2010-005A
The Solar Dynamics Observatory is the lead mission in NASA's Living With a Star (LWS) program. It will study the Sun at optical, ultraviolet and soft X-ray wavelengths from an inclined geosynchronous Earth orbit. The spacecraft was built in-house at NASA-Goddard; the mission is managed by GSFC and its control center is located there. What's new about SDO is that it will image the whole sun at very high cadence - typically returning new high resolution solar images every ten seconds, allowing the rapid evolution of solar activity to be studied. SDO will replace many of the capabilities of the elderly SOHO spacecraft which has been monitoring the Sun for 15 years.
SDO consists of a box-shaped service module with a GSFC-developed bipropellant propulsion system and a high gain antenna, topped by two tapered solar array wings and a science instrument module. The spacecraft has a dry mass of 1650 kg; at launch it also carries a propellant load of 1450 kg for its single main bipropellant R4D apogee thruster, which has a thrust of 445 Newtons. After it reaches geosynchronous orbit UNKNOWN kg of fuel will remain for stationkeeping operations. The propulsion system also contains 8 smaller 22N thrusters for attitude control.
The spacecraft is 4.5m high, 2.2m diameter, with a 6.5m span across the solar panels.
SDO will be launched from Space Launch Complex 41 at Cape Canaveral by a Lockheed-Martin Atlas V 401 model space launch vehicle, serial number AV-021, with a CCB first stage powered by one RD-180 engine, a single-engine RL10A-powered Centaur second stage, and a 4-m Large Payload Fairing. The first stage will separate 4 minutes 9s after launch and the first Centaur burn will last from T+4:19 to T+15:17. SDO and Centaur AV-021 will then be in an UNKNOWN (perigee x apogee x inclination) parking orbit. At T+1 hour 42 min 43s the Centaur will reignite for 3 min 15 s to reach a 2500 x 35355 km x 28.5 deg transfer orbit. SDO and AV-021 will separate at T+1h 48 min 46s.
The first apogee motor firing will occur at UNKNOWN after launch. After a total of 4 main engine firings, the spacecraft will be on station in view of the TDRS main ground station complex at White Sands.
SDO carries three main instruments - AIA, EVI and HMI, comprising a total of six imaging telescopes, three spectrographs and a photometer.
AIA, the Atmospheric Imaging Assembly (Lockheed/Palo Alto, A. Title, with telescopes built at SAO) will make temperature maps of the solar corona with 10 second cadence. The four 0.20m aperture normal-incidence EUV telescopes each have their 4096x4096 pixel CCD focal planes divided in two, with different narrow band filters on each half. The filters are centered on spectral lines which provide temperature diagnostics.
- AIA Telescope 1 sees 335A and 131A; - AIA Telescope 2 sees 211A and 193A; - AIA Telescope 3 sees 171A and a half-aperture measuring the UV and optical at 1600A (Carbon IV), 1700A (UV continuum) and a broad filter centered on 4500A (optical continuum). - AIA Telescope 4 sees 304A and 94A.
AIA sees the whole solar photosphere in its 41 arcmin field of view and has a spatial resolution of 0.6 arcseconds. It's this instrument that will provide the mission's most photogenic data.
EVE, the EUV Variability Experiment (Colorado/LASP, Woods) measures the EUV irradiance using its ESP, MEGS-A and MEGS-B spectrographs and the MEGS-SAM and MEGS-P instruments. EVE doesn't have spatial resolution, it just sums all the light from the Sun to make spectra.
- ESP (EUV Spectro-Photometer) is a non-focussing transmission grating spectrograph with 4 bands covering the 170-380A EUV range plus a zero order flux measurement in the 1-70A (0.2-12 keV) soft X-ray band, with 0.25 second cadence. - MEGS-A, the first part of the Multiple EUV Grating Spectrograph, covers the 50-370A EUV range with 1A resolution and 10s cadence on a 2048 x 1024 pixel CCD. It is a grazing incidence spectrograph. - MEGS-B is a normal incidence grating spectrograph for the 350-1050A FUV range; it also includes a photodiode, MEGS-P, for a measurement of the 1215A Lyman alpha line UV flux - MEGS-SAM is a pinhole camera for 1-70A X-ray event data. It shares the MEGS-A detector but has a separate aperture.
A version of EVE was test-flown on rocket NASA 36.233US on 2006 Oct 28, and further rockets will be flown during SDO's operation to help calibrate the instrument's accurate measurement of total solar output.
HMI, the Helioseismic and Vector Magnetic Imager (Stanford, Scherrer) is a single 0.14m-aperture telescope with a tunable filter and two 4096 x 4096 CCDs. It observes a 50A bandpass around 6768A in the optical, which contains a Ni I absorption line. Measurements of the Doppler shift and Zeeman splitting of this line generate maps of solar surface oscillations and the solar magnetic field. The field of view covers the whole solar disk with 1 arcsecond resolution.
Other solar space observatories currently in operation include Hinode, TRACE, RHESSI, SORCE, STEREO A/B and the SXI imager on GOES 14.
APL involved in LWS management; SDO built at GSFC.
HVMI will study the solar interior and AIA will study the solar atmosphere.
Launch 2010 by Atlas V 401 with 4-m Large PLF to GEO on azimuth 93.6.
3100 kg full inc 1450 kg prop. (PK) Size 4.5m x 2.2m, span 6.5 m.
Size is 2.2 x 2.2 x 4.5m box + 2 panels with 6.3m span.
GEO x 28 deg.
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| SDO |
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| Date | Time | Event | Orbit |
|---|
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| 2010 Feb 11 | 1523:00 | Launch by Atlas V 401 AV-021 | CC SLC41 |
| | | T+4:03 BECO |
| | | T+4:09 Stage 1 sep |
| | | T+4:19 MES1 |
| | | T+4:27 PLF sep |
| | 1530:00 | | -4161 x 259 x 28.8 |
| | 1540:00 | T+15:17 MECO-1 | 175 x 3706 x 28.7 |
| | 1705:43 | T+1:42:43 MES-2 3:15 |
| | 1708:57 | T+1:45:57 MECO-2 | 2480 x 35369 x 28.6 |
| | | 2:49 coast |
| | 1711:46 | T+1:48:46 Centaur/SDO sep |
| | | T+1:53:46 Begin CCAM |
| | | T+2:46:19 End depletion |
| | | | 2500 x 35355 km x 28.5 deg |
| 2010 Feb 12 | | | 666.20 2477 x 35301 x 28.5 |
| 2010 Feb 19 | | | 718.99 5099 x 35315 x 28.4 |
| 2010 Feb 22 | | | 750.40 6632 x 35318 x 28.4 |
| 2010 Feb 25 | | | 786.10 8338 x 35335 x 28.3 |
| 2010 Mar 1 | | | 931.45 15054 x 35376 x 28.3 |
| 2010 Mar 5 | | | 1049.48 20128 x 35533 x 28.2 |
| 2010 Mar 8 | | | 1150.57 24644 x 35343 x 28.2 |
| 2010 Mar 9 | 0250? | LAM | 1394.75 34574 x 35372 x 28.1 |
| 2010 Mar 10 | 1100? | LAM | 1406.09 34616 x 35777 x 28.0 GEO 142.1W+7.7E/d |
Payload:
