LRO in Commisioning Orbit about the Moon

At 8:34am EDT today LRO initiated LOI-5 which was a 230.8 second burn (36 m/s). This placed LRO in a 31x199km 90.2 degree inclination polar orbit. For those interested the orbital position of LRO after we acquired her on the ground when she came into view again is given in the telemetry screen snap. Please note ALL vectors are in the ECI coordinate system. Tomorrow we will transition LRO from solar-inertial pointing to lunar nadir pointing and begin spacecraft commissioning activities.

LOI-4 Successfully Completed

At 8:25am EDT today LRO executed LOI-4. This 10 minute propulsion burn placed LRO in a 200km circular polar orbit about the Moon. Now in this low circular orbit operations will begin to resemble our nominal mission with ground station passes coming and going on a regular frequency as we pass behind the Moon each orbit. During certain days every month the ground can see LRO for her entire orbit of the Moon. This is illustrated in the diagram above.

LRO Status 6/25/2009 8:30pm EST

A nominal day heading into our LOI-4 burn. We are in a 199x740km orbit with an inclination of 89.93 degrees. LOI-4 at 8:25am EDT tomorrow will put us in a 200km circular orbit.

Where's LRO? Available on LROC Homepage

Check it out, and the entire LROC homepage. http://lroc.sese.asu.edu/whereislro/

Links to homepages for all the LRO instruments can be found at the LRO GSFC website.

LOI 3 Burn Successfully Completed

At 06:32 am EDT, the LOI 3 burn was successfully conducted. The burn lasted for 12 minutes and placed LRO in a 2.58 hour orbit. Following the burn, a Delta-H momentum unload was performed.

A Delta-H maneuver is how LRO reduces its system angular momentum (H). Thrusters are fired in a manuver planned to reduce the reaction wheel speeds. At the moon LRO gains angular momentum from torques induced by gravity gradient effects, solar radiation pressure, and from the use of our thrusters for changes in velocity (orbit changes).

LOI 4 burn is scheduled for tomorrow at 8:25am EDT.

LRO Status 6/23/2009 6:35pm EDT

Since the LOI-2 burn the mission has unfolded per our planned timeline without any anomalies. At this point in the day the planning process for the upcoming LOI-3 burn has begun. LOI-3 will be at 6:32am EDT and lasts 13 minutes. This burn is the next in our series of 5 burns to place LRO in the commissioning orbit. The commissioning orbit is 30x216 km and is a quasi-frozen orbit which requires almost no fuel to maintain. In contrast our 50km circular nominal mission orbit requires about 90kg of fuel each year to maintain.

About a week and half after reaching the commissioning orbit we will begin activating the remaining instruments and start calibrating them. These have not been turned on yet for a number of reasons. First, the insertion at the Moon is a critical and time constrained phase of the mission and the prime focus is safely delivering LRO into the right orbit. Secondly, the instruments (except the radiation instruments which are already on) are not designed to yield very useful or interesting data from anywhere except LRO's planned orbits. The cameras in particular are designed to build their images as the lunar surfaces passes through their FOV at ~1.6 km/s as LRO orbits the Moon. They cannot be simply pointed at the moon or earth during our transit to the Moon and snap a photo. To better understand the line-array (NACs) and push-frame (WAC) camera designs an overview paper on LRO's instrument is available at http://lunar.gsfc.nasa.gov/library.html

LOI 2 Burn Successfully Completed

We have successfully completed the LOI 2 burn. All systems remain nominal. The burn lasted 12 minutes and has placed LRO in a 200x1680km above the Moon. 3 more burns remain to lower LRO into its 30x216 km commisioning orbit

LRO Status 5:00pm EDT 6/23/2009

LRO remains in orbit around the Moon. Everything continues to unfold according to our timeline with the exception of a transition to Sun-Safe Mode (safe-mode for LRO) at 11:50 am when AP22 (Action Point for Attitude Error) tripped. This was diagnosed as being caused by a bad Star tracker solution due to partial occultation by the Moon, the valid but incorrect quaternion caused the spacecraft to slew which in turn tripped AP22 due to attitude error. Normally the Kalman Filter would filter this out but at the time we were still checking out the Kalman Filter performance and were not yet controlling with it. By 12:28 pm EDT we were back in Observing Mode and by 2:00pm we had LEND and CRaTER back on. The GN&C team will issue a more complete report when the finish reviewing all the telemetry.

LOI-2 is scheduled for 6:56am on Wednesday 6/24/2009.