Company for Aditya-L1: Here are solar missions of other space agencies

USA

National Aeronautics and Space Administration (NASA), the US space agency, launched the Parker Solar Probe in August 2018. It was the culmination of decades of development to craft a robotic explorer able to withstand the heat and radiation near the Sun like no other spacecraft before it.

Parker Solar Probe was developed as part of NASA’s “Living With a Star” programme to explore aspects of the Sun-Earth system that directly affect life and society. Since 2018, it has been exploring the origins and unlocking the secrets of the solar wind and other properties of the near-Sun environment at their source.

In December 2021, Parker flew through the Sun's upper atmosphere, the corona, and sampled particles and magnetic fields there. This was the first time ever that a spacecraft “touched the Sun”, according to NASA's official website.

The spacecraft has returned more than twice the amount of data that scientists expected, making discoveries critical to understanding the source and properties of the solar wind. On June 27, 2023, the spacecraft completed its 16^th orbit of the sun, out of 24 planned during the primary mission.

Each winter, the Geminid meteors light up the sky as they race past Earth, producing one of the most intense meteor showers in the night sky. Now, the Parker Solar Probe mission is providing new evidence that a violent, catastrophic event created the Geminids.

During the perihelion, the spacecraft travelled at 364,619 miles per hour, fast enough to fly from New York to Tokyo in just over a minute, according to NASA’s blog.

The Parker Solar Probe will be moving 394,742 miles per hour when it comes within just 4.5 million miles from the Sun’s surface – breaking its own record for speed and solar distance – on September 27, 2023.

Other active solar missions by the NASA are Advanced Composition Explorer launched in August, 1997; Solar Terrestrial Relations Observatory in October, 2006; Solar Dynamics Observatory in February, 2010; and Interface Region Imaging Spectrograph launched in June, 2013.

Japan

JAXA, the Japan's space agency, launched its first solar observation satellite, Hinotori (ASTRO-A), in 1981. The objective was to study solar flares, solar particle rays, X-ray bursts, etc., using 2D data in hard X-rays, according to JAXA's official website.

The satellite also provided observational data to the international project on the maximum period of solar activity. The agency was able to discover several new facts including high-temperature phenomena reaching up to 50 million °C and clouds of light-speed electrons floating in coronas.

The main objectives of Yohkoh, launched in 1991, were observation of solar flares during maximum period of solar activity and observation of physical phenomena of solar coronas related to solar flares. The obtained data has revealed that solar coronas change their structure dynamically at various time-scales and that explosive phenomena such as flares are in fact "magnetic reconnection" phenomena in the corresponding coronas.

Europe

In October, 1990, the European Space Agency (ESA) launched Ulysses to study the environment of space above and below the poles of the Sun.

The ESA launched Proba-2 in October, 2001. Proba stands for PRoject for On-Board Autonomy. Proba-2 is the second of the Proba series, building on nearly eight years of successful Proba-1 experience, even as Proba-1 was not a solar exploratory mission.

The Proba satellites are the smallest-ever flown by the ESA.

On-board Proba-2 were four experiments, two of them solar observation experiments.

The two solar observation experiments are a Large Yield Radiometer (LYRA) that will monitor four bands in a very wide ultraviolet spectrum, and an extreme-ultraviolet telescope (SWAP) using new pixel sensor technology (APS), that will make measurements of the solar corona in a very narrow band.

China

The Advanced Space-based Solar Observatory (ASO-S) was successfully launched by National Space Science Center, Chinese Academy of Sciences (CAS), on October 8, 2022.

The primary scientific objectives of the ASO-S are to study the solar magnetic field and the two most violent eruptions on the Sun – solar flares and coronal mass ejections (CMEs) - and to observe and study their formation, evolution, interaction, and mutual relevance.

Joint space missions

The Solar Orbiter

In February 2020, NASA joined hands with the ESA and launched The Solar Orbiter to collect data to find out how the Sun created and controlled the constantly-changing space environment throughout the solar system.

The mission objectives of the Solar Orbiter are to take the closest-ever images of the Sun, the first ever close-up images of the Sun’s polar regions, measuring the composition of the solar wind and linking it to its area of origin on the Sun’s surface.

According to the ESA’s website, scientists hope to find answers to some profound questions: What drives the Sun’s 11-year cycle of rising and subsiding magnetic activity? What heats up the upper layer of its atmosphere, the corona, to millions of degrees Celsius? What drives the generation of the solar wind? What accelerates the solar wind to speeds of hundreds of kms per second? And how does it all affect our planet?

SOHO

In December, 1995, NASA, ESA and JAXA jointly launched the Solar and Heliospheric Observatory (SOHO).

Stationed 1.5 million kms away from Earth, SOHO constantly watches the Sun, returning spectacular pictures and data of the storms that rage across its surface. SOHO's studies range from the Sun's hot interior, through its visible surface and stormy atmosphere, and out to distant regions where the wind from the Sun battles with a breeze of atoms coming from among the stars.

Hinode

In 2006, Hinode (SOLAR-B) was launched, which was the successor to Yohkoh (SOLAR-A), the orbiting solar observatory. Japan launched it in collaboration with the US and the UK. The objective of Hinode, an observatory satellite, is to study the impact of the Sun on the Earth.

(With agency inputs)