Post updated with launch pics! See below
We don’t usually do “current affairs” here, but this news release from NASA is worthy of a post, for several reasons.
First and foremost, it is an exciting mission, which NASA dubs: “The ‘Variable Sun’ Mission”. This is in itself a fresh departure, since NASA has been firmly in the “It can’t be anything else so it must be co2″ camp for years. Someone at mission control must have seen which way the solar wind is blowing, and has realized that what is needed is a “Five year mission to the centre of the solar system, to explore new worldviews, seek out new climate variables… To Boldly Go where no Mann has gone before”.
Secondly, it is of genuine interest to those of us who know that the Sun is a lot more variable than some (mentioning no names, Dr S.) have hitherto had people believe. The probe is designed to study the regions of the Sun’s broad range of radiation wavelengths and particle emissions which have the most variability, the extreme ultra-violet and the solar wind.
‘Solar constant’ is an oxymoron, says Judith Lean of the Naval Research Lab. “Satellite data show that the sun’s total irradiance rises and falls with the sunspot cycle by a significant amount.”
So, enough of the hyperbole, what about the hardware?
The SDO’s AIA ‘Atmospheric Imaging Assembly‘ will image the solar atmosphere in multiple wavelengths to link changes in the surface to interior changes. Data will include images of the Sun in 10 wavelengths every 10 seconds. It will have 1/2 greater image resolution than STEREO and 3/4 greater imaging resolution than SOHO at a resolution of about 1 arcsec. The image cadience also varies. SDO takes 1 image every second. At best STEREO takes 1 image every 3 minutes and SOHO takes 1 image every 12 minutes.
The EVE instrument has 70 times better spectral resolution in the Extreme UV than current measurements and has 30 times better time cadence / duty cycle to to understand variations on the timescales which influence Earth’s climate and near-Earth space.
Specific scientific objectives for the HMI instrument are to measure and study:
- Convection-zone dynamics and the solar dynamo;
- Origin and evolution of sunspots, active regions and complexes of activity;
- Sources and drivers of solar magnetic activity and disturbances;
- Links between the internal processes and dynamics of the corona and heliosphere;
- Precursors of solar disturbances for space-weather forecasts.
The HMI instrument will produce measurements in the form of filtergrams in a set of polarizations and spectral line positions at a regular cadence for the duration of the mission that meet these basic requirements:
- Full-disk Doppler velocity and line-of-sight magnetic flux images with 1.5 arc-sec resolution at least every 50 seconds.
- Full-disk vector magnetic images of the solar magnetic field with 1.5 arc-sec resolution at least every 10 minutes.
H/t to Oliver Manuel and Gray Stevens
Launch has been delayed again:
The new scheduled launch will be on Wednesday February 10, 2010 at 10:30
Bon Voyage SDO!
The Launch was a peach. Textbook precision from NASA. Congrats to all involved.