At the present time ground-based observatories have a wide range of instruments which can study the solar surface in the visible and infrared ranges. But it is not possible to combine these observations with those in the near ultraviolet, which cover the wavelength range from 200 to 400 nanometres, nor to maintain them for long periods due to the turbulence in the Earth’s atmosphere.

In this context, the Sunrise III mission, in which the Instituto de Astrofísica de Canarias (IAC) is collaborating, “has become the first observatory to obtain spectropolarimetric data simultaneously in the near ultraviolet, the visible, and the infrared, with unprecedented spacial and temporal resolution” explains Dr. David Orozco Suárez, staff scientist at the IAA-CSIC, who is the Principal Investigator of the project.

In the coming months, the science team will analyze the data obtained, in order to explain mysteries about the working of our star, which makes life on Earth a possibility. “A preliminary inspection of the data suggests that this mission is revolutionary, with a potential discovery which will mark a turning point in studies of the Sun” adds David Orozco (IAA-CSIC).

The stratospheric mission Sunrise III, which flew successfully from 10th to 16th July of this year, had on board three new instruments, of which one and a half have been developed by the Spanish Aerospatial Solar Physics Network (S3PC). Coordinated by the Solar Physics Group at the Instituto de Astrofísica de Andalucía (IAA-CSIC), the S3PC has designed and built the visible imaging spectropolarimeter TuMag (Tunable Magnetograph) an instrument wihich can measure the solar magnetic field with high precision. 

In addition, in collaboration with a Japanese consortium led by the National Astronomical Observatory of Japan (NAOJ) with Principal Investigator Yuko Ktsukawa, has participated in the development of the SCIP spectorpolarimeter (Sunrise Chromospheric Infrared SpectroPolarimeter), and instrument designed to study the chromosphere, one of the upper layers of the solar atmosphere. The contribution of S3PC to the SCIP comprised its three scientific cameras, the electornics, the control software, and the remote segment. 

The IAC has played a fundamental role in the development of the cameras and of the system to capture images (frame grabber) of the instruments TuMag, and SCIP. Both systems were developed entirely in Spain, within the S3PC. The other institutions which make up the Spanish consortium, as well as the IAA-CSIC and the IAC, are the National Institute of Aerospace Technique (INTA) the Polytechnic University of Madrid (UPM), and the University of Valencia (UV).

Scientific cameras and the frame grabber, developed by the IAC

In the cameras the IAC has contributed the controller of the image sensor, developed with FPGA technology. This controller is notable because it creates and interface, of the type CoaxPress 3.0 which allows the camera to be compeltely managed via a single cable, which greatly simplifies the  integration o the instruments.

The frame-grabber, also developed with PFGA technology, with a major contribution from the IAC, is notable because it integrates functions adapted to the specific needs of the instruments. It guarantees the precise synchronization of the cameras with the optical elements of each instrument, and also incorporates modules to process the images in real time, designed to reduce the size of the scientific data.

“Work which lasts for several years is put to the test during only a few days of flight. We gained great satisfaction when we saw the images arriving at the control centre, and could see that everything was working in its real environment. Also the personal collaboration with the science team during the flight was a very enriching and gratifying experience. Their excitement at the detection of different types of solar events was contagious to the rest of the team” stated David Hernández Expósito, an engineer of the Electronics Department at the IAC.

“This collaboration shows the high level of tehcnology and research in the field of solar physics” pointed out Dr. David Orozco (IAA-CSIC).

A laboratory installed on a balloon

After the scientific importance of its first two experiments, Sunrise III has established itself as a unique mission for investigating the key processes in the lower solar atmosphere, such as the dynamics of its magnetic fields, and the flows of plasma. This processes are essential for understanding solar phenomena which affect the Earth’s environment, including the coronal mass ejections, or the solar storms. On board a stratospheric balloon launched from Sweden and operated at 37 kilometres above the ground, the solar telescope with a 1 metre apertura has permittted observation free from the distortions of the Earth’s atmosphere and access to the near ultraviolet range.

With a six and a half day flight, and a safe landing to the west of Great Bear Lake in Canada, Sunrise III combined the advantages of space-based and ground-based telescopes: a reusable design which allows the improvement and optimization of its instruments for future missions.

A growing scientific legacy

Since their first edition in 2009, the Sunrise missions have generated significant advances in solar physics, with more than 100 scientific publications resulting from the flights. Sunrise III promises to continue this legacy, providing an unprecedented view of the high-altitude stratification of the solar atmosphere, from the deepest layers to the chromosphere.

“The observations taken during the almost seven days of flight have an incalculable scientific value. We are convinced that they will give us very valuable informaton to help understand many physical phenomena that we still don’t understand, and in addition will reveal others about which we know absolutely nothing” states the Principal Investigator of the coordinated project led by the S3PC.

Sunrise III is a collaboration between the Max-Planck-Institut für Sonnensystemforschung, Göttingen (Germany), the main institution, responsible for the telescope and for SUSI, the third instrument, the Applied Physics laboratory of the Johns Hopkins University, Laurel (Maryland USA), in charge of the structure in which the telescope is mounted and of its instruments, the National Astronomical Observatory of Japan, Tokyo, (Japan), the main institution for the SCIP instrument,  Institut für Sonnenphysik of Freiburg (Germany), responsible for the correlation follower, optical system and follower, designed to stabilize the telescope, and the Spanish Aerospatial Solar Physics Network (S3PC).

IRIS-2:the contribution of amateur astronomers.

The Sunrise III aerostatic balloon also carried the IRIS-2 instrument, an imaging and video camera built by a Spanish team made up of amateur astronomers, engineers, and technicians.This instrument follows up on the legacy oof its predecessor, IRIS-1, which flew on Sunrise II in 2013. Its main aim is to offer images for scientific communication and outreach, as well as contributing to the monitoring and improvement of the mechanical interfaces of the control system of the observatory during the whole process, from launch to recovery.

IRIS-2 was of key importance in recording eight and a half hours of video and taking over 16,000 images during the flight. The cameras record in 4K at 20 photograms per second, taking key moments of the launch, the landing, and the release of the balloon. The team managed to record extraordinary details, showing the ability of a group of enthusiastic amateurs and friends in contributing in a valuable way to a mission with such a high scientific level.

REFERENCES:

Web of the S3PC consortium: S3PC

Web of TuMag. (Tunable Magnetograph): https://s3pc.es/TuMag/

MORE INFORMATION

David Hernández Expósito - david.hernandez.exposito [at] iac.es (david[dot]hernandez[dot]exposito[at]iac[dot]es)

VIDEO

Credits: Sunrise/MPS/IRIS-2

SunriseIII_IRIS2_FullFlight.mp4 - Google Drive