Session D13: Ground-based and Space-based Instruments and Techniques

Current Status of QUIET

QUIET (the Q/U Imaging ExperimenT) is designed to measure the Cosmic Microwave Background polarization on large angular scales using sensitive HEMT-based polarimeters. The experiment targets the signature on the CMB of gravitational waves generated during inflation, known as B-mode polarization. Observations were made from October 2008 through May 2009 using a 19-element 40 GHz instrument coupled to a 1.4 meter telescope located at the Chajnantor Observatory in Chile. Observations with a 90-element 90 GHz instrument on the same telescope are ongoing. We describe the status of analysis of the 40 GHz data and the current 90 GHZ observations. At both frequencies, we target four patches totaling $\sim$1000 square degrees and chosen to have low foreground contamination. The current phase of QUIET will provide precise measurements of the E-mode polarization power spectrum and improve upper limits on B-modes for angular scales up to $\ell=1000$. Meanwhile, planning is underway for the second phase of QUIET, which will increase the number of detector by an order of magnitude to reach the level of sensitivity necessary to detect B-mode polarization.   

The Science and Design of the AGIS Observatory

The AGIS observatory is a next-generation array of imaging atmospheric Cherenkov telescopes (IACTs) for gamma-ray astronomy between 100~GeV and 100~TeV. The AGIS observatory is the next logical step in high energy gamma-ray astronomy, offering improved angular resolution and sensitivity compared to FERMI, and overlapping the high energy end of FERMI's sensitivity band. The baseline AGIS observatory will employ an array of 36 Schwarzschild-Couder IACTs in combination with a highly pixelated (0.05$^{\circ}$ diameter) camera. The instrument is designed to provide millicrab sensitivity over a wide (8$^{\circ}$ diameter) field of view, allowing both deep studies of faint point sources as well as efficient mapping of the Galactic plane and extended sources. I will describe science drivers behind the AGIS observatory and the design and status of the project.   

Toward Supernova Observations with the Micro-X High-Resolution Microcalorimeter X-ray Imaging Rocket

The Micro-X High-Resolution Microcalorimeter X-ray Imaging Rocket is a sounding rocket payload which will observe extended astrophysical X-ray sources with a focal plane array of transition-edge sensor microcalorimeters. An energy resolution of 2--4 eV over the 0.2--3.0 keV band, coupled with a $\sim~300$~cm$^2$ conical approximation Wolter-I mirror, will make high energy resolution imaging of extended sources possible. Puppis A, a bright supernova remnant, will be the first target. The line-dominated expected spectrum of the recently discovered ``silicon knot'' of Puppis A will provide a wealth of new information. Highly resolved Doppler shifts and broadening of emission lines will map out the dynamical structure of the ejecta. The ionization state of the plasma across the knot and between elements will be analyzed with the benefit of fewer model degeneracies. Additionally, estimates of elemental abundances in the remnant will be refined, and the spatial variations of enrichment across the knot will be mapped. The first flight is scheduled for January 2011. We will give an overview of the science goals and an update on our current progress.   

A tunable laser system for precision wavelength calibration of spectra

We present a novel laser-based wavelength calibration technique that improves the precision of astronomical spectroscopy, and solves a calibration problem inherent to multi-object spectroscopy. We have tested a prototype with the Hectochelle spectrograph at the MMT 6.5 m telescope. The Hectochelle is a high-dispersion, fiber-fed, multi-object spectrograph capable of recording up to 240 spectra simultaneously with a resolving power of 40000. The standard wavelength calibration method uses of spectra from ThAr hollow-cathode lamps shining directly onto the fibers. The difference in light path between calibration and science light as well as the uneven distribution of spectral lines are believed to introduce errors of up to several hundred m/s in the wavelength scale. Our tunable laser wavelength calibrator is bright enough for use with a dome screen, allowing the calibration light path to better match the science light path. Further, the laser is tuned in regular steps across a spectral order, creating a comb of evenly-spaced lines on the detector. Using the solar spectrum reflected from the atmosphere to record the same spectrum in every fiber, we show that laser wavelength calibration brings radial velocity uncertainties down below 100 m/s. We also present results from studies of globular clusters, and explain how the calibration technique can aid in stellar age determinations, studies of young stars, and searches for dark matter clumping in the galactic halo.   

Photoelectron Track Length Distributions in CH$_{3}$OCH$_{3}$ and Ne:CO$_{2}$:NO$_{2}$CH$_{3}$

We have measured the photoelectron track length distribution in 190 Torr CH$_{3}$OCH$_{3}$ and 400 Torr Ne:CO$_{2}$:NO$_{2}$CH$_{3}$, partial pressures 300:80:20 Torr, using a Time Projection Chamber Polarimeter (TPC) and Negative Ion TPC Polarimeter (NITPC) respectively. The measurements were made at the Brookhaven National Laboratory National Synchrotroon Light Source. Track length means range from 150 microns at 2.5 keV to 700 microns at 6 keV for CH$_{3}$OCH$_{3}$ and 150 microns at 3.0 keV to 700 microns at 7 keV. The track length mean vs energy was found to fit a powerlaw as reported for other gases. We found that for CH$_{3}$OCH$_{3, }$n=1.69 and for Ne:CO$_{2}$:NO$_{2}$CH$_{3,}$ n=1.72. This data has important implications for the design of the readout in future TPC's and NITPC's. TPC's and NITPC's for X-ray polarization were recently developed at NASA GSFC and a CH$_{3}$OCH$_{3}$ TPC will be the main instrument for the GEMS mission, a recently selected NASA SMEX.   

Database and Library Development of Organic Species using Gas Chromatography and Mass Spectral Measurements in Support of the Mars Science Laboratory

Our work involves the development of an organic contaminants database that will allow us to determine which compounds are found here on Earth and would be inadvertently detected in the Mars soil and gaseous samples as impurities. It will be used for the Sample Analysis at Mars (SAM) instrumentation analysis in the Mars Science Laboratory (MSL) rover scheduled for launch in 2011. In order to develop a comprehensive target database, we utilize the NIST Mass Spectral Library, Automated Mass Spectral Deconvolution and Identification System (AMDIS) and Ion Fingerprint Deconvolution (IFD) software to analyze the GC-MS data. We have analyzed data from commercial samples, such as paint and polymers, which have not been implemented into the rover and are now analyzing actual data from pyrolyzation on the rover. We have successfully developed an initial target compound database that will aid SAM in determining whether the components being analyzed come from Mars or are contaminants from either the rover itself or the Earth environment and are continuing to make improvements and adding data to the target contaminants database.   

Non-Linear Simulation for the Disturbance of Electronic Systems in Low Earth Orbits by High Energy Electrons

A Simulator is presented that models the disturbance of electrical circuits by high energy electrons trapped in earth's radiation belts; the model components are a module computing the electron fluence rate given the altitude, the time of the year, and the sunspot number, a module that models the interaction of the electrons with the materials of the electrical component, and a module that computes the charge and the magnitude of electrical field in the insulating materials as a function of time. The Adameic-Calderwood equation is used to model the relationship between the electrical conductivity of dielectric materials and the electric field intensity, making the charging/discharging equations highly non-linear. The non-linearity of the charging equations becomes especially pronounced in magnetic storms during intense solar flares. The results show that the electric field intensity can approach the dielectric breakdown strength in materials commonly used as dielectrics in space-based systems and that the fields can be sustained at high levels for as long as an hour.   

Speed Kills: Highly Relativistic Spaceflight Would be Fatal for People and Instruments

Stories, books and movies about space travel often describe journeys at near-light velocities. Such high speed is desirable, as the resulting relativistic time dilation reduces the duration of the trip, at least for the travelers, so that they can cover interstellar distances in a reasonable amount of time (by their own clocks) and live long enough to reach their destination. The relativistic rocket equation shows the enormous difficulty of achieving such velocities. As spaceship velocities approach the speed of light, interstellar hydrogen, although only present on average at a density of about 2 atoms per cm$^{3}$, impinges on the spacecraft and turns into intense radiation (Purcell, 1963) that would quickly kill passengers and destroy instrumentation. In addition, the energy loss of ionizing radiation passing through the ship's hull represents an increasing heat load which necessitates large expenditures of energy to cool the ship. Preventing this irradiation by the use of material or electromagnetic shields is a daunting and, as far as we know, unsolvable problem. The presence of interstellar hydrogen is yet another formidable obstacle to interstellar travel.