Lunar Reconnaissance Orbiter (BrianJ add-on)

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Overview

The Lunar Reconnaissance Orbiter (LRO) is the first mission in NASA's planned return to the moon. LRO will launch 2nd March, 2009, with the objectives to finding safe landing sites, locate potential resources, characterize the radiation environment and test new technology.

The return to the moon will enable the pursuit of scientific activities that address our fundamental questions about the history of Earth, the solar system and the universe -- and about our place in them. It will allow us to test technologies, systems, flight operation and exploration techniques to reduce the risk and increase the productivity of future missions to Mars and beyond. It will also expand Earth's economic sphere to conduct lunar activities with benefits to life on our home planet.

LRO is an unmanned mission to create the comprehensive atlas of the moon's features and resources necessary to design and build a lunar outpost. LRO focuses on the selection of safe landing sites, identification of lunar resources and the study of how lunar radiation will affect humans.

After launch, the LCROSS shepherding spacecraft and the Atlas V’s Centaur upper stage rocket will execute a fly-by of the moon and enter into an elongated Earth orbit to position LCROSS for impact on a lunar pole. On final approach, the shepherding spacecraft and Centaur will separate. The Centaur will act as a heavy impactor to create a debris plume that will rise above the lunar surface. Following four minutes behind, the shepherding spacecraft will fly through the debris plume, collecting and relaying data back to Earth before impacting the lunar surface and creating a second debris plume.

The debris plumes are expected to be visible from Earth- and space-based telescopes 10-to-12 inches and larger.

This is a difficult and challenging mission. Experienced orbinauts will enjoy the challenge of targeting the LCROSS to impact the North Pole of the moon, when the LRO spacecraft is overhead. This mission is not recommended for people recently starting to use Orbiter. Familiarity with setting up gravity assist maneuvers in TransX is a required skill.

Mission Objectives

LRO

The objective of the LRO mission is to map the lunar surface in preparation for the return of human missions to the moon, which are planned to occur by 2020.

LCROSS

Earth’s closest neighbor is holding a secret. In 1999, hints of that secret were revealed in the form of concentrated hydrogen signatures detected in permanently shadowed craters at the lunar poles by NASA’s Lunar Prospector. These readings may be an indication of lunar water and could have far-reaching implications as humans expand exploration past low-Earth orbit. The Lunar CRater Observing and Sensing Satellite (LCROSS) mission is seeking a definitive answer.

required add-ons

optional add-ons

Procedures

Accuracy of burns in this mission is CRITICAL. During this mission, especially after the TLI burn, we will be using the tools TransX or IMFD to get the DIRECTION of our burns, and using IMFD map to monitor in real time the MAGNITUDE of the DeltaV we are imparting. For this mission, usually the AUTOBURN button is NOT your friend.

You may wish to edit your config/Moon.cfg file and change the LAN line to 

LAN = 2.2483                     ; ascending node of equator - CHECK!

This will ensure a more accurate simulation.

Launch

Fire up the 01 - AV020 LRO launch scenario in the LRO scenarios folder This is a night launch so visibility is poor until after the TLI burn. The scenario starts at UTC 03/02/2009 05:25:00. Launch time is UTC 05:26:27. The default camera view is Ground Observer. You have just over a minute to set up the camera to your personal preference. 

At UTC 05:26:17 press the p key to start the launch countdown and 1st stage auto-pilot.

At T-5 seconds, engine ignition will happen, and the hold down clamps release at T-0. The Atlas V-401 1st stage autopilot will continue until 1st stage seperation.It can be disengaged by Pressing p again, but this is not recommended. 

10 seconds after 1st stage separation, press the p key again.

This will ignite the 2nd stage Centaur engine, and engage the 2nd stage autopilot which will put the vehicle in a circular 185km parking orbit. Pressing p again will disengage the 2nd stage autopilot.

Shortly after 2nd stage ignition, the fairing will be automatically jettisoned, and the LRO/LCROSS spacecraft will be exposed.

TLI

After SECO, while established in the 185km parking orbit, set the Left MFD to IMFD. 

Also, click the HUD button in the right orbit MFD so that your HUD is set to orbit reference Earth

IMFD Configuration set-up

Click MNU, then Configuration. 
Click Nxt, then + to change the Mission timer to MJD mode. 
Click Nxt ten times to hightlight Parking Orbit Alt. 
Click Set, and set this to 185k

Establishing the TLI burn

Click MNU, then Course.
Target Intercept should be highlighted. If not, click Nxt until it is.
Click Set
Click Tgt and enter Moon
Click Nxt so that the Tej parameter is highlighbted.
Click + or - repeately until the dV parameter reaches a minimum. This should be about 3.13k
Click Pg, then BV, then AB

Sit back and wait for the burn. You may wish to use time acceleration to get close to the burn time, but set it back to 1x acceleration once you get close.

Note for Brian: It may be possible to use an offset in IMFD to target a polar orbit in the TLI. I think AMSO does something like this. It might be worth checking out, but it may make the LCROSS targeting harder. 

When the TLI burn is complete, click on the BV button to restore the main IMFD Course target intercept screen

Do not jettison LRO yet

Lunar targeting/LRO

When you reach 32M altitude above the Earth, the Centaur engine will automatically purge of all fuel and control switches over to the LCROSS propulsion system. You may initate the engine purge manually by pressing B. It is critical that you get your targeting done for both LRO and LCROSS before this time, as once that happens, your deltaV budget is severely limited.

At about 21M altitude above the earth, select TransX in the Right MFD. 

Click on the -- button until the target is Moon
Click VW once so the View is Manoevre

Select TransX also in the Left MFD. 

In the Left MFD click FWD, then VW, so that the view is 'Encounter'
In the Right MFD click ++ so Manoevre mode is On
Click VAR 5 times so that Ch. Plane vel. is displayed
Click ADJ so that Medium adjustment mode is entered.
Click -- until the Min Alt. parameter in the Left MFD is over 216k

Our goal here is to end up with an Inclination parameter in the left MFD as close as possible to 90 degrees, and the Min Alt. parameter as close as possible to 216k. 

In the Right MFD click VAR 3 times so that Prograde Vel is selected.
Click on ADJ 3 times  for Super adjustment mode.
Click on ++ or -- until Min Alt. is close to 216k and Inclination is close to 90 degrees in the Left MFD.

Keep repeating these adjustments, using finer adjustment modes until you get as close as possible to the required parameters. Work quickly though, as the orbital debris is getting closer and we still have to target the LCROSS spacecraft. 

In the Right MFD click VW to get Target view
Use rotation mode to get the cross as close as possible to the center of the target. 
Do NOT make the burn yet

Use the planetarium view F9 key to make sure you are pointed in a generally northerly direction (towards Polaris + or - 30 degrees or so) If you are pointed in a southerly direction, the transx targeting will have to be re-done using ++ Ch. plane vel. instead of --

Set the Left MFD to IMFD. 

Press the MNU button and select Map mode.
Press the TGT button and enter Moon
Press the Sel button until Ref Moon is displayed.

Watch the PeA parameter as you make a low dV burn with the Centaur engine Ctrl-numpad + When the Pea gets to +216k, STOP the burn with the numpad * key. As it gets close you may with to use translation mode and the numpad-6 key. There is no reverse translation. Don't overshoot by very much, if at all. Some dV will be added by LRO jettison which we will have to correct later. 

Press the j key to jettison LRO.

On the Right MFD click VW twice to get back to Maneuver view
Click VAR until Maneuver Mode is displayed.
Click ++ to turn Maneuver mode Off

Lunar targeting/LCROSS

  • Swingby of moon is passive (no thrusting)
  • 81 days in post-swingby cruise orbit
  • Current baseline is 3-month trajectory with south pole impact
  • Two revolutions in high ecliptic inclination (~50 deg), 40-day period Earth orbit


After the LRO is jettisoned, swing the Centaur around 180 degrees. Use the finely graduated scale on the hud, or Attitude MFD to do this. When the Centaur is pointed 180 degrees from where it was when you made the LRO targeting burn, make another small burn, again watching IMFD map so that the final PeA is about 2M on the opposite side of the moon. Select IMFD on the right MFD 

Click MNU, then Course. Click NXT 4 times so that Delta Velocity is highlighted. Click Set.
Click on TGT and enter Moon as the target. Click Nxt 5 times so that dVf is highlighted. 
Click Set and enter 0.

In the Left MFD click PG then Plan. The green line of our orbit should turn blue. 
In the Right MFD click + repeatedly. The RIn parameter in the Left MFD should increase. If not, Click - until it does.
Also watch the PeA parameter. Do not let it go negative. 

When PeA gets too low, click Nxt on the Right MFD so that dVp is highlighted. 
Click - until PeA in the Left MFD is back to around 2M. Setting Adj to 10x may be necessary, but return it to 1x when finished.

Keep repeating these adjustments until Rin is close to 90 degrees and PeA is close to 2M. This is just a ball bark "rough in" to make our transx tageting easier. The numbers do not have to be exact. Work quickly though. Liberal use of the Pause function is encouraged. 

In the Right MFD, click Pg, then BV.

Use rotation mode to align the cross in the center of the target and then select translation mode and use CTRL-numpad + to burn until BT is close to 0. AutoBurn is not recommended. 

Once this is done, in the Left MFD click PG, then Plan, so the orbit line turns green again.

Select Transx in both MFD's.Select moon as the target in the right MFD, as in the LRO targeting. 

Click the FWD button for stage 2, make sure the view is Setup and select the target as Escape.
Click the FWD button again for stage 3, and select the target as Moon
Click the VW button for Sling Direct view.
On the Left MFD, click the FWD button for stage 2, if not already there. 
Click the VW button for slingshot view, if not already there.

There will be a green line extending from the center of the moon to hopefully past the edge. This is an edge-on view of our current approach to the moon. We need to fine tune this approach to give us a lunar gravity assist which will result in a highly inclined orbit around the earth with a period of 40 days 

On the Right MFD, click the VAR button twice to bring up the Inc. angle parameter
Click on -- several times until the dotted yellow orbit is about the same size as the solid green line. 
It does not have to be superimposed in the same place, but of a similar diameter.

On the Left MFD the dotted yellow line should be on the same side (more or less) of the moon as the green line. If it is on the opposite side, click on the ++ button until it is on the same side. 

On the Right MFD, click on VAR four times until the outward angle parameter is shown.
Adjust this parameter, and the Inc. angle parameter until the dotted line is superimposed on the solid green line in the slingshot view.

This is our current trajectory. Now we need to adjust the trajectory to impact the moon in 2 orbits with a 40 day period. 

On the Right MFD, click VW so that the setup view is shown
Click VAR 3 times so that Orbits to Icept is shown
Click ++ 4 times so that the Orbits to Icept parameter is 2.0

Now we must figure out what our Enc. MJD should be. Take the current MJD and add 85 to it. (5 days to reach the moon, then 2 orbits of 40 days each.) For the Feb 28 (UTC) launch this would be 54890 + 85 = 54975. This is the Enc. MJD we will be shooting for. 

Click VW again in the right MFD to get back to sling direct view.
Adjust the Inc Angle to get as close as possible to the desired MJD.
Click VAR so that Outward angle is displayed. 
Click ADJ twice so that the increment is Fine 
Adjust Outward angle to get the Cl. App. as close as possible.

My current solution is Inc Angle of -115.18 degrees and Outward angle of -47.54. Enc MJD is 54978.5013, and Cl. App is 1.747M
Your Mileage may vary. 

Once a solution has been reached, click BCK twice on the Right MFD. The View should be Maneuver and Maneuver mode should
be off. Click ++ to turn Maneuver mode on
Adjust Prograde Vel. and Ch. Plane vel. until the dotted yellow line on the Left MFD lines up with the solid green line. 
R. Inc should be as close as possible to 0, and Pe Ratio should be as close as possible to 1.000.
Once this is done, click VW in the right MFD to get to target view.
Use rotational thrusters to get the cross in the middle of the target and burn until Rel.V is as close to 0 as possible.
Click VW twice to get to maneuver view, Click VAR to get to Maneuver mode and turn it off.
Look at the Left MFD to see how you did. Additional corrections may be done as you get closer to the moon.

LRO_part_2

Mid course correction/LRO

Switch focus back to LRO. 

Press the k key to deploy the LRO solar panels
Once the panels have fully unfolded, and rotated to face the sun,
press the g key to deploy the antenna

In the Left MFD select IMFD, click on MNU and select Map.
Make sure TgT is Moon, and click Sel until Ref is Moon.

Wait until PeT is about 350k
Select IMFD in the Right MFD 

Click on MNU, then Course. Click Nxt 4 times until Delta Velocity is highlighted, then click Set.
Click Nxt 5 times until dVf is highlighted, click Set and enter 0.
Click on TgT and enter Moon.
In the Left MFD, click Pg, then Plan so that the green line turns blue.
In the right MFD adjust dVp and dVf so that RIn and PeA in the left MFD are as close as possible to 90 degrees and 216k respectively
When these adjustments are finished, click PG,BV, then AB in the right MFD. 
When the burn completes, click Plan in the left MFD so the blue line returns to green.

Repeat these adjustments as necessary as you get closer to the moon.

Course correction/LCROSS

Switch focus to AV020 Centaur. Select TranxX in both left and right MFDs 

In the right MFD, click ++ to turn Maneuvre mode On.
Adjust Prograde vel and Ch. plane vel so that on the Left MFD R. Inc is as close as possible to 0,
and Pe Ratio is as close as possible to 1.0
Click VW on the right MFD for Target view. Use rotational thrusters to get the cross as close to the
center of the target as possible. Press M to enable the dummy main engine, and use the numpad-+ key to
burn the engine. Reduce the Rel V to as close to 0 as possible. 

As an alternative to using the dummy main engine, after the Centaur is targeted with rotational thrusters, you can 
rotate the Centaur 180 degrees and use the LCROSS main engine numpad-- (minus) This will provide you with graphics
of the engine firing in external view. (F1)

Repeat these adjustments as necessary as you get closer to the moon.

orbit insertion/LRO

The LRO main engine is not strong enough to get it into a circular orbit in one try. It will take 4 burns over 12 orbits to achieve the initial 216km x 30km commissioning orbit, with periselene over the South Pole. The first burn is critical in that we must avoid a situation where we are "weakly captured" or not captured at all. The orbit eccentricity at the end of our first burn must be 0.8 or less.

When LRO's PeT is about 10k, select IMFD in the left MFD, and Orbit MFD in the right. 

Click on the HUD button on the right MFD. In the left MFD click MNU, then Orbital.
Click TgT, then type r.

Note that The burn time to a circular orbit is over 4k seconds (over an hour!). Make sure rotational mode is selected. 

At 2k seconds to PeT, select Retrograde mode on the hud. When retrograde attitude is established, de-select retrograde mode.
Start the engine by pressing numpad-+ and tap the CTRL key to keep it burning.

Notice that the PeA in the right MFD is decreasing. 

Use the numpad 1 and 3 keys to move the attitude closer to what the Orbital IMFD mode thinks it should be until
the PeA starts increasing.

Keep adjusting the attitude between these points to keep the PeA as close as possible to 216km. 

When the ApA. parameter in the Right MFD is 3160km, press the numpad-* key to stop the burn.
The LRO then completes 4 orbits at 3160km x 216km before the next burn,
you can switch focus to AV020Centaur and enjoy the view as it passes by the moon.

After the flyby, switch back to LRO and after 4 orbits, wait until PeT is 800k. Press the retrograde button, and de-select it when retrograde attitude is achieved. 

Follow the procedure above to make the second burn,
keeping PeA as close as possible to 216km, and burn until ApA is 967km.

After another 5 complete orbits at 216km x 967km, make a third burn to circularize your orbit at 216km.

Make a final burn on your next pass over the North Pole to reduce your PeA to 30km near the South Pole.

This is the "frozen" lunar orbit at 216km x 30km, periselene over the South Pole, for the 60-day commissioning phase.

LCROSS orbit correction 1

Switch focus back to AV020Centaur and wait until the orbit is farthest from the moon. WARNING Using High values of time acceleration may cause problems for the LRO orbit. It can even kick it out of lunar orbit. It is best to be patient, and check on LRO's orbit once in a while. If it's orbit changes significantly due to time acceleration, fix it with scenario editor. It is now necessary to tune IMFD map for maximum accuracy. 

Select IMFD in the left MFD. Click MNU, then Map. Click TgT and type Moon, Click Cnt, and type Earth.
Click MOD 3 times. This should give you the Map-config screen. Legs/Frame should be highlighted. Click Set and type 64.
Click Nxt, then - twice. Click Nxt twice again, so that Period limit is highlighted, and click + to turn it off.
Click Nxt and + to turn Hyper limit off. Click Nxt twice and then + so that Tgt weak Pe is set to No.
Click Nxt and + to turn One Pe/Ref off. Click Mod again to return to the map display.

Several orbits should now be shown. Select IMFD in the Right MFD. 

In the right MFD click MNU, then Course. Select Delta Velocity mode, then set the target to Moon. Set the dVf parameter to 0.
In the left MFD click PG, then Plan. in the right MFD, adjust dVf to get the most deflection of the orbit you can when 
LCROSS intersects the moon in 1.5 orbits. When this is done, click on Pg, then BV, then AB.
When the burn is finished, click Plan in the left MFD to turn the orbit line green again.

Alternate procedure

Select transx in the right MFD. 

In the right MFD, select target moon and 1.5 orbits to intercept. Change the view to Maneuver, and select Maneuver mode.
Adjust prograde vel, and Ch. Pl vel for the minimum closest approach. 
Select target view and use rotational mode to align the cross with the target. 
Start the burn and watch the orbit in Map MFD mode in the left MFD. When maximum orbit deflection is reached at the moon intercept point
after 1.5 orbits, stop the burn.

LCROSS final moon targeting

Go around one more orbit of the earth. When we are again at the farthest point in our orbit from the lunar intercept, set IMFD map in the left MFD and IMFD course in the right MFD. 

In the right MFD set target intercept mode. Set target to Moon.
Adjust the TIn MJD and then TIn parameters for minimum Enroute dV. Change Target intercept mode to Delta Velocity mode.
Click Nxt 4 times to highlight Get Burn, and click +.
In the left MFD click Sel until ref is Moon and PeA is the lowest value. Click Pg, then Plan.
In the right MFD adjust the highest value of dVf, dVp, or dVo to minimise PeA in the left MFD.
As the orbit changes, the PeA number may change, so you may have to return to the proper one with the Sel button once in a while
Adjust the next highest value of dVf, dVp, or dVo, and finally adjust remaining value. 
When these adjustments are done, click Pg, BV, and AB.

Note the PeT in the left MFD. We need to make another burn when we are halfway from here to the noon so that we will impact the moon. This will be at about 850k PeT. Repeat the above procedure until PeA is at least -1M, and hopefully as low as you can get it.

LRO Orbit Circularization

60 days after your last LRO orbit insertion burn, switch focus to LRO, and at Perilune over the south pole, burn retrograde until the ApA is 50km.

LCROSS Lunar pole targetinjg

Switch focus back to AV020Centaur. When the PeT is 130k Set IMFD map in the left MFD and IMFD Base approach in the right MFD. 

In the left MFD set target Moon and center to Self (x)
Click on Sel until Ref Moon is displayed with a negative PeA.
In the right MFD click REF, and type Moon. 
Click Nxt until Hint is highlighted. Click Set and type the value shown for PeA in the left MFD.
Click Prv until Lat is highlighted. Click Set and type -89.9
Click Nxt', then Set and set the Alt to 0.
Click Nxt, then Set and set the ReA (Re-enty Angle) to 75
Click Nxt, then Set and set the Ant parameter to 0
You may need to reset the Hint Parameter at this time to the current PeT.
You may also need to tweak the Lon parameter to get the Enroute: dV parameter to display.
Once it is displayed, adjust the ReA parameter to minimize the dV. 
It may take several iterations of adjusting hint, Lon, and ReA to get the dV to a minimum value.
When a minimum dV value has been reached, click PG, BV, and AB.

Repeat the above procedure at Pet of 100k, again at 70k, and once more at 51k PeT.

LCROSS LRO targeting

  • ~7 hours prior to impact, LCROSS will separate from Centaur upper stage and perform a ~4-minute delay maneuver (~23 m/s) to enable LCROSS to fly through Centaur impact plume
In the left MFD, click REF and type Moon, then click TGT and type LRO
Click PRJ until Target is displayed in the lower left corner.
Click Z- until you can see the white dot that represents the current vessel. Remember where this "incoming" leg of the orbit is located.
In the right MFD click MNU, then Course. Highlight Target Intercept, then click Set.
Click TGT, and type LRO. Click PRJ until LRO is shown in the lower left corner of the MFD.

The orientation of the two MFD's should now be exacly alike with repect to the position of the LCROSS and LRO orbits. We want to adjust the time of intercept of the LRO orbit so that it is 4 minutes (240 seconds) before LRO passes by. 

In the right MFD click Nxt until the Tin parameter is highlighted.
Click + or - until the white intercept point line intersects the point where the incoming side of the LCROSS orbit intersects the LRO's orbit.  
Whether you use + or - depends on which has the least dV at the intersect point.
  • current strategy
    • target LRO
    • boost additional 5m/s prograde
    • retarget base approach
    • separation at 25k PeT
    • LCROSS target LRO intersection
    • LCROSS target base approach
    • rinse, repeat

External reference documents

LCROSS Astronomer Workshop
NASA LCROSS page
NASA LRO page
ASU LRO Camera Page
Trajectory Design of the Lunar Impactor Mission Concept
Lunar Reconnaissance Orbiter Spacecraft & Objectives
Mission Design And Operations Considerations For NASA’S LRO
Mission Design for the Lunar Reconnaissance Orbiter

TODO

  • Fix procedure for actual mission parameters
    • updated Launch date? - currently: 2nd March 2009 05:26:27
    • LCROSS North pole impact
      • Target a specific crater
    • Try IMFD slingshot mode to refine flyby once in lunar SOI
  • Add keyboard commands section
  • Convert to .CHM for help mode within orbiter
  • Add images
    • IMFD map periapsis projection to show LCROSS orbit inclination
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