The COronal Solar Magnetism Observatory (COSMO) is a proposed facility with unique capabilities for magnetic field measurements in the solar atmosphere and corona to increase our understanding of solar physics and space weather. The observatory underwent a preliminary design review (PDR) in 2015. This paper summarizes the systems engineering plan for this facility as well as a preliminary overview of the concept of operations. In particular we detail the flow of science requirements to engineering requirements, and discuss an overview of requirements management, documentation management, interface control and overall verification and compliance processes. Operationally, we discuss the categories of operational modes, as well as an overview of a daily operational cycle.
The Coronal Solar Magnetism Observatory Large Coronagraph (COSMO-LC) is a 1.5 meter Lyot coronagraph dedicated to measuring magnetic fields and plasma properties in the solar corona. The COSMO-LC will be able to observe coronal emissions lines from 530-1100 nm using a filtergraph instrument. COSMO-LC will have a 1 degree field of view to observe the full solar corona out to 1 solar radius beyond the limb of the sun. This presented challenges due to the large Etendue of the system. The COSMO-LC spatial resolution is 2 arc-seconds per pixel (4k X 4k). The most critical part of the coronagraph is the objective lens that is exposed to direct sunlight that is five orders of magnitude brighter than the corona. Therefore, it is key to the operation of a coronagraph that the objective lens (O1) scatter as little light as possible, on order a few parts per million. The selection of the material and the polish applied to the O1 are critical in reducing scattered light. In this paper we discuss the design of the COSMO-LC and the detailed design of the O1 and other key parts of the COSMO-LC that keep stray light to a minimum. The result is an instrument with stray light below 5 millionths the brightness of the sun 50 arc-seconds from the sun. The COSMO-LC has just had a Preliminary Design Review (PDR) and the PDR design is presented.
The Coronal Solar Magnetism Observatory (COSMO) is a facility dedicated to measuring magnetic
fields in the corona and chromosphere of the Sun. It will be located on a mountaintop in the Hawaiian
Islands and will replace the current Mauna Loa Solar Observatory (MLSO). COSMO will employ a
suite of instruments to determine the magnetic field and plasma conditions in the solar atmosphere and
will enhance the value of data collected by other observatories on the ground (SOLIS, ATST, FASR)
and in space (SDO, Hinode, SOHO, GOES, STEREO, DSCOVR, Solar Probe+, Solar Orbiter). The
dynamics and energy flow in the corona are dominated by magnetic fields. To understand the
formation of Coronal Mass Ejections (CMEs), their relation to other forms of solar activity, and their
progression out into the solar wind requires measurements of coronal magnetic fields. The COSMO
suite includes the Large Coronagraph (LC), the Chromosphere and Prominence Magnetometer
(ChroMag) and the K-Coronagraph. The Large Coronagraph will employ a 1.5 meter fuse silica singlet
lens and birefringent filters to measure magnetic fields out to two solar radii. It will observe over a
wide range of wavelengths from 500 to 1100 nm providing the capability of observing a number of
coronal, chromospheric, and photospheric emission lines. Of particular importance to measuring
coronal magnetic fields are the forbidden emission lines of Fe XIII at 1074.7 nm and 1079.8 nm. These
lines are faint and require the very large aperture. NCAR and NSF have provided funding to bring the
COSMO Large Coronagraph to a preliminary design review (PDR) state by the end of 2013.
The COSMO K-Coronagraph is scheduled to replace the aging Mk4 K-Coronameter at the Mauna Loa Solar
Observatory of the National Center for Atmospheric Research in 2013. We present briefly the science objectives and
derived requirements, and the optical design. We single out two topics for more in-depth discussion: stray light, and
performance of the camera and polarimeter.
The High Resolution Imaging Science Experiment (HiRISE) camera will be launched in August 2005 onboard NASA's Mars Reconnaissance Orbiter (MRO) spacecraft. HiRISE supports the MRO Mission objectives through targeted imaging of nadir and off-nadir sites with high resolution and high signal to noise ratio [a]. The camera employs a 50 cm, f/24 all-reflective optical system and a time delay and integration (TDI) detector assembly to map the surface of Mars from an orbital altitude of ~ 300 km. The ground resolution of HiRISE will be < 1 meter with a broadband red channel that can image a 6 x 12 km region of Mars into a 20K x 40K pixel image. HiRISE will image the surface of Mars at three different color bands from 0.4 to 1.0 micrometers. In this paper the HiRISE mission and its camera optical design will be presented. Alignment and assembly techniques and test results will show that the HiRISE telescope's on-orbit wave front requirement of < 0.071 wave RMS (@633nm) will be met . The HiRISE cross track field is 1.14 degrees with IFOV 1.0 μ-radians.
The Reflection Grating Spectrometer of the Constellation-X mission has
two strong candidate configurations. The first configuration, the
in-plane grating (IPG), is a set of reflection gratings similar to
those flown on XMM-Newton and has grooves perpendicular to the
direction of incident light. In the second configuration, the
off-plane grating (OPG), the grooves are closer to being parallel to
the incident light, and diffract along a cone. It has advantages of
higher packing density, and higher reflectivity. Confinement of these
gratings to sub-apertures of the optic allow high spectral
resolution. We have developed a raytrace model and analysis technique
for the off-plane grating configuration. Initial estimates indicate
that first order resolving powers in excess of 1000 (defined with
half-energy width) are achievable for sufficiently long wavelengths
(λ ≥ 12Å), provided separate accommodation is made
for gratings in the subaperture region farther from the zeroth order
The proposed Micro-Arcsecond X-ray Imaging Mission (MAXIM) uses an array of spacecraft containing grazing incidence optics to create and acquire an image on a distant detector spacecraft. Among the technical challenges facing the mission, maintaining an acceptably small wavefront error in the optical system is addressed in this paper. Starting with a performance model for the observatory and both analytically- and raytrace-based optical sensitivities to misalignment and figure error, an error budget is constructed that includes the effects of the individual optical surfaces, the alignment of the optical elements within the 4-mirror periscope sub-assemblies, and the relative alignment of the many periscopes that make up the MAXIM optical imaging system. At this stage of conceptual development, the allocations to different sub-systems that affect wavefront error is based on the philosophy of "spreading the pain" associated with performance requirements of the contributing elements. The performance model and error budget become tools with which to explore different architectures and requirements allocations as the mission concept develops.
This paper discusses X-ray interferometer designs with milli-arcsecond resolution. The goal of this work was to derive interferometer designs that can be built and operated within the budget of a NASA mission. The current interferometer mission designs we propose use separate spacecraft for the optics and detector. Applying design techniques that desensitize the optical performance of the interferometer to spacecraft tip-tilt, and de-center errors was the goal of this work. An interferometer design will be presented with milli-arcsecond resolution. The requirements on relative motion between the spacecraft carrying the interferometer optics and the detector are discussed. Optical performance predictions will be shown.
The x-ray band of the spectrum is the natural place to perform super-high resolution imaging of astronomical objects. Because x-ray sources can have very intense surface brightness and interferometers can be made with very short baselines, x-ray interferometry has great potential. We will discuss MAXIM, the Micro-Arcsecond X-ray Imaging Mission and, in particular, MAXIM Pathfinder, a coordinated pair of x-ray astronomy missions designed to exploit the potential of x-ray interferometry. We will show how it is possible to achieve huge gains in resolution using today's technology. The Pathfinder mission will achieve resolution of 100 micro-arcseconds and will image the coronae of the nearby stars. MAXIM, with a design specification of 0.1 micro-arcseconds, has the goal of imaging the event horizons of massive black holes. We will explain the architecture of a possible Pathfinder mission and describe the activities NASA is supporting in the area of x-ray interferometry.
The MAXIM (Mico-Arcsecond X-Ray Imaging Mission) and MAXIM Pathfinder, a technology precursor mission, is considered by NASA as 'visionary missions' in space astronomy. Currently the MAXIM mission design would fly multiple spacecraft in formation, each carrying precision optics, to direct x-rays from an astronomical source to collector and imaging spacecrafts. The mission architecture is complex and provides technical challenges in formaiton flying and external metrology, and target acquisition. To further develop the concept, an integrated model (IM) of the MAXIM and MAXIM Pathfinder was developed. Individual subsystem models from disciplines in structural dynamics, optics, controls, signal processing, detector physics and disturbance modelign are seamlessly integrated into one cohesive model to efficiently support system level trades and analysis. The optical system design is a unique combination of optical concepts and therefore results from the IM were extensively compared with ASAP optical software.
MAXIM consists of thirty-two individual grazing incidence interferometer channels that act, in combination, like a high-resolution imaging telescope. In this paper, we will describe an optical design for Maxim and calculate principal optical tolerances. These tolerances offer advantages that make anticipated engineering challenges more soluble and affordable within the limitations of current technology. We also discuss key design tradeoffs that contribute to a preliminary tolerance budget.
The Astrobiology Explorer (ABE) is a MIDEX mission concept under study at NASA's Ames Research Center in collaboration with Ball Aerospace & Technologies, Corp. ABE will conduct IR spectroscopic observations to address important problems in astrobiology, astrochemistry, and astrophysics. The core observational program would make fundamental scientific progress in understanding the distribution, identity, and evolution of ices and organic matter in dense molecular clouds, young forming stellar systems, stellar outflows, the general diffuse ISM, HII regions, Solar System bodies, and external galaxies. The ABE instrument concept includes a 0.6 m aperture Cassegrain telescope and two moderate resolution (R equals 2000-3000) spectrographs covering the 2.5-16 micron spectral region. Large format (1024x1024 pixel or larger) IR detector arrays and bandpass filters will allow each spectrograph to cover an entire octave of spectral range or more per exposure without any moving parts. The telescope will be cooled below 50 K by a cryogenic dewar shielded by a sunshade. The detectors will be cooled to ~8K. The optimum orbital configuration for achieving the scientific objectives of the ABE mission is a low background, 1 AU Earth driftaway orbit requiring a Delta II launch vehicle. This configuration provides a low thermal background and allows adequate communications bandwidth and good access to the entire sky over the ~1-2 year mission lifetime.
Radiation exposure of CCD devices degrades the charge transfer inefficiency (CTI) by the creation of electron trap sights within the bulk silicon. The presence of electron traps tend to smear the signal of a point-like image. This affects CCDs used in star trackers where sub-pixel centroiding is required for accurate pointing knowledge. To explore the effects of radiation damage in CCD devices, we have developed a Monte-Carlo model for simulating charge transfer in buried channel CCDs. The model is based on the Shockley-Read-Hall generation-recombination theory. The CTI in CCD devices was measured before and after exposure to mono-energetic 61 MeV protons. Our data show that displacement damage in the bulk silicon increases the CTI of the CCD device. CTI was measure don irradiated CCD devices at various temperatures form -10 to -150 C, thus providing estimates of the electron trap energy levels created in the CCD silicon. The dominate post-radiation rap energy level was the silicon E-center found to be at an energy of 0.46 eV, which is in good agreement with other published values. To fit our data over the complete temperature range, we also required electron traps of 0.36 eV and 0.21 eV. Our model also includes the effects of charge cloud growth with signal volume and clocking rates of the CCD device. Determining the types and levels of radiation a CCD device will encounter during its operational life is very important for choosing CCD operating parameters.
We have developed an x-ray telescope that uses a new technique for focusing x-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype x-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degree graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 cm2 at 0.83 keV. Results from x-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the x-ray telescope's response to the SUn show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight.
Most methods of producing grazing incidence optics require expensive metrology equipment to achieve sub arcminute quality in the X-ray. At the University of Colorado we have been developing methods of manufacturing grazing incidence optics by grinding and polishing on aluminum and nickel surfaces that have been machined to within a few arcminutes on a conventional metal working lathe. The mirrors are tested during fabrication by the knife edge and Ronchi test which are simple optical tests requiring only a collimated source of visible light and a 50 line per inch screen, (Gallagher 1990). No metrology of the surface is done. At graze angles of a few degrees fabricating optics by this method is limited by diffraction of the highly obstructed pupil, but at visible wavelengths figuring to 10 or 20 arcseconds is still possible. This method cannot produce arcsecond quality X-ray mirrors by itself, but can be modified to do so when coupled with normal incidence testing of the optical surface by use of a reference test plate or profilometer. In this paper we only discuss the X-ray testing of a 218 mm diameter F/5.73 Wolter Type I telescope manufactured at the University of Colorado. The mirror flew on a NASA sounding rocket in March of 1991. Testing of the inplane and offplane imaging response at energies of .25 - 1.50 KeV and correlation with surface figure are discussed.
A Wolter type-I grazing incidence telescope is currently under construction
at the University of Colorado, Boulder. The telescope inirrors
were fabricated by machining on a lathe to approximately 1-2
arcminutes quality and ground and polished to improve their figures.
Current measurement of the telescope's image quality gives a FWHM
measurement of 44 arcseconds. We hope to achieve 5-10 arcsecond
quality when completed.