reaction as your
hypothetical orbit changes from a solar to a mars centered orbit. Keep applying your variable and
the graph will settle down and be recognizable again.
68. Before moving on to the burn, make sure of the following:
'H. Pe MJD' matches as closely as possible, 'Pe MJD'
'Inc' is at lowest possible value (ideally less than 30 degrees)
'min alt' is between 200k & 250k
Your hypothetical orbit is as tight as possible.
69. In left mfd change 'view' to 'target' (shift + w). Using rotational thrusters, center green 'x' on
graph.
70. Monitor 'begin burn' in left mfd. When it reaches zero, fire engines until actual (solid green)
ellipse lowers to match the hypothetical (yellow dotted) ellipse in right mfd. You can also alternately
monitor 'delta v' on the left mfd to anticipate engine cut off. Fine tune with linear thrusters.
Note: Just as it did in the maneuver mode set up, the graph will go wonky a bit as you go from a
solar to a mars centered orbit. This is a natural reaction to being captured by mar's gravity. Don't
panic. Continue to power thru this visual glitch. The graph will settle down and become
recognizable again.
Note: Remember no acceleration beyond 100x when this close to a planet!
71. Change one of your mfds to the standard 'orbit' mfd. You should be in familiar territory now.
Make appropriate burns to establish an orbit above mar's atmosphere (over 150 km).
72. Pat self on back. You've made it to mars!
==
This checklist can be applied to any planet or asteroid outside of earth's orbit.
It wasn't the most efficient or most elegant trip. But our goal was to get to mars and this checklist
should have accomplished that. Use this experience to research and refine your interplanetary
navigational skills.
Go here to see the old checklist
SET UP FLIGHT PLAN
EJECTION
COURSE CORRECTION
CORRECTION FOR INTERCEPT
INSERTION BURN
The Event Horizon performs an insertion burn at Mars
