The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) was a diffraction limited 0.5m optical-to-near-UV telescope that was designed to study dark matter via cluster weak lensing. SuperBIT launched from Wanaka, New Zealand via NASA’s super-pressure balloon (SPB) technology on April 16, 2023 and remained in the stratosphere for 40 days. During the flight, SuperBIT obtained multi-band images for 30 science targets; data analysis to produce shear measurements for each target is ongoing. SuperBIT’s pointing system comprised three nested frames that stablized the entire telescope within 0.34 arcseconds rms, plus a back-end tip-tilt mirror that achieved focal plane image stability of 0.055 arcseconds rms during 300 second exposures. The power system reached full charge every day and never dropped below 30% at night. All components remained within their temperature limits, and actively controlled components remained within a standard deviation of ∼0.1K of their set point. In this paper we provide an overview of the flight trajectory behaviour and flight operations. The first two days of the flight were used for payload characterization and telescope alignment after which all night time was dedicated to science observations. Target scheduling was performed by an on-board “Autopilot” system which tracked available targets and prioritized completing targets over starting new targets. SuperBIT was the first balloon telescope to fly a Starlink dish to enable high-bandwidth communications with the payload. Prior to flight termination, two Data Retrieval System modules were deployed to provide a redundant data recovery method.
The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) is a near-diffraction-limited 0.5m telescope that launched via NASA’s super-pressure balloon technology on April 16, 2023. SuperBIT achieved precise pointing control through the use of three nested frames in conjunction with an optical Fine Guidance System (FGS), resulting in an average image stability of 0.055” over 300-second exposures. The SuperBIT FGS includes a tip-tilt fast-steering mirror that corrects for jitter on a pair of focal plane star cameras. In this paper, we leverage the empirical data from SuperBIT’s successful 39-day stratospheric mission to inform the FGS design for the next-generation balloon-borne telescope. The Gigapixel Balloon-borne Imaging Telescope (GigaBIT) is designed to be a 1.35m wide-field, high resolution imaging telescope, with specifications to extend the scale and capabilities beyond those of its predecessor SuperBIT. A description and analysis of the SuperBIT FGS will be presented along with methodologies for extrapolating this data to enhance GigaBIT’s FGS design and fine pointing control algorithm. We employ a systems engineering approach to outline and formalize the design constraints and specifications for GigaBIT’s FGS. GigaBIT, building on the SuperBIT legacy, is set to enhance high-resolution astronomical imaging, marking a significant advancement in the field of balloon-borne telescopes.
The Super Pressure Balloon-borne Imaging Telescope (SuperBIT) is a diffraction limited 0.5m optical-to-near-UV telescope launched from New Zealand on NASA’s Super Pressure Balloon (SPB) on April 16, 2023 and flew for 45 nights. There were several communication links used during SuperBIT’s flight to communicate with the telescope from the ground, including Starlink, the Tracking and Data Relay Satellite System (TDRSS), Pilot, and Iridium. While Starlink bandwidth was suitable for TCP-based communications and downlinking, the other links were only capable of supporting UDP-based communications. We designed a file transfer algorithm that downlinked files while detecting missing packets in our downlink and requested them automatically, saving limited bandwidth. We also developed a similar mechanism to upload files as 200-byte commands to SuperBIT. In addition to the downlink and uplink programs, we also created an “autopilot” program to automate observations based on the location, time, and a prioritized list of targets. In this paper, we discuss the communication and observation challenges that were faced and strategies we used to overcome these challenges while operating SuperBIT.
The Little Ultraviolet Camera (LUVCamera) is a low-cost, high-performance UV/optical camera system designed to support a range of space-based astronomical facilities. At the heart of LUVCamera is a GSENSE 4040-BSI scientific CMOS (sCMOS) sensor, similar to those found in commercial-off-the-shelf (COTS) cameras. Given the intended use of LUVCamera in space-based missions, it is crucial to understand not only the performance of the sensor, but also the degradation of that performance due to effects from radiation in space environments. In this work, we report our characterization results of a SBIG Aluma AC4040 which utilizes this sensor, as well as those of a SBIG Aluma AC2020 (based on the smaller GSENSE 2020-BSI) which has been exposed to radiation. Specifically, we detail the methods used to characterize the sensors along with measurements of the read noise (RN), dark current (DC), and absolute quantum efficiency (QE). Additionally, we report changes in those quantities after radiation exposure for the AC2020. We conclude that COTS sCMOS sensors such as these are sufficiently suited for applications in space-based missions.
KEYWORDS: Wavefronts, Wavefront sensors, Coronagraphy, Simulations, Electric fields, Cameras, Space telescopes, Signal to noise ratio, Exoplanets, Stars, Equipment, Imaging systems
Maintaining wavefront stability while directly imaging exoplanets over long exposure times is an ongoing problem in the field of high-contrast imaging. Robust and efficient high-order wavefront sensing and control systems are required for maintaining wavefront stability to counteract mechanical and thermal instabilities. Dark zone maintenance (DZM) has been proposed to address quasi-static optical aberrations and maintain high levels of contrast for coronagraphic space telescopes. To further experimentally test this approach for future missions, such as the Habitable Worlds Observatory, this paper quantifies the differences between the theoretical closed-loop contrast bounds and DZM performance on the High-contrast Imager for Complex Aperture Telescopes (HiCAT) testbed. The quantification of DZM is achieved by traversing important parameters of the system, specifically the total photon flux entering the aperture of the instrument, ranging from 1.85 × 106 to 1.85 × 108 photons per second, and the wavefront error drift rate, ranging from σdrift= 30−3000 pm/√ iteration, injected via the deformable mirror actuators. This is tested on the HiCAT testbed by injecting random walk drifts using two Boston Micromachines kilo deformable mirrors (DMs). The parameter scan is run on the HiCAT simulator and the HiCAT testbed where the corresponding results are compared to the model-based theoretical contrast bounds to analyze discrepancies. The results indicate an approximate one and a half order of magnitude difference between the theoretical bounds and testbed results.
Astronomy-grade cameras with robust performance and heritage in the space environment have long been costly, substantially limiting capacity for space-based astronomy and creating a resource barrier to access. Additionally, ultraviolet observations have historically been limited by the low-sensitivity of most sensors in this wavelength range. The LUVCam program is designed to address both issues, providing a high-performance, low-cost, UV/optical camera system sufficiently capable to support a wide-array of space-based astronomy missions. LUVCam features a large format, low-noise, large pixel, and high quantum efficiency, commercial-off-the-shelf backside illuminated CMOS sensor, packaged with custom built readout electronics and thermomechanical structure. LUVCam is ITAR-free, and cheap to fabricate, opening up new opportunities for access to space telescopes. LUVCam has reached TRL 6, and has passed qualification testing for operation in low-earth orbit, with competitive performance from 200-900 nm. LUVCam is manifested for multiple near-term orbital missions, including a technology demonstration CubeSat, and a UV transient astronomy SmallSat.
We present a low-cost ultraviolet to infrared absolute quantum efficiency detector characterization system developed using commercial off-the-shelf components. The key components of the experiment include a light source, a regulated power supply, a monochromator, an integrating sphere, and a calibrated photodiode. We provide a step-by-step procedure to construct the photon and quantum efficiency transfer curves of imaging sensors. We present results for the GSENSE 2020 BSI CMOS sensor and the Sony IMX 455 BSI CMOS sensor. As a reference for similar characterizations, we provide a list of parts and associated costs along with images of our setup.
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