After becoming the primary nation to successfully land a spacecraft near the south pole of the moon, India is setting its sights on a brighter goal. The Indian Space Research Organisation (ISRO) will soon launch its first solar observatory, on a mission to analyze some pressing sun mysteries.
The spacecraft, Aditya-L1, is scheduled to launch atop a Polar Satellite Launch Vehicle (PSLV) on Saturday (Sept. 2) at 2:20 a.m. EDT (0620 GMT) from Satish Dhawan Space Centre in Sriharikota, India. You possibly can watch it here on Space.com, courtesy of ISRO.
The launch will send Aditya-L1 into low-Earth orbit. The probe will then engage its propulsion system and head to the Earth-Sun Lagrange Point 1 (hence the L1 a part of the mission’s name; “Aditya” means “sun” in Sanskrit), a gravitationally stable about 1 million miles (1.5 million kilometers) from our planet. From there, Aditya-L1 will have the option to review the sun without interference from eclipses or occultations.
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The mission has many scientific objectives. Its seven instruments are designed to look at the sun’s atmosphere, its surface (often called the photosphere) and the magnetic fields and particles around our star and closer to home.
Some of the intense regions of study for Aditya-L1 will likely be the sun’s upper atmosphere, home to one of the longstanding and troubling mysteries in solar science — the coronal heating problem.
Investigating the sun’s hottest mystery
The corona, manufactured from wispy and nebulous plasma, is of particular interest to solar scientists due to how hot it’s. That may sound like a given. In any case, we’re talking concerning the atmosphere of the sun here.
The problem is that the corona is simply too hot. It’s hotter than the solar surface — far, far hotter. The temperature of the corona can reach 2 million degrees Fahrenheit (1.1 million degrees Celsius), in keeping with NASA. The photosphere, around 1,000 miles (1,600 km) below it, has a median temperature of around 10,000 degrees F (5,500 degrees C), meaning the sun’s outer atmosphere is about 200 times hotter than its surface!
To see why that is so puzzling, imagine a rather less “on the market” example. During a camping trip, you light a campfire, and as you’re toasting marshmallows, you notice that the treats roast faster once you hold them farther from the fireplace. You check and indeed find that the air farther away from the campfire is hotter than the air closer to it. That is akin to what is going on with the corona.
The overwhelming majority of the sun’s heat comes from the nuclear fusion at its core. So, temperatures should increase moving toward the center of our star. And the layers of the sun do conform to this prediction — aside from the corona, and scientists are eager to know why.
Studying the corona is difficult to do here on Earth because photons — particles of sunshine — from the sun’s surface dominate and “wash out” those from the outer atmosphere.
The most effective technique to see the corona from Earth is to attend for a complete solar eclipse, when the disk of the moon obscures the photosphere and the wispy corona is not any longer overpowered. Alternatively, solar scientists can use an instrument called a coronagraph, which attaches to a telescope and replicates this effect.
Aditya-L1 will carry such an instrument, called the Visible Emission Line Coronagraph (VELC). The ISRO probe will even take ultraviolet images of the corona and photosphere using its Solar Ultraviolet Imaging Telescope (SUIT).
Aditya-L1 will do greater than just investigate the coronal heating mystery. The probe will even have a look at solar flares and coronal mass ejections (CMEs), powerful events that may affect life here on Earth.
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Trying out explosive solar weather
CMEs are huge clouds of solar plasma blasted into space when the sun’s magnetic field lines grow to be twisted after which “snap back” into realignment, a process called magnetic reconnection.
This normally occurs in regions of the sun which can be particularly energetic, something that might be indicated by the presence of sunspots. Sunspots, also often called energetic regions, also can give rise to solar flares, that are bursts of electromagnetic radiation that usually accompany CMEs but also can occur independently.
Magnetic reconnection hurls out solar plasma at speeds as great as 7 million mph (11 million kph) — around 4,500 times faster than the highest speed of a jet fighter. Aditya-L1 will search for the mechanisms that drive these solar phenomena, attempting to find processes within the corona and in deeper layers of the sun.
Moreover, the spacecraft will have a look at these events after they’ve traveled away from the sun.
CMEs directed at Earth can reach our planet in as little as 15 to 18 hours, with slower clouds often taking days to achieve us.
Aditya-L1 will study how this plasma changes during its journey from the sun to Earth. It would also make in-situ measurements of the plasma environment near our planet, using its Aditya Solar wind Particle Experiment (ASPEX) and the Plasma Analyser Package For Aditya (PAPA).
The charged particles blasted out by Earth-directed CMEs are channeled down our planet’s magnetic field lines. They then collide with atoms of oxygen and nitrogen in Earth’s upper atmosphere, creating dazzling light shows called auroras over our planet’s poles. But CMEs also can create space weather conditions around Earth that are not quite so pleasing.
For instance, the eruptions can spark powerful geomagnetic storms, which may affect satellites and even communication and power infrastructure here on Earth. So it is vital to grasp space weather and the plasma environment of Earth, scientists say. Also necessary is the understanding of magnetic fields around our planet, which Aditya-L1 will study using its Advanced Tri-axial High-Resolution Digital Magnetometer instrument.
Other sun puzzles for Aditya-L1
Aditya-L1 will even examine coronal loops, massive hoops of plasma that occur when the curved arc of a magnetic field reaches out of the photosphere and channels plasma through it.
These loops extend out for 1000’s of miles, making the sun seem like an enormous, messy ball of plasma yarn.
Coronal loops seem like connected to sunspots; the loops are likely to stretch from one in all these dark patches on the sun and terminate at one other. Scientists aren’t quite sure what the three-dimensional structure of coronal loops is. Some recent research suggests they do not balloon out as much as they need to at high altitudes, indicating that some coronal loops could actually be 2D illusions.
Aditya-L1 will take diagnostics of coronal loops and the plasma that comprises them, measuring their temperature, velocity and density. The spacecraft will even examine the dynamics of the sun’s magnetic field that guide coronal loops.
The probe’s launch follows shortly on the heels of the successful touchdown of India’s Chandrayaan-3 mission, which last week aced the first-ever soft landing near the moon’s south pole.