The Water Recovery X-ray Rocket (WRXR) is a sounding rocket payload that will launch from the Kwajalein Atoll in April 2018 and seeks to be the first astrophysics sounding rocket payload to be water recovered by NASA. WRXR's primary instrument is a grating spectrometer that consists of a mechanical collimator, X-ray reflection gratings, grazing-incidence mirrors, and a hybrid CMOS detector. The instrument will obtain a spectrum of the diffuse soft X-ray emission from the northern part of the Vela supernova remnant and is optimized for 3rd and 4th order OVII emission. Utilizing a field of view of 3.25° × 3.25° and resolving power of λ/δλ ≈40-50 in the lines of interest, the WRXR spectrometer aims to achieve the most highly-resolved spectrum of Vela's diffuse soft X-ray emission. This paper presents introductions to the payload and the science target.
Current theories regarding the matter composition of the universe suggest that half of the expected baryonic matter is missing. One region this could be residing in is intergalactic filaments which absorb strongly in the X-ray regime. Present space based technology is limited when it comes to imaging at these wavelengths and so new techniques are required. The Off-Plane Grating Rocket Experiment (OGRE) aims to produce the highest resolution spectrum of the binary star system Capella, a well-known X-ray source, in the soft X-ray range (0.2keV to 2keV). This will be achieved using a specialised payload combining three low technology readiness level components placed on-board a sub-orbital rocket. These three components consist of an array of large format off-plane X-ray diffraction gratings, a Wolter Type 1 mirror made using single crystal silicon, and the use of EM-CCDs to capture soft X-rays. Each of these components have been previously reviewed with OGRE being the first project to utilise them in a space observation mission. This paper focuses on the EM-CCDs (CCD207-40 by e2v) that will be used and their optimisation with a camera purposely designed for OGRE. Electron Multiplying gain curves were produced for the back-illuminated devices at -80C. Further tests which will need to be carried out are discussed and the impact of the OGRE mission on future projects mentioned.
Off-plane X-ray diffraction gratings with precision groove profiles at the submicron scale will be used in next generation X-ray spectrometers. Such gratings will be used on a current NASA suborbital rocket mission, the Off-plane Grating Rocket Experiment (OGRE), and have application for future grating missions. The fabrication of these gratings does not come without challenges. High performance off-plane gratings must be fabricated with precise radial grating patterns, optically at surfaces, and specific facet angles. Such gratings can be made using a series of common micro-fabrication techniques. The resulting process is highly customizable, making it useful for a variety of different mission architectures. In this paper, we detail the fabrication method used to produce high performance off-plane gratings and report the results of a preliminary qualification test of a grating fabricated in this manner. The grating was tested in the off-plane `Littrow' configuration, for which the grating is most efficient for a given diffraction order, and found to achieve 42% relative efficiency in the blaze order with respect to all diffracted light.
We present the first results from the Off-plane Grating Rocket for Extended Source Spectroscopy (OGRESS) sounding rocket payload based at the University of Iowa. OGRESS is designed to perform moderate resolution (R~10- 40) spectroscopy of diffuse celestial x-ray sources between 0.3 – 1.2 keV. A wire grid focuser constrains light from diffuse sources into a converging beam that feeds an array of off-plane diffraction gratings. The spectrum is focused onto Gaseous Electron Multiplier (GEM) detectors. OGRESS launched on the morning of May 2, 2015 and collected data for ~5 minutes before returning via parachute. OGRESS observed the Cygnus Loop supernova remnant with the goal of obtaining the most accurate physical diagnostics thus far recorded. During the flight, OGRESS had an unexpectedly high count rate which manifested as a highly uniform signal across the active area of the detector, swamping the expected spectrum from Cygnus. Efforts are still in progress to identify the source of this uniform signal and to discover if a usable spectrum can be extracted from the raw flight data.
The Off-plane Grating Rocket Experiment (OGRE) is a high resolution soft X-ray spectrometer sub-orbital rocket payload designed as a technology development platform for three low Technology Readiness Level (TRL) components. The incident photons will be focused using a light-weight, high resolution, single-crystal silicon optic. They are then dispersed conically according to wavelength by an array of off-plane gratings before being detected in a focal plane camera comprised of four Electron Multiplying Charge-Coupled Devices (EM-CCDs). While CCDs have been extensively used in space applications; EM-CCDs are seldom used in this environment and even more rarely for X-ray photon counting applications, making them a potential technology risk for larger scale X-ray observatories. This paper will discuss the reasons behind choosing EM-CCDs for the focal plane detector and the developments that have been recently made in the prototype camera electronics and thermal control system.
Photon counting detector systems on sounding rocket payloads often require interfacing asynchronous outputs with a synchronously clocked telemetry stream. Though this can be handled with an on-board computer, there are several low cost alternatives including custom hardware, microcontrollers, and Field-Programmable Gate Arrays (FPGAs). This paper outlines how a telemetry interface for detectors on a sounding rocket with asynchronous parallel digital output can be implemented using low cost FPGAs and minimal custom hardware. It also discusses how this system can be tested with a simulated telemetry chain in the small laboratory setting.
The Colorado High-resolution Echelle Stellar Spectrograph (CHESS) is a far ultraviolet (FUV) rocket-borne experiment designed to study the atomic-to-molecular transitions within translucent interstellar clouds. CHESS is an objective echelle spectrograph operating at f/12.4 and resolving power of 120,000 over a band pass of 100 – 160 nm. The echelle flight grating is the product of a research and development project with LightSmyth Inc. and was coated at Goddard Space Flight Center (GSFC) with Al+LiF. It has an empirically-determined groove density of 71.67 grooves/mm. At the Center for Astrophysics and Space Astronomy (CASA) at the University of Colorado (CU), we measured the efficiencies of the peak and adjacent dispersion orders throughout the 90 – 165 nm band pass to characterize the behavior of the grating for pre-flight calibrations and to assess the scattered-light behavior. The crossdispersing grating, developed and ruled by Horiba Jobin-Yvon, is a holographically-ruled, low line density (351 grooves/mm), powered optic with a toroidal surface curvature. The CHESS cross-disperser was also coated at GSFC; Cr+Al+LiF was deposited to enhance far-UV efficiency. Results from final efficiency and reflectivity measurements of both optics are presented. We utilize a cross-strip anode microchannel plate (MCP) detector built by Sensor Sciences to achieve high resolution (25 μm spatial resolution) and data collection rates (~ 106 photons/second) over a large format (40mm round, digitized to 8k x 8k) for the first time in an astronomical sounding rocket flight. The CHESS instrument was successfully launched from White Sands Missile Range on 24 May 2014. We present pre-flight sensitivity, effective area calculations, lab spectra and calibration results, and touch on first results and post-flight calibration plans.
The Off-plane Grating Rocket Experiment (OGRE) is a sub-orbital rocket payload designed to advance the development of several emerging technologies for use on space missions. The payload consists of a high resolution soft X-ray spectrometer based around an optic made from precision cut and ground, single crystal silicon mirrors, a module of off-plane gratings and a camera array based around Electron Multiplying CCD (EM-CCD) technology. This paper gives an overview of OGRE with emphasis on the detector array; specifically this paper will address the reasons that EM-CCDs are the detector of choice and the advantages and disadvantages that this technology offers.
We present the flight performance and preliminary science results from the first flight of the Sub-orbital Local
Interstellar Cloud Experiment (SLICE). SLICE is a rocket-borne far-ultraviolet instrument designed to study the diffuse
interstellar medium. The SLICE payload comprises a Cassegrain telescope with LiF-coated aluminum optics feeding a
Rowland Circle spectrograph operating at medium resolution (R ~ 5000) over the 102 – 107 nm bandpass. We present a
novel method for cleaning LiF-overcoated Al optics and the instrumental wavelength calibration, while the details of the
instrument design and assembly are presented in a companion proceeding (Kane et al. 2013). We focus primarily on
first results from the spring 2013 launch of SLICE in this work. SLICE was launched aboard a Terrier-Black Brant IX
sounding rocket from White Sands Missile Range to observe four hot stars sampling different interstellar sightlines. The
instrument acquired approximately 240 seconds of on-target time for the science spectra. We observe atomic and
molecular transitions (HI, OI, CII, OVI, H2) tracing a range of temperatures, ionization states, and molecular fractions in
diffuse interstellar clouds. Initial spectral synthesis results and future plans are discussed.
We present an overview of the Off-plane Grating Rocket for Extended Source Spectroscopy (OGRESS)
sounding rocket payload based at the University of Iowa. OGRESS is designed to perform moderate resolution (R~10-
40) spectroscopy of diffuse celestial X-ray sources between 0.3 – 1.2 keV. A wire grid focuser constrains light from
diffuse sources into a converging beam that feeds an array of diffraction gratings in the extreme off-plane mount. The
spectrum is focused onto Gaseous Electron Multiplier (GEM) detectors. Scheduled to launch in 2014, OGRESS will
obtain accurate physical diagnostics of the Cygnus Loop supernova remnant and will increase the technical readiness
level of GEMs. OGRESS is the fourth-generation of similar payloads from the partnership between the University of
Iowa and the University of Colorado, with higher throughput, and improved noise characteristics over its predecessors.
We present the fabrication and testing of the Sub-orbital Local Interstellar Cloud Experiment (SLICE), a rocket-borne
payload for ultraviolet astrophysics in the 1020 to 1070 Å bandpass. The SLICE optical system is composed of an
ultraviolet-optimized telescope feeding a Rowland Circle spectrograph. The telescope is an 8-inch Classical Cassegrain
operating at F/7, with Al optics overcoated with LiF for enhanced far-ultraviolet reflectivity. The holographically-ruled
grating focuses light at an open-faced microchannel plate detector employing an opaque RbBr photocathode. In this
proceeding, we describe the design trades and calibration issues confronted during the build-up of this payload. We
place particular emphasis on the technical details of the design, modifications, construction, and alignment procedures
for SLICE in order to provide a roadmap for the optimization of future ruggedized experiments for ultraviolet imaging
The Off-Plane Grating Rocket Experiment (OGRE) will greatly advance the current capabilities of soft X-ray grating spectroscopy and provide an important technological bridge towards future X-ray observatories. The OGRE sounding rocket will fly an innovative X-ray spectrograph operating at resolving powers of R ~ 2000 and effective areas < 100 cm2 in the 0.2–1.5 keV bandpass. This represents a factor of two improvement in spectral resolution over currently operating instruments. OGRE will observe the astrophysical X-ray calibration source Capella, which has a linedominated spectrum and will showcase the full capabilities of the OGRE spectrograph. We outline the mission design for OGRE and provide detailed overviews of relevant technologies to be integrated into the payload, including slumped glass mirrors, blazed reflection gratings customized for the off-plane mount, and electron-multiplying CCDs (EMCCDs). The OGRE mission will bring these components to a high technology readiness level, paving the way for the use of such a spectrograph on future X-ray observatories or Explorer-class missions.
The Far-ultraviolet Imaging Rocket Experiment (FIRE) is a sounding rocket payload that was designed to image the
Whirlpool Galaxy (M51) from 900-1000A and search for young, hot stars. Selected to match the GALEX mission
capabilities, FIRE has a resolution of 8 arcseconds with a 54 arcminute field-of-view. To achieve the desired wavelength
limits, FIRE utilized a single parabolic mirror coated with silicon carbide, an indium filter and a detector coated with
rubidium bromide. In combination, they gave a throughput of approximately 2% from 900-1000A with a throughput of
less than 10-5 at the major source of noise, 1216A Lyman-alpha. To ensure that the 2000A thick indium filter survived
launch, the filter and detector were encased in a vacuum canister where the pressure was maintained with a small ion
pump and opened after ascent to allow data collection. FIRE launched for the first time on January 28th, 2011 from
Poker Flat Research Range in northern Alaska with M51 as a primary target and G191B2B as a calibration target. This
flight culminated in the first ever astronomical image taken at the wavelengths of 900-1000A and was successful in all its
technology demonstration goals. This paper will describe the scientific motivation, design considerations and initial
We present the CODEX sounding rocket payload, a soft x-ray (0.1-1.0 keV) spectrometer designed to
observe diffuse high-surface brightness astronomical sources. The payload is composed of two modules, each with
a 3.25° x 3.25° field of view defined by a stack of wire grids that block light not coming to a 3.0 m focus and admit
only nearly-collimated light onto an array of 67 diffraction gratings in an off-plane mount. After a 2.0 m throw, the
spectrum is detected by offset large-format gaseous electron multiplier (GEM) detectors. CODEX will target the
Vela supernova remnant later this year to measure the temperature and abundances and to determine the
contributions of various soft x-ray emission mechanisms to the remnant's energy budget; resulting spectra will have
resolution (E/▵E) ranging from 50 to 100 across the band. CODEX is the third-generation of similar payloads from
the University of Colorado, with an increased bandpass, higher throughput, and a more robust mechanical structure
than its predecessors.
The International X-ray Observatory (IXO) is a collaborative effort between NASA, ESA, and JAXA. The IXO science
goals are heavily based on obtaining high quality X-ray spectra. In order to achieve this goal the science payload will
incorporate an array of gratings for high resolution, high throughput spectroscopy at the lowest X-ray energies, 0.3 - 1.0
keV. The spectrometer will address a number of important astrophysical goals such as studying the dynamics of clusters
of galaxies, determining how elements are created in the explosions of massive stars, and revealing most of the "normal"
matter in the universe which is currently thought to be hidden in hot filaments of gas stretching between galaxies. We
present here a mature design concept for an Off-Plane X-ray Grating Spectrometer (OP-XGS). This XGS concept has
seen recent significant advancements in optical and mechanical design. We present here an analysis of how the baseline
OP-XGS design fulfills the IXO science requirements for the XGS and the optical and mechanical details of this design.
We present results from the Extended X-ray Off-Plane Spectrometer (EXOS) sounding rocket payload. The
payload was launched on November 13, 2009 and successfully obtained a spectrum of the Cygnus Loop Supernova
Remnant. The instrument observed in the ~20 - 110 Angstrom bandpass with high resolution (~50) by utilizing an offplane
reflection grating array. This payload is also the 2nd flight for a relatively new type of detector, the Gaseous
Electron Multiplier (GEM) detector. We discuss the performance of these technologies in flight, as well as an overview
of our plans for the next flight of this design.
The International X-ray Observatory (IXO) is a merger of the former ESA XEUS and NASA Constellation-X missions,
with additional collaboration from JAXA, proposed for launch ~2020. IXO will address the leading astrophysical
questions in the 'hot universe' through its breakthrough capabilities in X-ray spectroscopy. The mission covers the 0.1
to 40 keV energy range, complementing the capabilities of the next generation observatories, such as ALMA, LSST,
JWST and 30 meter ground-based telescopes. An X-ray Grating Spectrometer is baselined to provide science in the
energy range 0.3-1.0 keV at a spectral resolution of E/ΔE > 3,000 with an effective area greater than 1,000 cm2. This
will require an array of soft X-ray enhanced CCDs operating at a modest frame rate to measure the diffracted light in
both position and energy. Here we describe the baseline camera for the Off-plane XGS instrument using mature CCD
We present an overview of the Extended X-ray Off-Plane Spectrometer (EXOS) Sounding Rocket Payload
based at the University of Colorado, Boulder. The program includes a total of four launches over the next four years on
various x-ray sources. The payload utilizes off-plane reflection gratings and Gaseous Electron Multiplier (GEM)
detectors in order to achieve both high throughput and resolution (R~100).
A dispersive spectrometer onboard the International X-ray Observatory (IXO) provides a method for high throughput and
high spectral resolution at X-ray energies below 1 keV. An off-plane reflection grating array maximizes these
capabilities. We present here a mature mechanical design that places the grating array on the spacecraft avionics bus
13.5 m away from the focal plane. In addition, we present the technology development plan for advancing the
Technology Readiness Level to 6 for the Off-Plane X-ray Grating Spectrometer.