David Wright

Optical Testing and Verification Methods for the James Webb Space Telescope Integrated Science Instrument Module Element

NASA’s James Webb Space Telescope (JWST) is a 6.5m diameter, segmented, deployable telescope for cryogenic IR space astronomy. The JWST Observatory includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM), that contains four science instruments (SI) and the Fine Guidance Sensor (FGS). The SIs are mounted to a composite metering structure. The SIs and FGS were integrated to the ISIM structure and optically tested at NASAs Goddard Space Flight Center using the Optical Telescope Element SIMulator (OSIM). OSIM is a full-field, cryogenic JWST telescope simulator. SI performance, including alignment and wavefront error, was evaluated using OSIM. We describe test and analysis methods for optical performance verification of the ISIM Element, with an emphasis on the processes used to plan and execute the test. The complexity of ISIM and OSIM drove us to develop a software tool for test planning that allows for configuration control of observations, implementation of associated scripts, and management of hardware and software limits and constraints, as well as tools for rapid data evaluation, and flexible re-planning in response to the unexpected. As examples of our test and analysis approach, we discuss how factors such as the ground test thermal environment are compensated in alignment. We describe how these innovative methods for test planning and execution and post-test analysis were instrumental in the verification program for the ISIM element, with enough information to allow the reader to consider these innovations and lessons learned in this successful effort in their future testing for other programs.

Management of the JWST MIRI pFM environmental and performance verification test campaign

The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the James Webb Space Telescope (JWST) observatory, scheduled for launch in 2018. It will provide unique capabilities to probe the distant or deeply dust-enshrouded regions of the Universe, investigating the history of star and planet formation from the earliest universe to the present day. To enable this the instrument optical module must be cooled below 7K, presenting specific challenges for the environmental testing and calibration activities. The assembly, integration and verification (AIV) activities for the proto-flight model (pFM) instrument ran from March 2010 to May 2012 at RAL where the instrument has been put through a full suite of environmental and performance tests with a non-conventional single cryo-test approach. In this paper we present an overview of the testing conducted on the MIRI pFM including ambient alignment testing, vibration testing, gravity release testing, cryogenic performance and calibration testing, functional testing at ambient and operational temperatures, thermal balance tests, and Electro-Magnetic Compatibility (EMC) testing. We discuss how tests were planned and managed to ensure that the whole AIV process remained on schedule and give an insight into the lessons learned from this process. We also show how the process of requirement verification for this complex system was managed and documented. We describe how the risks associated with a single long duration test at operating temperature were controlled so that the complete suite of environmental tests could be used to build up a full picture of instrument compliance.

System engineering and management in a large and diverse multinational consortium

This paper elaborates the system engineering methods that are being successfully employed within the European Consortium (EC) to deliver the Optical System of the Mid Infa-Red Instrument (MIRI) to the James Webb Space Telescope (JWST). The EC is a Consortium of 21 institutes located in 10 European countries and, at instrument level, it works in a 50/50 partnership with JPL who are providing the instrument cooler, software and detector systems. The paper will describe how the system engineering approach has been based upon proven principles used in the space industry but applied in a tailored way that best accommodates the differences in international practices and standards with a primary aim of ensuring a cost-effective solution which supports all science requirements for the mission. The paper will recall how the system engineering has been managed from the definition of the system requirements in early phase B, through the successful Critical Design Review at the end of phase C and up to the test and flight build activities that are presently in progress. Communication and coordination approaches will also be discussed.

John Knowles Paine: Selected Piano Works

interpretation of the dance pattern than an actual piece for dancing. The Romance begins in gently lyrical and evocative character; a more forceful middle section unsettled in key brings back a varied repetition. The turbulent Impromptu draws much of its energy from the Brahmsian opposition of two versus three notes per beat of the 3/4 meter; the middle section changes to a serene 6/8 time with a melody floating above the arpeggiated accompaniment. The cheerful Rondo giocoso chatters away in steady rhythm of sixteenth notes (with occasional triplets) in an ABABA pattern that moves from the tonic C to a bright E major for the first contrasting section, balanced by a move to the flat side for the second. Romance, Opus 12 The Romance, inscribed “To my friend Mr. Casimir Constable,” was published in 1869. Paine performed it on December 14,1868, as part of the same program that included his Opus 11.The program for the concert called the work “Fantasie Stück” (fantasy piece), a designation that seems more suited to this restless music than the softer term “romance.” The main section of the piece is in a dark march style, with harmonies shifting so constantly that the home key of E-flat is firmly established only in the final four bars. The sharply contrasted Trio, in A-flat, begins with a remarkable rhythmic feature: the melody appears twice, on 2 different beats of the measure, giving the impression of a very irregular rhythm. Of the major composers of the nineteenth century, only Brahms employs rhythmic phrase structure so flexibly as Paine does here. Three Piano Pieces, Opus 41 These three short, relatively light, pieces show a humorous side to Paine that is often overlooked, particularly when we rely for our impressions on the sober photographs of the muttonchopped elder musician. A Spring Idyl was dedicated to Miss Sarah D. Hoppin. From the technical point of view, it is an exercise in lightness of touch, particularly in the highly decorated right-hand part; expressively, it is a charming depiction of bird calls and rapid flickerings of wings in flight. The Birthday Impromptu was privately printed in 1882 as a gift to Paines friend, the Harvard professor W.G. Farlow. The score merely hints at the dedicatees name with a musical pun: After the words “A mon ami,” a hand points to a fragment of staff with a bass clef and the single note, the bottom F which Paine expects the knowing reader to identity as Farlow (“fa low”).The work itself is a tiny little jeu desprit, only 38 measures long, dying away with a gentle extended cadence. More than any other work, the Fuga giocosa shows the craftsman in a sportive mood, taking as his theme the baseball refrain, “Over the fence is out, boys,” Paine creates a formal—yet surprisingly chipper!—fugue that links at once his love for Bach and his identity as an American composer. Beginning as a strict fugue in three voices, Paine enriches the texture towards the middle, then returns to the lighter texture for several episodes. Valse Caprice Paine never published this composition. The manuscript, which bears no date, remained in the family without any public performances before being given to Harvard, suggesting the possibility that the work had a particularly private association for the composers relatives. It is one of the most challenging of all Paines piano compositions, with virtuosic devices (like the “thumb melody” under the brilliant figuration high on the keyboard) that Paine no doubt learned from the works of Liszt. Ten Sketches: In the Country, Opus 26 Also dating from 1876, In the Country was dedicated to Mme. Madeline Schiller. Amy Fay, a student of Franz Liszts, later to become well known for her delightful book Music Study in Germany, gave the first performance in Cambridge on May 8,1877 The set, or selected portions of it, was probably the most popular and frequently performed of all of Paines piano works. Each of its ten numbers offers a single musical image, evocative and colorful. Woodnotes, like the later Spring Idyl of Opus 41, suggests the call of birds in its lavish melodic ornaments. Wayside Flowers begins with a light-textured leisurely saunter, but the varied repetition of the opening is much enriched both harmonically and textually. Under the Lindens is Schumannesque in its presentation of a sustained melody picked out from the notes of the background arpeggiation. The Shepherds Lament tinges its melancholy with chromaticism. The Village Dance is a light-hearted movement; the beginning of the second strain deliciously varies the constant downbeat accent with accents on the last beat of the measure. Rainy Day grows out of staccato descending figures (scale segments and arpeggios) over which a sweet melody grows out of the opening notes. The Mill suggests the running water in its left-hand sixteenth-note figure that runs virtually throughout, evoking the world of a Schubert song cycle. Gipsies wanders harmonically with a constant rhythmic and accompaniment figure. Farewell is one of those expressive lyric inventions of which Paine was a master. The poignancy of departure is followed by the joy of return in Welcome Home, the most brilliant and most extended number in the set. Four Character Pieces, Opus 11 Paine performed this work on December 14,1868, at which time the program listed the movements with different headings than those that appear in the published score of 1872, yet they clearly represent the same four short pieces. At the time of publication, William F. Apthorp wrote in the Atlantic Monthly for October 1872 that they were “most free in form and full of genuine, unforced, at times almost startling originality.” The opening number, Frisch (“Fresh, lively”) features an extrovert melody over a busy sixteenth-note accompaniment, with momentary dark turns of the harmony. Feirlich (“Solemn”) projects its mood of subdued gravity by restricting the sonorities to the middle and lower range of the piano. Etwas bewegt (“Con moto”), is a 6/8 march, understated at first with staccato attacks, but growing in energy. The final movement, Willkommen (“Welcome”) had a personal meaning to the com3 poser, its mood, described by Apthorp as “bubbling-over animal spirits and genial joyousness.” In fact, Paine had written this piece to welcome his bride-to-be home from a journey; the original manuscript bears the heading “Welcome Home to my Darling Lizzie, from John, March 31,1868.” Funeral March in Memory of President Lincoln, Opus 9 Like many of his musical colleagues, Paine expressed in music his shock at the murder of President Lincoln, whom he greatly admired. (He left undeveloped a sketch for an orchestral tone poem on the subject of Lincoln). This march is cast in a long crescendo-decrescendo, as if a funeral procession were first heard in the distance, passed by in front of the listener, and then died away again in the distance. The march begins “con tenerezza” and pianissimo. The varied colors in the pianists attack (sforzandi, staccati) suggest muffled drums. Hints of somber fanfares mark the fuller middle section, then the procession marches away into silence. Romance, Opus 39 This Romance was dedicated to James Bradstreet Greenough. It was composed and published in 1883, the year of Greenoughs election to the rank of Professor of Latin at Harvard. Possibly the work was written in celebration of the event. Beginning in a gentle songful mood in D-flat, the piece builds gradually, by way of a diversion in F, to a climactic restatement of the opening material reaching fortissimo, then receding to a quiet close. Sonata in A minor, Opus 1 Paine was not one to shrink from a challenge. From the very beginning of his career he sought to write in the large forms, often explicitly in a genre that had been dominated by Beethoven, whose music had by mid-century become universally recognized as the touchstone of genius and inspiration. American Transcendentalists had found in Beethovens work an ethical and moral quality elevating it above that of any other composer. Small wonder, then, that a talented and idealistic American composer should pay explicit homage to the master from Bonn in such large-scale works as the Mass in D and the First Symphony. The earliest of Paines works in the Beethovenian mold is the piano sonata completed in Berlin in December 1859, when Paine was just twenty. He performed the work in public, but never published it. While Beethoven was very much part of his background, an equally potent figure was Bach, whose organ works Paine was practicing constantly. This may explain the somewhat “Bachian” quality of the opening theme in his sonata, which, although it is cast in the sonata form of the mid-nineteenth century, nonetheless generates the kind of rhythmic drive and motivic development that Paine would have learned from the music of the Leipzig Thomaskantor.The slow movement, in F, projects an exquisite melody over pedal-sustained chords; the contrasting middle section in F minor is more agitated, building to a high point that gradually descends to a varied restatement of the opening with recollections of the more agitated material at the end. In this sonata, as in both of his symphonies, Paines Scherzo demonstrates an affinity with the work of Beethoven—in its energy and drive and single-minded commitment to a particular musical gesture in the main section, as well as in its relaxation into a cantabile passage in the Trio. The key relations of the two sections (A minor for the Scherzo and F major for the Trio) echo the principal keys of the sonata as a whole: A (minor and major) for the first and last movements, F for the slow movement. The finales rondo theme again recalls the motivic energy of Bach, although the structure of the movement as a whole, the rather folksong-like character of the second theme, and the pianistic decorations of some passages are very much of the romantic era. Nocturne, Opus 45 Though this piece was not