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  • | Where Earth's weather and space weather meet.
    Congratulations to the entire ICON team Onwards to Integration Posted in Milestones Tagged CDR ICON Review Comments Off on ICON passes Critical Design Review Pegasus Selected for ICON Launch Posted on January 7 2015 by Thomas Immel The Orbital Pegasus launch system was selected by NASA Launch Services to carry ICON into orbit ICON will be launched over the Pacific Ocean after taking off from Kwajalein Atoll on the Orbital L 1011 that is part of the Pegasus launch system Some pictures and discussion of the launch system can be found here There s a synopsis of the launch system on the SSL website as well It s a great way to get to space used successfully by many Explorers in the past Posted in Uncategorized Comments Off on Pegasus Selected for ICON Launch ICON Confirmed Proceed to Implementation Posted on November 13 2014 by Thomas Immel On October 29th 2014 the ICON mission was reviewed at NASA Headquarters where the project presented the status of the project focusing on the work that had been done to design and formulate the mission to the Science Mission Directorate and the Deputy Administrator for Programs at NASA HQ At this review ICON was successfully confirmed and was directed to proceed with formulation the mission The team has been working together through the successful Mission Preliminary Design Review in July and in the months that followed to reach this key milestones Preparation for this step has also been a focus for colleagues in the Explorers Office at Goddard Space Flight Center and in the Heliophysics Division at HQ Everyone involved is excited to proceed with the implementation of the mission Posted in Uncategorized Comments Off on ICON Confirmed Proceed to Implementation ICON Passes Preliminary Design Review Posted on July 24 2014 by Thomas Immel The ICON Mission has now passed its Preliminary Design Review where it is determined whether the design of the observatory and ground segment meet the mission requirements After a season of 35 peer and design reviews that started back in April the documentation and design for the Explorer were delivered and presented to the Standing Review Board at Orbital Congratulations to the whole team are due it has been an amazing effort The impressive list of reviews undertaken between SRR and PDR is given below Continue reading Posted in Milestones Comments Off on ICON Passes Preliminary Design Review ICON Passes System Requirements Review Posted on January 14 2014 by Thomas Immel The ICON mission has passed its System Requirements Review where the flowdown of top level requirements is traced through all aspects of mission implementation We ve gotten very good input from our Standing Review Board whose key concerns become top priorities for the team to close out Every NASA mission goes through this step on their way to the first design reviews and we re able to proceed with confidence that the team has a complete and verifiable set of requirements in hand ICON has had a great

    Original URL path: http://icon.ssl.berkeley.edu/ (2015-06-18)
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  • Science |
    this variability often occurs in concert with weather on our planet ICON will compare the impacts of these two drivers as they exert change on the space environment that surrounds us Figure 1 ICON s observational geometry allows simultaneous in situ and remote sensing of the ionosphere thermosphere system Though the solar inputs are now well quantified the drivers of ionospheric variability originating from lower atmospheric regions are not ICON is the first space mission to simultaneously retrieve all of the properties of the system that both influence and result from the dynamical and chemical coupling of the atmosphere and ionosphere ICON achieves this through an innovative measurement technique that combines remote optical imaging and in situ measurements of the plasma With this approach ICON gives us the ability to 1 separate the drivers and pinpoint the real cause of ionospheric variability 2 explain how energy and momentum from the lower atmosphere propagate into the space environment and 3 explain how these drivers set the stage for the extreme conditions of solar driven magnetic storms ICON s imaging capability combined with its in situ measurements on the same spacecraft Figure 1 gives a perspective of the coupled system that would

    Original URL path: http://icon.ssl.berkeley.edu/science/ (2015-06-18)
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  • Team |
    Berkeley Project Systems Engineer Dr Ellen Taylor UC Berkeley Payload Manager Mr Stewart Harris UC Berkeley Spacecraft Manager Ms Ann Cox Orbital Sciences Corporation Mission Operations Manager Dr Manfred Bester UC Berkeley Mission Assurance Manager Mr Jorg Fischer UC Berkeley The instrument leads are involved in almost all key design trades and play a critical role in informing design decisions whether potential changes can be made at the instrument or instrument component level payload level or need to consider a trade with the spacecraft and entire observatory They re also responsible for demonstrating that their instrument has the capability for meeting ICON s science requirements They ve done a great job in all aspects and are listed here Michelson Interferometer for Global High resolution Thermospheric Imaging MIGHTI Dr Christoph Englert Naval Research Lab Far Ultraviolet Imager FUV Dr Stephen Mende UC Berkeley Extreme Ultraviolet Imager EUV Dr Jerry Edelstein UC Berkeley Ion Velocity Meter IVM Dr Rod Heelis UT Dallas MIGHTI Optical Design Calibration Dr John Harlander St Cloud State EUV FUV Detector Systems Calibration Dr Oswald Siegmund UC Berkeley The ICON Science Team discusses each of the issues that affect science measurements to discuss which trades are acceptable or better yet beneficial During the study of the ICON concept several beneficial trades were made in the concept design that improved the precision of our scientific measurements Dr Immel also leads the ICON Science Team and discussed these trades with the team weekly during the Concept Study Science Team members are noted below Dr Gary Bust Applied Physics Laboratory Dr Geoffrey Crowley ASTRA Dr Scott England UC Berkeley Dr Harald Frey UC Berkeley Dr Jeffrey Forbes Colorado University Dr Joseph Huba Naval Research Laboratory Dr Farzad Kamalabadi University of Illinois Dr Astrid Maute High Altitude Observatory Dr Jonathan Makela University

    Original URL path: http://icon.ssl.berkeley.edu/team/ (2015-06-18)
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  • Instruments |
    and PhDs In the News Instruments ICON s payload of four sensitive instruments Michelson Interferometer for Global High Resolution Thermospheric Imaging MIGHTI Remotely measuring the neutral wind field and temperatures Heritage from SHIMMER flown on STPSat 1 Extreme Ultra Violet EUV Measuring the height and density of the daytime ionosphere Heritage from SPEAR flown on the Korean STSAT 1 Far Ultra Violet FUV Measuring the daytime atmospheric composition and the

    Original URL path: http://icon.ssl.berkeley.edu/instruments/ (2015-06-18)
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  • MIGHTI |
    2010a Figure 2 shows the monolithic inteferometer employed by SHIMMER WINDII used the same airglow emission lines to measure Doppler wind in the same altitude range as required for ICON The added capability based upon SHIMMER space flight heritage allows for a wind measurement virtually identical to WINDII and eliminates moving interferometer parts Figure 2 Photograph of the SHIMMER interferometer Harlander et al 2003 The MIGHTI design utilizes a cubic beam splitter Figure 3 Right Panel that allows for a smaller and lighter interferometer and and a more compact optical bench layout while maintaining excellent optical performance An engineering model of the interferometer is shown in Figure 3 Left Panel Figure 3 Left Engineering model of the MIGHTI interferometer Right Design for the MIGHTI interferometer The temperature of the lower thermosphere is derived from measurements of the band shape of the bright oxygen Atmospheric Band around 762nm Most recently this technique was applied using data from the OSIRIS satellite Sheese et al 2010 Similar measurements were also reported from the RAIDS instrument on the Space Station Christensen et al 2012 MIGHTI How it works The MIGHTI instrument consists of two sensor units with orthogonal fields of view pointed 45 and 135 from the S C velocity direction toward the port northern side of the spacecraft With this viewing geometry MIGHTI makes two perpendicular line of sight wind measurements of the same air volume less than 8 minutes apart Each measurement represents a set of limb observations for tangent altitudes between 90 and 300 km The vector combination from the two perpendicular lines of sight provides an altitude profile of wind vectors Temperature measurements are performed coincident with the wind measurements using multi color band shape measurements Conventional Michelson interferometers require mechanical stepping of a mirror to sample four or more path differences The Spatial Heterodyne Spectroscopy SHS approach for MIGHTI results in an improved more rugged design replacing the Michelson mirrors with fixed tilted diffraction gratings Fundamentally each facet or groove of the tilted gratings can be regarded as a separate interferometer mirror each representing a unique path difference which permits the sampling of many path differences without moving interferometer parts This eliminates the need for precision mirror stepping which simplifies both the instrument development and on orbit operation The SHS technique was demonstrated by both SHIMMER and the Redline DASH Demonstration Instrument REDDI two of the heritage instruments Englert et al 2010a b 2012 Harlander et al 2003 2010 The basic design of one of the two MIGHTI optical units is shown below Figure 4 Left Panel Because the measured interferogram is comprised of straight fringes rather than circular fringes produced by a Fabry Perot Interferometer for example the MIGHTI field of view can cover the entire limb altitude range required for the ICON science without a scanning mechanism Figure 4 Right Panel This eliminates a scanning mechanism and minimizes complexity in development and during on orbit operations The band shape measurement for the temperature retrieval is achieved using

    Original URL path: http://icon.ssl.berkeley.edu/instruments/mighti/ (2015-06-18)
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  • FUV |
    resolution to reject unwanted contamination by the bright optically thick 130 4 nm O line FUV is nominally pointed 20 o down towards nadir from the Y axis of ICON to image the northern limb and sub limb The ICON FUV instrument is illustrated on Figure 2 Figure 2 ICON FUV imager FUV The Details A small 40mm x 12mm motorized Steering Mirror is placed in front of the entrance slit to allow viewing approximately in the plane of the magnetic field The mirror has several fixed positions selectable by the instrument processor As in the IMAGE heritage instrument a sun sensor covering the full steering mirror range will command the safing of the high voltages to prevent instrument damage due to accidental direct sun exposure Light reflected by the steering mirror passes through a 6mm x 32mm entrance slit and is collimated by the first concave mirror Mirror 1 besides acting as the spectrograph collimator also focuses the scene viewed by the instrument near the grating producing an intermediate image The 4300 groves mm grating is slightly convex with a 1 7 m radius of curvature separates the O line illustrated in red from the N2 bands illustrated in blue Mirror 2 in combination with the back imager camera mirrors located behind each of the two exit slits reproduce the intermediate image on each detector There is an exit slit and the back imager camera consists of a de centered inverse Cassegrain configuration for each of the two bands Table 3 FUV Instrument Characteristics The two detectors for the ICON FUV instrument are microchannel plate MCP intensified CCD detectors with an active area of 25mm circular coupled to a 1K x 1K CCD similar to IMAGE WIC Mende et al 2000b The CCD is a Dalsa FTT1010M which is the same CCD used for ISUAL It will be binned 4 4 to achieve the desired 256 256 Adjacent 4 pixels will be co added to support the final 64 256 format easily meeting the detector spatial requirement Incident FUV photons strike the CsI photocathode of the sealed Photek image tube which is a modification of the Photek tube flown on the NASA TIMED mission launched December 07 2001 in the GUVI and in the DMSP SSUSSI instrument launched October 18 2003 The photoelectrons are multiplied by the 6 mm pore MCP with an overall gain set to a value controlled by the voltage applied across it The gain is chosen to optimize the dynamic range and sensitivity of the detector while conferring relative immunity to saturation when viewing bright dayglow The MCP output electrons are proximity focused onto an aluminized phosphor screen deposited on the output fiber optic window producing visible emissions imaged by the CCD bonded to the fiber optic Using TIMED GUVI limb data to evaluate the viewing conditions one may predict a scene in the FUV FOV with a mean brightness of 5 kR With this target brightness and detector the dual MCP electron gain can

    Original URL path: http://icon.ssl.berkeley.edu/instruments/fuv/ (2015-06-18)
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  • EUV |
    an order of magnitude less bright than the Earth s airglow The interpretation of the EUV dayglow builds on the recent success of the SSULI and RAIDS missions Figure 2 The ICON EUV instrument is based upon the UCB EURD astrophysical instruments Edelstein et al 2001 EUV How it works The ICON EUV spectral profiler is illustrated in Figure 3 The EUV instrument measures these emissions with a straightforward grating spectrograph that provides spectral information in one dimension horizontal on the 2D detector and altitude distribution of the emission brightness in the other dimension vertical The EUV uses a simple vertical push broom one dimensional imaging spectrograph of UCB design that consist of a single diffraction grating that directly views a wedge of sky through a fixed slit aperture The large difference in the vertical and horizontal curvature of the grating toroidal design permits the simultaneous vertical focusing of the scene located at great distances outside of the instrument and the horizontal focusing of the input slit located at the instrument entrance on the detector The view wedge is dispersed and imaged into a spectrum per field angle on a photon counting detector as shown in Figure 3 The simplicity of a single optic design results in a highly efficient instrument and eases alignment and calibration issues compared to multi optic designs Figure 3 The ICON EUV profiler EUV The Details The ICON EUV features an enclosed aluminum structural cavity withstanding 1 atm vacuum that acts as the optical bench and contains the diffraction grating and the open faced microchannel plate detector The instrument cavity can be hermetically sealed with a one time operable flap valve actuated in flight by a shape memory alloy mechanism A field of view entrance baffle extends beyond the optical entrance to eliminate solar panel glints and minimize sun pointing constraints To reject entrance of low energy ions into the optical cavity that could be accelerated into the MCP detector and cause excessive background noise the hermetic optical cavity uses a low voltage electric field applied to the slit and to fine metal grids placed over the entrance baffle the space venting aperture and the detector face inside the cavity The horizontal field 12 and the instrument scale set the ruled width of the grating to 40mm A 40mm tall entrance slit the imaging direction pupil and the imaging angle 16 sets the 90mm grating height The EURD type optical theory given a 3000 l mm ruling estimates the toroidal figure of the grating R 176 mm ρ 336 mm incident angle 13 7 and the optimum slit to grating distance and detector to grating incident angles 177 and 171 mm respectively Numerical ray tracing shows that the spectral resolution requirements allow a slit width of 890 µm which yields the per pixel geometric factor to 6 3 10 4 cm2 sr while maintaining a clean separation between 58 4 nm and 61 7 nm The glass diffraction grating uses straight holographic rulings blazed for

    Original URL path: http://icon.ssl.berkeley.edu/instruments/euv/ (2015-06-18)
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  • IVM |
    will appear on ICON IVM How it Works The Retarding Potential Analyzer is a planar sensor that presents a circular aperture to the incoming plasma stream that is intersected by a number of planar semi transparent conducting grids and a large solid collector Two schematic views of the RPA sensor are shown in figure 2 Figure 2 Schematic cross section and front view of the retarding potential analyzer The sensor is mounted to view approximately along the satellite velocity through a large aperture plane that provides a uniform planar electrical ground reference potential Grounded grids cover the entrance aperture to ensure that no internally applied potentials influence the ion beam trajectories prior to entering the sensor Inside the sensor the ion beam traverses a series of semi transparent grids before impacting the collector The retarding grids are biased at potentials between 0 and 25 volts and thus control the minimum energy that the ions must posses to reach the collector A suppressor grid prior to the collector is biased at 12 volts to reject ambient electrons and suppress photoelectrons ejected from the collector A current voltage characteristic is obtained by measuring the ion current while the retarding voltage moves over a series of predetermined discrete levels Retarding voltage sequences are chosen to optimize the sensor performance for the changing conditions expected in the ionosphere over a substantial part of a solar cycle Figure 3 shows a simulated data curve obtained assuming a total ion concentration or 10 5 cm 3 with 20 H and 80 O This current voltage characteristic has a well known functional form that can be fitted to retrieve the ion drift component along the sensor look direction termed the ion temperature and the major constituent ions The current at zero retarding voltage is used to derive the total ion number density Figure 3 RPA current voltage characteristic typical of topside ionosphere The Ion Drift Meter is a planar sensor that presents a square aperture to the incoming plasma stream that is intersected by a number of planar semi transparent conducting grids and a solid segmented collector The collector segments are arranged such that the cuts lie approximately along the satellite nadir and the orbit normal which define the local vertical and horizontal directions perpendicular to the satellite motion Two schematic views of the IDM sensor are shown in figure 4 Figure 4 Schematic cross section and front view of the ion drift meter The sensor is mounted to view approximately along the satellite velocity through a larger aperture plane that provides a uniform planar electrical ground reference potential Two planar grids are placed prior to the entrance aperture to prevent the passage of light ion species To ensure that no internally applied potentials influence the ambient external plasma the outermost grid which is coplanar with the aperture plane is always tied to reference ground as is the aperture plane This suppressor grid is biased at 12 volts to prevent access of ambient thermal electrons to the

    Original URL path: http://icon.ssl.berkeley.edu/instruments/ivm/ (2015-06-18)
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