Mike’s Tweets

Calendar

July 2014
M T W T F S S
« Dec    
 123456
78910111213
14151617181920
21222324252627
28293031  

LADEE Trajectory Update 10-9-13: LOI-2 nominal

The LADEE Lunar Orbit Insertion burn 2 (LOI-2) executed as planned this morning at 3:38 PDT, placing LADEE into a 4 hr orbit.  Things move much faster now for the spacecraft, and the Moon is looking a lot bigger. We originally captured with a periselene altitude near 560 km but our periselene has now been lowered to an altitude of ~235 km by Earth perturbations in the Post-LOI-1 24 hr orbit.  The planned periselene of the commissioning orbit was 250 km, however the small (<1%)  underperformance of LOI-1 caused aposelene to be slightly higher, and thus we got slightly more Earth perturbations than we nominally planned for.  The result of this is that we got a bit of free lowering from the Earth, which we’ll take!  (Since we plan to go lower than 250 km anyway).  So the current plan is to drop the aposelene to 250 and perform commissioning there in the 235 x 250 km orbit.

LOI-2 lowered our apogee down to ~2200 (we’ll have to wait for some more tracking to verify that exactly).

From our pre-LOI2 planning, things should now (9 Oct 2013 13:00 UTC)  look like this:

 

ladeeview

 

And we are here in the orbit:

moonview

 

 

If you could see the orbit from Earth you’d see this:

 

earthview

 

  • edgar.kaiser

    Evaluating yesterday’s Doppler inversions I noticed that HORIZON ephmerides are already 20 minutes behind the current trajectory. Will HORIZONS be updated soon?

  • http://www.astrogatorsguild.com/ Astrogator_mike

    We’ll see what we can do. Last I heard the Horizons system was down. The ephem on there is stale though, and I’ll try to get an update.