by Astrogator Mike | Oct 4, 2013 | General Comments
LADEE is rapidly approaching the Moon. Depending on who you talk to, you can consider the spacecraft to be within the “Sphere of Influence” of the Moon somewhere near 66,000 km (on LADEE we switch central bodies on our numerical integrators at 50,000 km, but that’s not a magic number). So we’re not quite Moon-Centered yet, but that doesn’t stop us from giving you pictures in a Moon centered frame.
As you can see, showing the Earth orbit no longer has great utility:
[Note: Velocity is still Earth-relative] I have to still show my favorite view of the phasing loops, the Earth-Moon rotating coordinate frame, but Earth-bound phasing loops are about to be less relevant.
But as much as I like the phasing loops, this is the view we really should be thinking about (and I like it so much I just tweeted it!):
And this view gets me very excited:
But we still can look back to where we came from:
If you check the dates on the pictures, you can see what order I created them in, as the dates don’t all match and I’m animating in real time.
by Astrogator Mike | Oct 1, 2013 | General Comments
LADEE on 10-1-2013 07:13 UTC (Rotating Coordinate Frame)
LADEE on 10-1-2013 07:13 UTC (Earth Inertial Coordinate Frame)
LADEE on 10-1-2013 07:13 UTC (Top View)
LADEE now under the GEO belt, and heading for its last perigee.
by Astrogator Mike | Sep 30, 2013 | General Comments
LADEE on 9-30-2013 18:56 UTC (Rotating Coordinate Frame)
LADEE on 9-30-2013 18:56 UTC (Earth-Centered Inertial Coordinate Frame)
LADEE on 9-30-2013 18:56 UTC (Top View)
Next Maneuver: TCM-1 on 1 Oct. 2013 22:00:00 UTC (11 hrs after Perigee 3).
by Astrogator Mike | Sep 29, 2013 | General Comments
LADEE on 9-29-2013 16:05 UTC (Rotating Coordinate Frame)
LADEE on 9-29-2013 16:05 UTC (Earth-Centered Inertial Frame)
LADEE on 9-29-2013 16:05 UTC (Top View)
by Astrogator Mike | Sep 27, 2013 | General Comments
On Sep. 28 2013 05:33 UTC, LADEE is coming out of its last apogee and at an altitude of 214,000 km.
LADEE on 9-28-2013 5:46 UTC
LADEE on 9-28-2013 5:46 UTC (Top View)
Perigee occurs on 1 Oct near 11:00 UTC. A final small midcourse maneuver will take place at 1 Oct 2013, 22:00 UTC. This 0.9 m/sec maneuver will precisely target insertion parameters for the 6 Oct. 2013 10:57 UTC LOI-1 maneuver. LOI-1 is designed to place the spacecraft into a 24 hr orbit, with a periselene altitude of 590 km [correction: previously I said 750 km, this isn’t quite right. For LADEE we aren’t capturing right at periselene, like orbital mechanics would recommend. Instead we burn off periselene just a bit. We wait until 5 minutes past we come out from behind the Moon, and start our burn. This ends up being roughly 5.5 minutes after periselene. This allows the Deep Space Network to get a lock on us and telemetry to start flowing before the burn starts. So the altitude at the end of this burn is at about 750 km, but the actual periselene altitude is closer to 590 km]. After 3 revolutions in this orbit, 3rd-body Earth gravitational perturbations will have lowered periselene to an altitude of 250 km (by design). At this point, LOI-2 will be performed on 9 Oct 2013 10:37 UTC ( to place LADEE into a 4 hr orbit (also with a 250 km periselene altitude). LADEE will spend 3 days in this orbit until LOI-3 (12 Oct 2013 10:37 UTC), which circularizes the orbit at 250 km. LADEE will spend 30 days in this “commissioning orbit”, and will also perform tests using the laser communications experiment (LLCD). The timing and magnitudes of the maneuvers leading to the commissioning orbit are given below.
LADEE on 9-28-2013 5:48 (Earth-Moon rotating frame)
Executed Maneuvers:
AM1 11 Sep 2013 23:00:00.000 9.34 m/sec
PM1 13 Sep 2013 16:36:08.000 16.96 m/sec
PM2 21 Sep 2013 11:53:19.000 17.492 m/sec
Planned Maneuvers
TCM1 01 Oct 2013 22:00:00.000 0.9 m/sec
LOI1 06 Oct 2013 10:57:00.210 329.86 m/sec
LAM1 07 Oct 2013 22:51:32.205 0 m/sec (error corrections for LOI-1)
LOI2 09 Oct 2013 10:37:55.651 295.99 m/sec
LOI3 12 Oct 2013 10:37:34.993 238.56 m/sec
