by Astrogator Mike | Oct 9, 2013 | General Comments
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:
And we are here in the orbit:
If you could see the orbit from Earth you’d see this:
by Astrogator Mike | Oct 9, 2013 | General Comments
Lunar Orbit Insertion Maneuver 2 (LOI-2) is upon us, scheduled for 09 Oct 2013 10:38 UTC. This maneuver will lower our periselene altitude from 15700 km down to 2220 km and change our orbit period from 24 hrs to 4 hrs.
The maneuver will last for 220.8 seconds, and will impart a delta-V (change in velocity) of 293 m/sec.
Right now LADEE sees this view:
And the orbit from above would look like this:
From Earth, if you could see the orbit, you’d see this:
Go LADEE!
by Astrogator Mike | Oct 8, 2013 | General Comments
LADEE is now in its last rev in the 24 hour capture orbit, and preparing for LOI-2, which will lower the spacecraft into a 4 hr orbit. LOI-2 is scheduled for 10:38 UTC (3:38 AM PDT) Wed. morning, Oct. 9. Here’s the view from LADEE to the Moon:
Here’s the orbit [Note: blue shows the 4 hr orbit we’re going to next. Dotted lines show the past trajectory, solid are into the future. So we’re not quite at aposelene yet.]
And finally the really cool view AstrogatorJohn came up with yesterday of the view of the orbit from the Earth:
So if you go outside tonight and see the Moon, imagine this orbit.
by Astrogator Mike | Oct 7, 2013 | General Comments
The LADEE Spacecraft successfully performed Lunar Orbit Insertion maneuver 1 (LOI-1) on Oct. 6, 2013 3:57 PDT. The LOI-1 maneuver captured LADEE into a 24 hr orbit. After 3 days (and 3 revs) in the capture orbit, the spacecraft will perform LOI-2 on Oct. 9 at 3:37 PDT. The second of 3 Lunar Orbit Insertion maneuvers, LOI-2 will reduce LADEE’s orbit down to a 4 hr orbit.
Finally, LOI-3 will be performed Oct. 12 at 8:00 PM PDT to circularize the spacecraft in a 235 km orbit. LADEE will spend a month in this “commissioning” orbit, while the spacecraft is checked out before full-time lunar science begins, and the Laser-Communications experiment will be tested.
At this time (7 Oct. 2013 7:53) LADEE is past its first aposelene, and is headed for its first periselene after capture.
by Astrogator Mike | Oct 6, 2013 | General Comments
The LADEE spacecraft is now in Lunar orbit. Tracking data will later confirm the precise parameters of the orbit, but based on telemetry of thruster performance and accelerations, the LOI-1 burn appears to be close to nominal.
The planned Lunar orbit has an orbit period of 23.1 hrs. The next planned maneuver (Lunar Aposelene Maneuver 1, or LAM1) is scheduled for the 2nd aposelene, which would occur roughly 1.5 days from now. For LOI-1 results close to nominal, this maneuver can be waived.
LOI-2 is nominally scheduled for 3 revs after LOI-1.
