EDIT: Merge Hack edits.

papers/hack/my_paper.rst

@@ -42,24 +42,30 @@ Introduction
 .. figure:: ariane5launch_sm.png
 
   An Ariane 5 launch similar to the launcher that will be used to 
-  place JWST into orbit about the L2 point. Photo: ESA.
+  place JWST into orbit about the L2 point, the orbital position 
+  that keeps the Sun behind the Earth all the time as viewed from JWST. 
+  Photo: ESA.
 
 The James Webb Space Telescope (JWST) will be NASA's next Great
 Observatory.  It will be an infrared-optimized telescope with a
 6.5m primary mirror made up of 18-separate segments 
-which will be launched in 2014
-by an Ariane 5 into an orbit at the L2 point about 1.5 million km
-from the Earth.  The Hubble Space Telescope (HST), by comparison,
+which will be launched no sooner than 2015
+by an Ariane 5 into an orbit at the second Langragian (L2) point. 
+This orbital position, about 1.5 million km
+from the Earth, keeps the Sun behind the Earth at all times making it easier 
+to shield the telescope and keep it cool.  
+The Hubble Space Telescope (HST), by comparison,
 is a telescope in a 570km high orbit with a solid 2.4m primary mirror
 optimized for UV and optical observations.   A lot of effort will go
 into building and testing JWST, as it did with HST, to get it to work 
-as desired and as reliably as possible once launched, however unlike HST, 
+as desired and as reliably as possible once launched. However, unlike HST, 
 there will not be any possibility of performing a repair mission.  
 The primary structure of JWST will be made of
 carbon-fiber composites in order to be lightweight enough for launch
 while still providing the necessary strength and rigidity to support
-such a large set of mirrors. The primary mirror will actually be
-composed of 18 separate hexagonal segments. These segments will be mounted 
+such a large set of mirrors and instrument packages. The primary mirror itself 
+will be composed of 18 separate hexagonal segments. 
+These segments will be mounted 
 onto a backplane with actuators that will allow the segments
 to be aligned to match one common optical surface that represents 
 a single mirror with a diameter of 6.5m.
@@ -87,7 +93,7 @@ NASA required a test that demonstrated the stability of this
 engineering article and which verified that the design and
 construction techniques will work to meet the requirements of the
 telescope: namely, that it will remain stable to within 68nm from
-30-50K (-405 to -370 :math:'\deg'F).  They also wished to track the
+30-50K (-405 to -370 :math:`^{\circ}\mathrm{F}`).  They also wished to track the
 structural changes from ambient (~295K) to cryogenic temperatures
 (~30K) in order to better understand the accuracy of their structural
 models.  The primary test equipment, a special interferometer,
@@ -103,8 +109,7 @@ small spatial scales. When illuminated by a laser, such surfaces
 typically show "speckles" that result from random points where the   
 reflections from the surface are relatively coherent (as compared to  
 the darker areas where the reflections mostly cancel out through  
-interference). While the phase of speckles varies randomly on a  
-spatial scale, and thus cannot be used for any spatial comparison from  
+interference). While the phase of speckles varies randomly from one spot on the article to the next, and thus cannot be used for any spatial comparison from  
 a single image, how the phase for a specific speckle changes, does  
 indicate how the surface is moving relative to the laser; in this way  
 speckle interferometers can be used to determine how surfaces are  
@@ -118,7 +123,7 @@ then recombines the reflected signal with a reference beam split from the same
 laser pulse, to create an interferometric map of the surface speckles.
 As the structure moves, the speckles change phase reflecting the
 change in interference between the incident and reference laser pulses.
-However, those phases cycle from :math:'-\pi' to :math:'\pi' and back
+However, those phases cycle from :math:`-\pi` to :math:`\pi` and back
 as the surface continues to move. This required the use of phase
 unwrapping across the surface, spatial phase unwrapping, using an
 algorithm developed by the manufacturers of the ESPI.
@@ -129,22 +134,26 @@ algorithm developed by the manufacturers of the ESPI.
   Schematic of ESPI showing how the ESPI measures the change in the object due to thermal or mechanical stress by tracking the speckles' phase change on the surface.
 
 As the surface tilted during the test, it produced fringes where
-the phases across the structure would transition from :math:'\pi'
-to :math:'-\pi'. This tilt needed to be removed in order to allow
+the phases across the structure would transition from :math:`\pi`
+to :math:`-\pi`. This tilt needed to be removed in order to allow
 us to measure the relative changes from one region of the structure
 to another.
 
 .. figure:: ESPI_tilt_schematic.jpg
 
-  Schematic showing how bulk tilt introduces multiple :math:'2\pi' variations across the structure and how it gets corrected in processing.
+  Schematic showing how bulk tilt introduces multiple :math:`2\pi` 
+  variations across the structure and how it gets corrected in processing,
+  allowing for relative variations to be measured across the surface as 
+  described in "Testing the BSTA".
+
 
-Since the measured phase is ambiguous by multiples of :math:'2\pi',
+Since the measured phase is ambiguous by multiples of :math:`2\pi`,
 special techniques are required to remove these ambiguities. One is
 to presume that continuous surfaces have continuous phase, and any
 discontinuities on continuous surfaces are due to phase wrapping. Thus
 such discontinuities can be "unwrapped" to produce spatially continuous
 phase variations. Another presumption is that even though the general
-position and tilt of the general structure may change greatly from one
+position and tilt of the entire structure may change greatly from one
 exposure to another, the relative phase shape of the structure will
 not change rapidly in time once bulk tilt and displacement are removed.
 
@@ -154,7 +163,7 @@ on spatially contiguous sections. Gross tilts are fit to the largest
 contiguous sections, and then the average tilt is removed (as well
 as the average displacement). However, there are areas of interest
 (the mirror pad supports) which are discontiguous and as a result
-possibly several factors of 2pi offset in reality as a result of the
+possibly several factors of :math:`2\pi` offset in reality as a result of the
 tilt, and thus improperly corrected when tilts are removed. Since
 these areas are assumed to change slowly in time, temporal phase
 unwrapping is applied to these areas.
@@ -182,7 +191,8 @@ were unknowable, not just unknown, for a number of reasons. No test
 had ever been conducted like this before, so there was no experience
 to draw upon to foresee what problems may arise during the test. Concerns
 ranged from whether the laser output could be maintained at a stable
-level given that the output was dependent on the ambient temperature
+level over such a long period of time given that the output was 
+dependent on the ambient temperature
 of the test facility.  This drove the requirement to monitor in 
 near-real-time the laser intensity as measured from the observations 
 themselves. These results were compared with occasional checks of 
@@ -195,16 +205,18 @@ to work until the test actually started. Test conditions such as
 residual vibrations in the test rig could seriously impact our ability
 to measure the surface changes we were after and potentially require
 changes to how the phase-unwrapping algorithms needed to be applied.
-It was only after the test started that these affects would be known, 
+It was only after the test started that these effects would be known, 
 requiring the ability to update the data acquisition and processing
 code on the fly to accommodate the quality of the test data.
 
-Finally, the code must be easily adaptable and handle massive amounts
-of data in as close to real-time as possible! Python offered the
-best possible choice for addressing these challenges in supporting
-this test.  It allowed us to rapidly develop code to adjust for the
+Finally, the code had to be easily adaptable and capable of handling 
+massive amounts of data in as close to real time as possible! 
+Python offered the best possible choice for addressing these 
+challenges in supporting
+this test.  It allowed us to develop code rapidly to adjust for the
 test conditions during the test with minimal impact.  The plotting and
-array-handling libraries proved robust and fast enough to keep up
+array-handling libraries, specifically matplotlib and numpy, 
+proved robust and fast enough to keep up
 with the near-real-time operations. The commercial software that
 came with ESPI hardware had also been written in Python and C, so
 Python allowed us to interface to that code to run our own custom
@@ -228,35 +240,39 @@ display of the latest processed image, all using matplotlib.
 
   This snapshot of the ESPI Monitoring GUI in operation illustrates the near-real-time monitoring plots and image display used to track the health of the laser and quality of the data and subsequent processing.
 
-This data processing pipeline was setup using 4 PCs and a 15Tb storage
+This data processing pipeline was set up using 4 PCs and a 15Tb storage
 server. A separate PC was dedicated to each of the processing steps;
 namely, data acquisition, initial phase unwrapping, measuring of
 regions, and monitoring of the processing.  This distributed system
 was required in order to support the data acquisition rate for the
 test: 5 1004x996 pixel images per second for 24 hours a day for 6
 uninterrupted weeks.   A total of approximately 11Tb of raw data
-was eventually acquired during the test. This raw data was later
+was eventually acquired during the test. These raw observations were later
 reprocessed several times using the original set of 4 PCs from the
 test as well as additional PCs all running simultaneously to refine
-the results in much less than real-time using all the lessons learned
-while the test was in progress.
+the results in much less than real time using all the lessons learned
+while the test was in progress. This reprocessing effort represented the 
+simplest possible case of parallel processing, where separate sets of data
+could be processed independently on separate systems. No other use of 
+parallel processing techniques was implemented for the test or 
+subsequent reprocessing.
 
 
 Results
 -------
 
-BSTA data analysis measured slope(expansion) sensitivity with an RMS of 25.2nm/K,
-well within the 36.8nm rms/K requirement for meeting NASA's goals. These
+BSTA data analysis measured the slope of the data, expansion due to temperature, with an RMS of 25.2nm/K,
+well within the 36.8nm/K requirement for meeting NASA's goals. These
 measurements were based on calibrations which had RMS values less
-than 5 nm around measured slope.
+than 5 nm around the measured slope.
 
 .. figure:: distortion_40to60K_ACAP4_mosaic.png
 
   Mosaic of sample processed measurements of the BSTA as the temperature changed from 40K to 60K, matching the operational temperature range of JWST. This mosaic illustrates how the structure was measured to change as the temperature changed.
 
-Python allowed for rapid development near-real-time processing
-pipeline spread across multiple systems which we were able to quickly
-revise as needed during the test.  The fact that the commercial software
+Python allowed for rapid development of a near-real-time processing
+pipeline spread across multiple systems which we were able to
+revise quickly as needed during the test.  The fact that the commercial software
 was written using Python also allowed us to interface with it
 to use their C-based algorithms for data acquisition
 and phase-unwrapping.  Equally importantly, we were able to implement
@@ -280,12 +296,12 @@ positions and orientations of each of the mirror segments will use an
 upgraded version of the ESPI to monitor the mirror segments after they 
 have been mounted on the backplane of the telescope.  This test will 
 validate that the actuators controlling the position of each mirror segment
-can be controlled sufficiently well enough to align all the segments to 
+can be controlled sufficiently to align all the segments to 
 create a single optical surface.  
 
-This test will require taking up to a
-1000 images a second for a short period of time after the mirrors have been
-adjusted to verify their positions, a test that can easily generate 10Tb of 
+This test will require adjusting the mirror positions, then taking up to a
+thousand images a second for a short period of time to verify the newly 
+updated positions. Such a test can easily generate 10Tb of 
 imaging data in only 7 minutes.  The Python software we developed for 
 previous ESPI tests will be used as the basis for the data acquisition and
 data processing systems for this new test, including synthesizing data from