SOLAR SVW bridging: outcome SOLAR Bridging of SVWs in Nov/Dec 2012 Outcome POIWG 33 – Huntsville, AL January 2013

SOLAR SVW bridging: outcome Outline Introduction to SOLAR payload SOLAR scientific goals The Bridging: why, when and what? Preliminary Results –Operations –Science Conclusion 2POIWG 33 - Huntsville, AL

SOLAR SVW bridging: outcome Introduction to SOLAR payload Integrated platform accommodating three instruments, tracking the Sun Location: Zenith external platform of Columbus Observation time: +/- 20 min per orbit during ‘Sun Visibility Window’ (SVW) Launched 7 Feb 2008, installed during 1E Lifetime: extension to POIWG 33 - Huntsville, AL

SOLAR SVW bridging: outcome ISS top view Solar 425 Jul 2012POIWG 32 - Huntsville, AL

SOLAR SVW bridging: outcome Going towards the 5 years! (picture courtesy NASA)

SOLAR SVW bridging: outcome SOLAR scientific goals Solar irradiance measurements from outside the atmosphere Sun pointing capability to have long enough continuous observation times to record complete spectrum Measurements if possible during a complete solar cycle (mission extension) Measurements during a full solar rotation (~27 days) for irradiance variations vs. sun spots 6POIWG 33 - Huntsville, AL

SOLAR SVW bridging: outcome 7POIWG 33 - Huntsville, AL

SOLAR SVW bridging: outcome The Bridging Why? By changing ISS attitude 2 SVW can be bridged  full solar rotation can be observed. What? From YPR (-4.0,-1.9,+ 0.6) to (-11.5,-1.9,-0.1)  The SOLAR Attitude! When? 30 Nov – 12 Dec to bridge Nov and Dec SVWs POIWG 33 - Huntsville, AL8

SOLAR SVW bridging: outcome Jan 2012POIWG 33 - Huntsville, AL9

SOLAR SVW bridging: outcome Jan 2012POIWG 33 - Huntsville, AL10 Tracking pass duration during SVW59 and 60

SOLAR SVW bridging: outcome

Preliminary Results: Operations All science measurements performed with success! Despite few SOLAR anomalies and thruster firings events. SOLAR main operational constraints: –Influence of thruster firings no science SolACES must be heated ~ 1day before and after –SAA –Ventings –TDRSS coverage (manual commanding) POIWG 33 - Huntsville, AL12

SOLAR SVW bridging: outcome The variability of the Sun irradiance presents a wide range of periodicity: 11-years solar cycle, periodicity of a few minutes for the Extreme UV induced by the presence of active regions, …. Due to the solar rotation, also a geometrically induced variability of 27 days is of course observed; The measurement of solar spectral irradiance (SSI) from space is important for solar physics, climatology and Earth atmospheric modelling. Continuous time series are of utmost importance under a worldwide effort to combine measurements from different instruments in EUV and UV-VIS spectrophotometry; However: degradation of instrumentation is still the primary problem limiting the accuracy of the derived solar spectral irradiance! How to distinguish evolution in data due to degradation from evolution due to irradiance variability? After 2002, a new generation of instruments are using internal calibration procedures (SOLACES & SOLSPEC, SORCE instruments, Sciamachy, …). It is the goal to analyze the calibration methods and the specific instrumental efficiency changes hampering the accuracy of data available in order to finally “melt” the data into one set of time-evolution SSI data. Allowing for continuous month-long measurements bring us closer to this goal. Science background

SOLAR SVW bridging: outcome Since the SolACES + SOLSPEC measurements are interrupted periodically due to the ISS orbital mechanics and the limitation of the solar pointing range of the SOLAR CPD, there was no chance to cover a full solar rotation period before. By bridging two succeeding measurement campaigns of days, the entire 27-day Sun rotation period can be followed. With a total of 35 consecutive measurements days this purpose is well met during Nov-Dec-2012 windows bridging; Hence this allows to: -Verify by cross-comparison the ability of existing instruments for measuring the right amplitude of the Sun irradiance variability. -Help for modelling of sunspots, faculae and their effect on UV irradiance for a better prediction of solar activity. -For Sol-ACES: inter-comparison of extreme UV irradiance measurements as provided by SDO in order to reduce uncertainties of absolute scales. -For SOLSPEC: inter-comparison between the variability of UV irradiance and solar proxy (MgII index).

SOLAR SVW bridging: outcome Preliminary Results: Science SOLSPEC: -For simultaneous study of the MgII index and the solar UV variability below 250 nm with high Signal-to-Noise ratio, special commands were created and daily used; -Also, nominal solar measurements (3 channels, full spectral range) and internal lamps spectra (ribbon tungsten and hollow cathode) have been performed on a daily base; -In total 174 SOLSPEC scripts were planned for the extended SVW, 100% of them executed! SOLACES: -Spectrometers count rates showed improvement by factor of 4 for start of bridged windows; -Special occasion to collaborate with groups in Los Angeles and Boulder. Groups also very aware so able to cross-correlate data; -In total 30 SOLACES scripts were planned for the extended SVW, 99% of them executed!

SOLAR SVW bridging: outcome Preliminary results report has been received by ESA from SOLACES / SOLSPEC science teams on 21-Jan, showing very good preliminary results already; For SOLACES, the results are enabling the effort to fill up the data gaps and to elaborate the ‘melted’ EUV data set in cooperation with the other teams involved. In this context we have come closer to the common goal for SOLAR of “quasi-continuous measurement of the solar irradiance variability with highest possible accuracy”; The first results of the bridging period confirm the breakthrough to provide first time a complete set of solar spectral irradiance EUV data starting in 2002 till today; For SOLSPEC, offering the opportunity of simultaneous measurements of spectral irradiance and the MgII proxy, the main efforts were focused on the determination of the scaling factors and comparisons of UV changes with SORCE and modelling. This is a crucial work that will improve SOLSPEC to better detect the solar UV variability and maintain the absolute scales without the deuterium lamps. The special commands developed for the bridging allowed the development of these works that should be extended to other proxies measured (CaII index) and comparisons with imagery of active regions during the bridging.

SOLAR SVW bridging: outcome Examples of first preliminary results: -Excellent agreement between SOLACES data and SDO / EVE data in the wavelength range 16-30nm (left); -From SOLSPEC data: For the MgII index, the results provided the signature of the solar activity using this proxy correlated to the chromosphere’s emissions (right). Future bridging periods are investigated to select reliable data sets to improve the accuracy of the data on one side and to fill up the data pool in a way that a full solar cycle will be covered.

SOLAR SVW bridging: outcome Conclusion Extensive preparation involving IPs Great cooperation from all partners Successful SOLAR operations during the whole bridging Science teams are reporting excellent scientific results thanks to bridging period! Science teams are happy so are we! Looking forward for next bridging. POIWG 33 - Huntsville, AL18

SOLAR SVW bridging: outcome Forward look

SOLAR SVW bridging: outcome Back-up slides POIWG 33 - Huntsville, AL20

SOLAR SVW bridging: outcome SOLAR instruments: SOVIM Total sun irradiance measurement Precision measurement of irradiance variability Instrument stopped functioning (power supply board failure) POIWG 33 - Huntsville, AL21

SOLAR SVW bridging: outcome SOLAR instruments: SOLSPEC Measure the solar spectrum irradiance from 180 nm to 3000 nm Precision measurement of irradiance variability Study of solar variability at short and long term Absolute measurements (2% in UV and 1% above) POIWG 33 - Huntsville, AL22

SOLAR SVW bridging: outcome SOLAR instruments: SOLACES Solar spectral irradiance of the full disk from 17 to 220 nm at 0.5 to 2 nm spectral resolution (4 EUV spectrometers) Auto-calibration capability: high absolute resolution Absolute calibration with ionization chambers as secondary instruments POIWG 33 - Huntsville, AL23

SOLAR SVW bridging: outcome Influence ISS attitude on SVW 24POIWG 33 - Huntsville, AL

SOLAR SVW bridging: outcome Influence ISS attitude on SVW 25POIWG 33 - Huntsville, AL YPR = (0,0,0) YPR = (0,0,- B) YPR = (+A,0,-B) YPR = (+A,0,0)

SOLAR SVW bridging: outcome Proposed options for SVW bridging Option 1: tweaking +XVV attitude away from TEA (torque equilibrium attitude) with CMGs within capabilities of MMS Option 2: going to +/-YVV attitude POIWG 33 - Huntsville, AL26

SOLAR SVW bridging: outcome Proposed options for SVW bridging (2/2) POIWG 33 - Huntsville, AL27 +XVV Bias-YVV