On Saturday, we met with the CSBF crew for the formal flight readiness review of X-Calibur. During the review, the CSBF campaign manager goes through a checklist to ensure that the payload is ready to be launched. This includes availability of various pieces of documentation and certification, but also a discussion of the minimum criteria for a successful flight, as well as a documentation of the desired performance. We require a minimum flight duration of 8 days at an altitude of at least 120,000ft for a successful flight. This corresponds to a single revolution around the Antarctic continent. However, this does not mean that our flight will be terminated after that time. Instead, additional revolutions around Antarctica will be attempted in consultation with NSF, CSBF, and the science team. We will also likely fly higher than 120,000ft. Given the total payload mass of 5300lbs, the balloon is expected to carry X-Calibur to an altitude of 128,000 to 130,000ft. This is important to us because more X-rays will make it through the residual atmosphere above the balloon the higher we are, enhancing the sensitivity of the instrument.
On Friday morning when SuperTIGER was outside for its launch attempt, Scott Heatwole and Zach Peterson from Wallops Flight Facility performed the final flight balancing of the telescope truss. In order to achieve the best pointing performance, the telescope needs to be balanced very precisely. Unfortunately, SuperTIGER was not launched that morning owing to slightly too strong surface and low-level winds.
With the conclusion of the flight readiness review, X-Calibur is now formally flight ready. We are number 2 in line to be launched after SuperTIGER, which has been on the ice for an entire year, because the weather last year never permitted a launch. Now that we are done with our flight preparations, all we have to do is wait for the weather to permit a launch. The stratospheric circulation known as the polar vortex is already set up for the summer, all we need is a calm day on the ground. Unfortunately, the weather is expected to be bad until at least the end of the week. While we wait, we will continue to exercise the instrument and practice our flight operations procedures.