Mission: ICESat-2 Arctic Ocean #1 (racetrack)
Priority: Baseline
 
This new flight for 2019 flies a racetrack along a single ICESat-2 ground track, selected and timed so that our aircraft and the spacecraft fly the track as closely as possible in time, and also with the track drift-corrected according to winds measured from the aircraft. The particulars of the technique we will use to fly the track will depend on knowledge of ICESat-2’s pointing accuracy just prior to the time of this flight. Options include out-and-back along the same or parallel and offset lines, varying the altitude of one or both lines, or even a four-segment line. The general idea is to obtain a composite swath wide enough to capture any likely pointing offset of the spacecraft. See Appendix D of the flight plans document for more details on the design of these flights.
 
Having increased over the past week our confidence in our ability to forecast conditions northwest of Ellesmere Island, where most zero-latency ICESat-2 tracks are to be found at the present time during our flight window but lacking near-contemporaneous imagery, we opted for this critical baseline mission. Today was also an exciting day because the GPS week rolled over from 2047 to a new integer multiple of 1024 to 2048, which runs the risk of some Y2K-like symptoms because the GPS string only uses 10 bits to provide the least significant digits of the GPS week, with the rest left to software. This event that has not occurred since 1999 and caused some oddities in our displays. We will be pre-processing our data tonight to verify that no GPS data were impacted. During our transit, Ellesmere and Axel Heiberg islands were clouded over, as predicted, but cleared as we descended off the coast and in between two smaller islands. Few leads were observed as we surveyed ICESat-2 beams 1L and 2L three times each, with only minimal haze occasionally observed. Headwall VNIR and SWIR channels experienced brief freezes, and one Applanix IMU failed. Otherwise, all instruments performed well and ATM reports 100% laser altimetry data collection. Due to the higher survey AGL (3500 ft) to achieve overlapping ATM T6 (wide-scan) swath, snow radar was operated at 2-8 GHz. We conducted two x-chats with students from South Africa and Kentucky and finally we conducted a ramp pass at 1000 ft AGL.
 
ICESat-2 reference ground track (RGT) / latency (minutes, positive/negative = ICESat-2 orbits after/before our flight)
157 / 0
 
Attached images/files:

1. Map of today’s mission (John Sonntag / NASA)
2. KML of today’s mission (John Sonntag / NASA)
3. Pressure ridge origination of multiple snow drifts (Jeremy Harbeck / NASA)
4. One of the very few leads we observed today (Jeremy Harbeck / NASA)
5. Multi-year ice floe (Jeremy Harbeck / NASA)
6. CAMBOT image at time of direct ICESat-2 underflight (Jeremy Harbeck / NASA)