Mission: Thwaites-Getz 3 Beam IS-2
Priority: Medium
 
This new mission is designed to fly all three beam pairs of two crossing, low-latency, ICESat-2 ground tracks. These two low-latency tracks can be placed anywhere between the eastern shear margin of Thwaites Glacier, and roughly the eastern end of the Getz Ice Shelf, and above the grounding line. The mission has been modified to account for the orbit of ICESat-2 later today and early tomorrow, which places it west of Mounts Murphy and Takahe and east of Toney Mountain, rather than the eastern shear margin of Thwaites Glacier (as originally nominally designed). That places this mission in a region that OIB has not surveyed previously except near the grounding zone.
 
The forecast for this region as expected the day prior, and we viewed this as potentially our best opportunity to both survey a difficult-to-reach region and collect time- and space-coincident ICESat-2 data over land ice. We also corrected for the as-best-presently-understood latitude-dependent off-pointing of ICESat-2 from its RGTs, so as to get our best opportunity yet to obtain near-coincident OIB data beneath ICESat-2 over land ice. Finally, we also opted to survey at 3200 ft AGL so that ATM T6 (wide scan) could sample both beams in a pair along each track, and so that we could remain with one of the ideal operation altitude windows for the snow radar. We performed a ramp pass at 2000 ft AGL. We passed over Pine Island Bay, with Pine Island Glacier barely visible, then Thwaites Glacier and Crosson Ice Shelf before descending to begin the survey. Skies were clear throughout, and our underflights of these beam pairs went very smoothly, with no turbulence. We were treated to excellent views of Mts. Murphy and Takahe. We did not operate T7-IR during this mission, because our survey altitude (~3200 ft AGL) was significantly higher than that for which ATM had observed consistent IR returns previously (~2000 ft AGL). CAMBOT failed for about 30 min two thirds of the way through the flight, and Headwall SWIR also malfunctioned again briefly. Otherwise, all instruments reported excellent data collection today.
 
ICESat-2 RGT / Latency (hours, positive = OIB underflight ahead of ICESat-2)
676 / +2
683 / +13.5
 
Attached images/files:
1. Map of today’s mission (John Sonntag / NASA)
2. KML of today’s mission (John Sonntag / NASA)
3. The southernmost extent of marginal rifting along the western flank of Crosson Ice Shelf (Joe MacGregor / NASA)
4. The armada of icebergs that remains of Thwaites Glacier’s ice tongue, with its eastern ice shelf visible on the left of the image (Joe MacGregor / NASA)
5. Mt. Takahe (John Sonntag / NASA)
6. Surface texture change west of Mt. Takahe (John Sonntag / NASA)