Fresh on the heels of their successful Chandrayann-3 mission, the Indian Space
Research Organization will be launching a probe to study the sun. The
Aditya-L1 is set to launch
in the early morning hours Saturday -
2:20 AM US Eastern Time (if it doesn't launch that page is likely to say something else by the time you
get to it).
It doesn't need to fly at night because it's not really going to the sun (that
just might be the oldest joke I can remember). The L1 in the mission
name is where it's going: the
L1 Lagrange point
on the sunward side of Earth. Aditya is Sanskrit for sun. The
James Webb Telescope as well the European Euclid telescope are on the opposite
side of the Earth from L1. Since the L1 point always is exposed to the
sun, it's home to NASA's Solar and Heliospheric Observatory Satellite
SOHO. The advantage of observing from L1 (actually an orbit around L1) is there are no lost observation periods due to occultations or eclipses. I should point out that this drawing doesn't seem to show well that L1 and L2 are the same distance from earth, about 932,000 miles.
Image credit to the NASA/WMAP Science Team.
- Study of Solar upper atmospheric (chromosphere and corona) dynamics.
- Study of chromospheric and coronal heating, physics of the partially ionized plasma, initiation of the coronal mass ejections, and flares
- Observe the in-situ particle and plasma environment providing data for the study of particle dynamics from the Sun.
- Physics of solar corona and its heating mechanism.
- Diagnostics of the coronal and coronal loops plasma: Temperature, velocity and density.
- Development, dynamics and origin of CMEs.
- Identify the sequence of processes that occur at multiple layers (chromosphere, base and extended corona) which eventually leads to solar eruptive events.
- Magnetic field topology and magnetic field measurements in the solar corona .
- Drivers for space weather (origin, composition and dynamics of solar wind )
To accomplish these, the probe brings seven instruments.
- Visible Emission Line Coronagraph (VELC)
- Solar Ultraviolet Imaging Telescope (SUIT)
- Solar Low Energy X-ray Spectrometer (SoLEXS)
- High Energy L1 Orbiting X-ray Spectrometer (HEL1OS)
- Aditya Solar wind Particle Experiment (ASPEX)
- Plasma Analyser Package For Aditya (PAPA)
- Advanced Tri-axial High Resolution Digital Magnetometers
The article at SpaceNews.com that got me started researching this mission has much more coverage of the various research targets. After hundreds of years of continually-refined observations, the sun still has lots of mysteries available for study. The first one they mention is what they call the sun's hottest mystery: the corona is much hotter than the surface of the sun although they are in constant contact. The corona can reach 2 million degrees Fahrenheit. The photosphere, around 1,000 miles below it, has an average temperature of around 10,000 degrees F, meaning the sun's outer atmosphere is about 200 times hotter than its surface!
The obstacle to observing the corona from Earth is how much brighter the photosphere is than the corona. It's typically only visible during a total solar eclipse. An alternative that works better in space than on the ground is a corona graph, an instrument on a telescope that blocks out the sun so the corona can be seen. It works better in space because there's no airborne junk to brighten around the image. Or so I've read. Aditya-L1 carries one, the first instrument in that list.
Here's wishing luck to the ISRO and Aditya-L1.