Following its launch in August, 2005 and a year of interplanetary cruise and aero-braking, the successful Mars
Reconnaissance Orbiter (MRO) mission is currently orbiting Mars and down-linking imagery from the High Resolution
Imaging Science Experiment (HiRISE) camera. The primary objectives of the MRO mission are to characterize the
present climate of Mars, look for evidence of water-related activities, and characterize potential landing sites. After only
four months in the Primary Science Phase (PSP) of the mission, MRO has returned more data than any other previous
Mars mission. Approximately one-third of this data volume is from the HiRISE camera, built by Ball Aerospace &
Technologies Corporation (BATC), for the University of Arizona (UofA), Department of Planetary Sciences.
With a 0.5-meter primary mirror, the HiRISE instrument includes the largest optical telescope ever sent beyond Earth's
orbit, and is producing images with unprecedented resolution. It has detected objects of less than one meter size from
the nominal orbit of 250 x 320 km. The highest resolution images have a scale of 25 to 32 cm per pixel (1.0 microradian
IFOV). HiRISE is a "push-broom" camera with a swath width of 6 km in a broad red spectral band and 1.2 km in blue-green
and near infrared bands. There are 14 CCD detector chips (2048 x 128 TDI elements each) on the focal plane.
The HiRISE camera was designed to minimize use of spacecraft resources. Even with a half-meter primary mirror,
through the use of lightweight glass optics and graphite-composite structures the final mass of the instrument is only
64.2 kg. It maintains a nearly uniform telescope temperature of 20°C yet its orbital average power consumption is less
than 60 W.
An overview is given of the NASA MRO mission and the HiRISE instrument. Pre-launch activities are detailed and the
launch time discussed. An account is given of the cruise events, along with a description of aerobraking and the primary
science phase. A sample of science results are presented, including a wealth of imagery.
A laboratory development model (LDM) to demonstrate pointing, acquisition, and tracking (PAT) as applied to laser communications would provide valuable data as to efficiencies of different communication scenarios and network concepts. Such a system was designed, constructed, and tested to perform the PAT functions and to measure the effects on an actual laser communication link. Three PAT concepts were investigated for simulation. The first is an open-loop, one-way system in which a single beam director points in a serial manner to a number of remote stations. Acquisition is accomplished by assuring that the transmitted beam is sufficiently broad to cover the region of uncertainty of the receiver and that the field of view of the staring receiver is sufficiently broad to cover the region of uncertainty of the transmitter. The second concept is a two-way link, also employing a single beam director. The concept is similar to the traditional point-to-point lasercom link, requiring mutual acquisition and tracking. The third concept involves two beam directors, allowing slewing and acquisition of a new station while simultaneously communicating with a previous station. When the slew is complete, a beam to the switch redirects the communication beam to the second beam director. The process may be repeated in a 'leapfrog' manner until all stations have been communicated. These concepts were demonstrated by LDM hardware through generation of the necessary computer code. Other networks can easily be simulated by changes in the software.
The realization of a coherent frequency-modulated continuous-wave LIDAR aimed for the accurate measurement of short distances employing a distributed feedback tunable twin-guide laser diode is demonstrated. Theoretical calculations on the ultimate limits in accuracy of distance measurements as determined by the laser phase noise are carried out. A relative accuracy of 8x 10-5 (8 μm) for a single-shot measurement has been achieved at a distance of 10 cm, which is significantly better than expected from the laser linewidth. The results presented here prove the predictions calculated from theory.
This paper reports the performance and test results of a highpower
laser diode transmitter (HPLDT). The HPLDT provides a controlled
environment to operate semiconductor lasers with power levels
exceeding 0.5 W and is scalable to multi-watt output powers. It provides
thermal and optical power control and overdrive protection, and is capable
of modulating the laser at high data rates (up to i0 pulses/s). In
addition, the HPLDT can accommodate a variety of semiconductor lasers
and input modulating signal types over a wide bandwidth.
The space telescope imaging spectrograph (STIS) is currently being developed for in-orbit installation onto the Hubble Space Telescope in 1997, where it will cover the wavelength range from 115 to 1000 nm in a variety of spectroscopic and imaging modes. For coverage of the 305 - 1000 nm region (and backup of the 165 - 305 nm) region, STIS will employ a custom CCD detector which has been developed at Scientific Imaging Technologies (SITe; formerly Tektronix CCD Products Group). This backside-illuminated device incorporates a proprietary SITe backside treatment and anti-reflective coating to extend the useful quantum efficiency shortward of 200 nm. It also features low noise amplifiers, multi-pinned-phase implants, mini-channel implants, and four quadrant readout. The CCD is thermo-electrically cooled to an operating temperature of -80 degree(s)C within a sealed, evacuated housing with its exterior at room temperature to minimize the condensation of absorbing contaminants in orbit. It is coupled to a set of low noise, flexible, fault-tolerant electronics. Both housing and electronics are being developed by the STIS prime contractor, Ball Aerospace & Communications Group. We describe here the design features, performance, and fabrication status of the STIS CCD and its associated subsystem, along with results of radiation testing.
This paper describes a programmable timing generator designed and built to provide timing for focal plane arrays. The timing generator hardware consists of a plug-in board for a PC/XT/AT/386/486 personal computer. The board features 24 output channels, data rates from 175 Hz to 10 MHz, two levels of nested looping, and allows the bit rate to be changed while routine is being executed. Associated software includes a pattern editor, timing routine compiler, memory loader, and generator controller. The board has been successfully used to operate a 4 X 138 X 128 HgCdTe infrared array, a 2098 X 3 linear CCD array, and a 1024 X 1024 full-frame readout CCD. Although intended for use with focal plane arrays, the timing generator can be used in any application where multiple channels of complex and repeated timing are desired. For example, it was used to emulate a TMSC30 digital signal processor serial interface. The timing generator and associated software has proven to be easy to use, and take advantage of the PC/XT/AT/386/486 compatibility and popularity. The board is inexpensive due to the use of standard CMOS logic and one programmable gate array. The programmable part allows the design to be easily upgraded. Future plans include an upgrade to 3 levels of looping.
Development of a 2048-squared CCD for a second-generation Space Telescope instrument has produced some very encouraging devices. The first experimental lot of 10 devices have very few defects, dark currents of less than 40 electrons/pixel/hour at -80 C, readout noise levels of less than 4 electrons rms and excellent charge transfer efficiency at signal levels of less than 10 electrons.
A third-generation SAGE instrument is about to be designed as part of the NASA Earth Observational System. Previous instruments have used individual diodes as detectors. The new instrument will use a custom design CCD to dramatically enhance the study of the gas and aerosol components of the upper atmosphere. The CCD is a 3 by 400 imaging array that has a single serial register and an exposure control drain. It will be used at the focal plane of a spectrometer covering the spectral range from 288 nm to 1.02 micron.
Development of a 20482 CCD for a second-generation space telescope instrument has produced some very encouraging devices. The first experimental lot of 10 devices have very few defects, dark currents of less than 12 electrons/pixel/hour at -80 degree(s), readout noise levels of less than 4 electrons rms, and excellent charge transfer efficiency at signal levels of less than 10 electrons.
A third-generation SAGE instrument is about to be designed as part of the NASA Earth Observational System. Previous instruments have used individual diodes as detectors. The new instrument will use a custom design CCD to dramatically enhance the study of the gas and aerosol components of the upper atmosphere. The CCD is a 3 X 400 imaging array that has a single serial register and an exposure control drain. It will be used at the focal plane of a spectrometer covering the spectral range from 288 nm to 1.02 micrometers .
Charge Coupled Devices (CCDs) are the main imaging element in a variety of scientific and commercial applications. The interaction between the CCD and electronics is to achieve a quality image characterized by low-noise and low-smear, and meet frame-rate and linearity specifications. This course presents practical circuit applications and components, accompanied by appropriate theory, so the attendee has the tools to begin the electrical design of a working CCD imaging system. The course emphasizes standard design practice: understand the problem, propose a design, analyze the design using an appropriate math tool, then prototype, test and verify.