China opens first solar observatory ASO-S

China launches ASO-S, its first solar exploration mission.

One thing is certain in modern astronomy: one cannot have too many missions to study our host star. This is especially true in 2022, when Solar Cycle #25 gets going in earnest and nears its peak in 2025. China marked last weekend with the launch of its new advanced space-based solar observatory (ASO-S).

The launch took place on Saturday, October 8th^th (Sunday, October 9th^th local time) at 19:43 EDT/23:43 Universal Time (UT) from the Jiuquan Satellite Launch Center in China on board a Long March-2C rocket for China Aerospace and Technology Corporation (CASC). Although China has conducted brief solar experiments on manned Shenzhou missions in the past, ASO-S is the country’s first dedicated solar observing mission.

ASO-S is now listed in the satellite catalog as NORAD ID 2022-129A/54029. The mission is now operational and is in a sun-synchronous orbit 713 by 732 kilometers around the Earth. The Advanced Space-based Solar Observatory (ASO-S) is nicknamed Kuafu-1, after a giant in Chinese lore who tried to chase the sun (pictured on the mission patch). The mission is part of the planned Kuafu project, a triad of space weather satellites.

The 900 million yuan (US$126 million) mission was a long time coming, dating back to the 1976 ASTRON-1 concept. The idea gained traction in 2011 and was formalized in 2017 as part of the Chinese Academy of Sciences’ Strategic Priority Research Program of Space Science, which is analogous to NASA’s Decadal Survey.

A key goal of ASO-S will be to map and understand the relationship between the Sun’s magnetic field and the often energetic emissions it produces. With a nominal mission of four years, scientists hope that bridging the peak of solar cycle #25 should provide plenty of opportunities to see a plethora of solar flares. ASO-S is also unique in that it will see the poorly understood “middle corona” region along the entire UV-ultraviolet spectrum.

Observations provided by ASO-S will also complement ESA’s Solar Orbiter and NASA’s Parker Solar Orbiter. These contrasting perspectives could provide stereoscopic views of flares from heliocentric versus geocentric perspective. This, in turn, could help solve the mystery of “directivity,” or how intensely solar flares tend to flow in a particular path.

To accomplish this, ASO-S carries a trio of instruments: a sun-blocking coronagraph that will study the corona in the ultraviolet to visible range, a magnetograph to cover the Sun’s magnetic field, and an X-ray imager to study high-energy outbursts in powerful solar flares. These instruments will be combined to allow simultaneous observations during solar events.

A unique solar mission

To this end, ASO-S is observing “the two most purple phenomena on the Sun – solar flares and CMEs – to observe their formation, evolution, interaction and relationships,” said Mission Director Dr. Said by Weigun Gan from the Purple Mountain Observatory in Nanjing, China universe today. “With such properties, ASO-S is particularly well suited to study the relationships between the Sun’s magnetic field, solar flares and coronal mass ejections (CMEs).”

Next, ASO-S will undergo a three to six month in-orbit commissioning phase. Look out for the mission to make images of the Sun available to the public on a daily basis once startup and checkout is complete.

“Once the go-live phase is complete, all data and software will be opened up to the community,” says Gan.

Solar Cycle 25 is shaping up to be the best-studied solar cycle in history: in addition to ground-based observatories, space-facing missions include: NASA’s Solar Dynamics Observatory, Japan’s Hinode, ESA’s Proba-2, the joint ESA/NASA SOHO mission , the Parker Solar Probe, STEREO-A and ESA’s Solar Orbiter.

ASO-S/Kuafu-1 will be kept in mind as we unravel our host star’s mysteries.