posted 02-08-2020 05:31 PM               

Solar Orbiter

Solar Orbiter's mission is to perform unprecedented close-up observations of the Sun and from high-latitudes, providing the first images of the uncharted polar regions of the Sun, and investigating the Sun-Earth connection.

The spacecraft carries 10 state-of-the-art instruments. Remote sensing payloads will perform high-resolution imaging of the Sun's atmosphere – the corona – as well as the solar disc. Other instruments will measure the solar wind and the solar magnetic fields in the vicinity of the orbiter. This will provide unprecedented insight into how our parent star works in terms of the 11-year solar cycle, and how we can better predict periods of stormy space weather.

Solar Orbiter will take just under two years to reach its initial operational orbit, taking advantage of gravity-assist flybys of Earth and Venus to enter a highly elliptical orbit around the Sun.

Solar Orbiter follows in the legacy of missions such as Ulysses (1990-2009) and SOHO (1995-present) and will also provide complementary datasets to NASA's Parker Solar Probe that will allow more science to be distilled from the two missions than either could achieve on their own.

Exploring the Sun

Solar Orbiter will address big questions in space science to help us understand how our star creates and controls the giant bubble of plasma – the heliosphere – that surrounds the whole Solar System and influences the planets within it. It will concentrate on four main areas of investigation; very broadly:

• Solar wind: What drives the solar wind and the acceleration of solar wind particles?
  
• Polar regions: What happens in the polar regions when the solar magnetic field flips polarity?
  
• Magnetic field: How is magnetic field generated inside the Sun and how does it propagate through the Sun's atmosphere and outwards into space?
  
• Space weather: How do sudden events like flares and coronal mass ejections impact the Solar System, and how do solar eruptions produce the energetic particles that lead to extreme space weather at Earth?

Operating in extreme environments

Solar Orbiter must operate for years in one of the most hostile regions of the Solar System. At closest approach, approximately 42 million kilometres from the Sun, it will be at just over a quarter of the distance between the star and our planet, well inside the orbit of inner planet Mercury. This close to the Sun, the spacecraft will be exposed to sunlight 13 times more intense than what we feel on Earth. The spacecraft must also endure powerful bursts of particle radiation from explosions in the solar atmosphere.

The spacecraft's heatshield is key to making this mission possible, which can withstand temperatures of 500 degrees Celsius [932 degrees Fahrenheit]. Small sliding doors with heat resistant windows let sunlight in to the science instruments located directly behind the protective heatshield.

Operations

Solar Orbiter will communicate with Earth via ESA's deep space tracking network, ESTRACK. All operations are conducted by the European Space Operations Centre (ESOC) in Darmstadt, Germany. The Science Operations Centre located at ESA's European Space Astronomy Centre, ESAC, in Villanueva de la Cañada, Spain, will be responsible for science operations planning, and for archiving the mission's data for scientists to use.

Partners

Solar Orbiter is a space mission of international collaboration between ESA and NASA. The spacecraft has been developed by Airbus. Numerous industrial partners and scientific institutes across ESA Member States and the US have contributed to the construction of the spacecraft and the scientific instruments.

posted 02-08-2020 05:33 PM               

United Launch Alliance Set to Launch Solar Orbiter for NASA and ESA

A United Launch Alliance (ULA) Atlas V rocket is in final preparations to launch the Solar Orbiter mission, an international cooperative mission between the European Space Agency (ESA) and NASA. The launch is on track for Feb. 9, 2020 at Space Launch Complex-41 from Cape Canaveral Air Force Station.

Launch is planned for 11:03 p.m. EST (0403 GMT Feb. 10) at the opening of a two-hour launch window.

Solar Orbiter will leave the launch pad atop 1.2 million pounds of thrust from the Atlas V main engine and single solid rocket booster (SRB). The SRB will burn for about 90 seconds while the first stage engine will burn for four minutes. Two burns by the Centaur upper stage achieve escape velocity, propelling Solar Orbiter to 27,000 mph for deployment less than an hour after liftoff.

The Atlas V 411 rocket, a unique configuration that includes just one solid rocket booster, provides the optimal performance to precisely deliver a range of mission types. In its nearly 14 years of service, the 411 rocket has completed five flights, including NASA's OSIRIS-REx mission. With a distinctive appearance, the Atlas V 411 is tailored to the performance needed to achieve the Earth departure trajectory for making repeated close encounters to the sun. This configuration first launched on April 20, 2006.

"We are proud to launch Solar Orbiter in support of our NASA and international mission partners," said Gary Wentz, ULA vice president of Government and Commercial Programs. "This exciting mission will allow us to further explore our universe and understand the intricacies of the sun."

This Atlas V 411 configuration vehicle includes a 4-meter large payload fairing (PLF) and stands 189 ft. tall. The Atlas booster for this mission is powered by the RD AMROSS RD-180 engine. Aerojet Rocketdyne provided the one AJ-60A SRB and RL10A-4-2 engine for the Centaur upper stage. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida selected ULA's proven Atlas V vehicle for this mission and is responsible for management and oversight of the Atlas V launch services.

posted 02-08-2020 05:35 PM               

Solar Orbiter, a collaboration between European Space Agency and NASA, is launching Sunday, Feb. 9, to study the inner workings of our nearest star. Tune in for launch coverage starting at 10:30 p.m. on Sunday, Feb. 9 [0330 GMT Feb. 10] to see liftoff, currently targeted for 11:03 p.m. EST [0403 GMT Feb. 10].

posted 02-10-2020 08:05 AM               

Liftoff for Solar Orbiter, ESA's mission to face the Sun up close

ESA's Solar Orbiter mission lifted off on an Atlas V 411 from Cape Canaveral, Florida, at 05:03 CET on 10 February [11:03 p.m. EST on Feb. 9] on its mission to study the Sun from new perspectives.

Signals from the spacecraft were received at New Norcia ground station at 06:00 CET, following separation from the launcher upper stage in low Earth orbit.

Facing the Sun

Solar Orbiter, an ESA-led mission with strong NASA participation, will provide the first views of the Sun's uncharted polar regions, giving unprecedented insight into how our parent star works.

It will also investigate how intense radiation and energetic particles being blasted out from the Sun and carried by the solar wind through the Solar System impact our home planet, to better understand and predict periods of stormy 'space weather'. Solar storms have the potential to knock out power grids, disrupt air traffic and telecommunications, and endanger space-walking astronauts, for example.

"As humans, we have always been familiar with the importance of the Sun to life on Earth, observing it and investigating how it works in detail, but we have also long known it has the potential to disrupt everyday life should we be in the firing line of a powerful solar storm," says Günther Hasinger, ESA Director of Science.

"By the end of our Solar Orbiter mission, we will know more about the hidden force responsible for the Sun's changing behavior and its influence on our home planet than ever before."

"Solar Orbiter is going to do amazing things. Combined with the other recently launched NASA missions to study the Sun, we are gaining unprecedented new knowledge about our star," said Thomas Zurbuchen, NASA's associate administrator for Science at the agency's headquarters in Washington.

"Together with our European partners, we're entering a new era of heliophysics that will transform the study of the Sun and help make astronauts safer as they travel on Artemis program missions to the Moon."

At its closest, Solar Orbiter will face the Sun from within the orbit of Mercury, approximately 42 million kilometers from the solar surface. Cutting-edge heatshield technology will ensure the spacecraft's scientific instruments are protected as the heatshield will endure temperatures of up to 500 degrees C – up to 13 times the heat experienced by satellites in Earth orbit.

"After some twenty years since inception, six years of construction, and more than a year of testing, together with our industrial partners we have established new high-temperature technologies and completed the challenge of building a spacecraft that is ready to face the Sun and study it up close," adds César García Marirrodriga, ESA's Solar Orbiter project manager.

New perspectives on our parent star

Solar Orbiter will take just under two years to reach its initial operational orbit, making use of gravity-assist flybys of Earth and Venus to enter a highly elliptical orbit around the Sun. The spacecraft will use the gravity of Venus to slingshot itself out of the ecliptic plane of the Solar System, which is home to the planetary orbits, and raise its orbit's inclination to give us new views of the uncharted polar regions of our parent star.

The poles are out of view from Earth and to other spacecraft but scientists think they are key to understanding the Sun's activity. Over the course of its planned five-year mission, Solar Orbiter will reach an inclination of 17 degrees above and below the solar equator. The proposed extended mission would see it reach up to 33 degree inclination.

"Operating a spacecraft in close proximity of the Sun is an enormous challenge," says Sylvain Lodiot, ESA's Solar Orbiter spacecraft operations manager.

"Our team will have to ensure the continuous and accurate pointing of the heatshield to avoid the potential damage from the Sun's radiation and thermal flux. At the same time, we will have to ensure a rapid and flexible response to the requests of the scientists to adapt their instruments' operations according to the most recent observations of the Sun surface."

Solar Orbiter will use a combination of 10 in situ and remote-sensing instruments to observe the turbulent solar surface, the Sun's hot outer atmosphere and changes in the solar wind. Remote-sensing payloads will perform high-resolution imaging of the Sun's atmosphere – the corona – as well as the solar disc. In situ instruments will measure the solar wind and the solar magnetic field in the vicinity of the orbiter.

"The combination of remote-sensing instruments, which look at the Sun, and in situ measurements, which feel its power, will allow us to join the dots between what we see at the Sun and what we experience while soaking up the solar wind," says Daniel Müller, ESA's Solar Orbiter project scientist.

"This will provide unprecedented insight into how our parent star works in terms of its 11-year solar activity cycle, and how the Sun creates and controls the magnetic bubble – the heliosphere – in which our planet resides."

We are all Solar Orbiters

Solar Orbiter will be one of two complementary spacecraft studying the Sun at close proximity: it will join NASA's Parker Solar Probe, which is already engaged in its mission.

Solar Orbiter and Parker Solar Probe have each been designed and placed into a unique orbit to accomplish their different, if complementary, goals. Parker Solar Probe 'touches' our star at much closer distances than Solar Orbiter, to study how the solar wind originates – but does not have cameras to view the Sun directly. Solar Orbiter flies at an ideal distance to achieve a comprehensive perspective of our star, including both remote images and in situ measurements, and will view the Sun's polar regions for the first time.

Beyond accomplishing its own science goals, Solar Orbiter will provide contextual information to improve the understanding of Parker Solar Probe's measurements. By working together in this way, the two spacecraft will collect complementary data sets that will allow more science to be distilled from the two missions than either could manage on its own.

"Solar Orbiter is the newest addition to the NASA Heliophysics System Observatory, joining Parker Solar Probe in an extraordinary adventure to unlock the biggest mysteries of the Sun and its extended atmosphere," says Holly Gilbert, NASA Solar Orbiter Project Scientist.

"The powerful combination of these two missions and their awe-inspiring technology advancements will thrust our understanding to new heights."

Solar Orbiter is set to build on the legacy of missions such as the joint ESA/NASA Ulysses and Solar and Heliophysics Observatory (SOHO), to give us the most advanced look yet at our star, and its influence on Earth.

posted 07-16-2020 08:35 AM               

Solar Orbiter's first images reveal 'campfires' on the Sun

The first images from Solar Orbiter, a new Sun-observing mission by ESA and NASA, have revealed omnipresent miniature solar flares, dubbed 'campfires', near the surface of our closest star.

According to the scientists behind the mission, seeing phenomena that were not observable in detail before hints at the enormous potential of Solar Orbiter, which has only just finished its early phase of technical verification known as commissioning.

Above: First views of the Sun obtained with Solar Orbiter's EUI on 30 May 2020, revealing the omnipresent miniature eruptions dubbed "campfires."

"These are only the first images and we can already see interesting new phenomena," says Daniel Müller, ESA's Solar Orbiter Project Scientist. "We didn't really expect such great results right from the start. We can also see how our ten scientific instruments complement each other, providing a holistic picture of the Sun and the surrounding environment."

Solar Orbiter, launched on 10 February 2020, carries six remote-sensing instruments, or telescopes, that image the Sun and its surroundings, and four in situ instruments that monitor the environment around the spacecraft. By comparing the data from both sets of instruments, scientists will get insights into the generation of the solar wind, the stream of charged particles from the Sun that influences the entire Solar System.

The unique aspect of the Solar Orbiter mission is that no other spacecraft has been able to take images of the Sun's surface from a closer distance.

Closest images of the Sun reveal new phenomena

The campfires shown in the first image set were captured by the Extreme Ultraviolet Imager (EUI) from Solar Orbiter's first perihelion, the point in its elliptical orbit closest to the Sun. At that time, the spacecraft was only 77 million km away from the Sun, about half the distance between Earth and the star.

"The campfires are little relatives of the solar flares that we can observe from Earth, million or billion times smaller," says David Berghmans of the Royal Observatory of Belgium (ROB), Principal Investigator of the EUI instrument, which takes high-resolution images of the lower layers of the Sun's atmosphere, known as the solar corona. "The Sun might look quiet at the first glance, but when we look in detail, we can see those miniature flares everywhere we look."

The scientists do not know yet whether the campfires are just tiny versions of big flares, or whether they are driven by different mechanisms. There are, however, already theories that these miniature flares could be contributing to one of the most mysterious phenomena on the Sun, the coronal heating.

Unravelling the Sun's mysteries

Above: One of the newly found campfires in an image from Solar Orbiter's EUI. The circle in the lower left corner indicates the size of Earth for scale.

"These campfires are totally insignificant each by themselves, but summing up their effect all over the Sun, they might be the dominant contribution to the heating of the solar corona," says Frédéric Auchère, of the Institut d'Astrophysique Spatiale (IAS), France, Co-Principal Investigator of EUI.

The solar corona is the outermost layer of the Sun's atmosphere that extends millions of kilometres into outer space. Its temperature is more than a million degrees Celsius, which is orders of magnitude hotter than the surface of the Sun, a 'cool' 5500 °C. After many decades of studies, the physical mechanisms that heat the corona are still not fully understood, but identifying them is considered the 'holy grail' of solar physics.

"It's obviously way too early to tell but we hope that by connecting these observations with measurements from our other instruments that 'feel' the solar wind as it passes the spacecraft, we will eventually be able to answer some of these mysteries," says Yannis Zouganelis, Solar Orbiter Deputy Project Scientist at ESA.

Seeing the far side of the Sun

The Polarimetric and Helioseismic Imager (PHI) is another cutting-edge instrument aboard Solar Orbiter. It makes high-resolution measurements of the magnetic field lines on the surface of the Sun. It is designed to monitor active regions on the Sun, areas with especially strong magnetic fields, which can give birth to solar flares.

During solar flares, the Sun releases bursts of energetic particles that enhance the solar wind that constantly emanates from the star into the surrounding space. When these particles interact with Earth's magnetosphere, they can cause magnetic storms that can disrupt telecommunication networks and power grids on the ground.

"Right now, we are in the part of the 11-year solar cycle when the Sun is very quiet," says Sami Solanki, the director of the Max Planck Institute for Solar System Research in Göttingen, Germany, and PHI Principal Investigator. "But because Solar Orbiter is at a different angle to the Sun than Earth, we could actually see one active region that wasn't observable from Earth. That is a first. We have never been able to measure the magnetic field at the back of the Sun."

Above: The Sun and its magnetic properties observed by the PHI instrument on Solar Orbiter.

The magnetograms, showing how the strength of the solar magnetic field varies across the Sun's surface, could be then compared with the measurements from the in situ instruments.

"The PHI instrument is measuring the magnetic field on the surface, we see structures in the Sun's corona with EUI, but we also try to infer the magnetic field lines going out into the interplanetary medium, where Solar Orbiter is," says Jose Carlos del Toro Iniesta, PHI Co-Principal Investigator, of Instituto de Astrofísica de Andalucía, Spain.

Catching the solar wind

The four in situ instruments on Solar Orbiter then characterise the magnetic field lines and solar wind as it passes the spacecraft.

Christopher Owen, of University College London Mullard Space Science Laboratory and Principal Investigator of the in situ Solar Wind Analyser, adds, "Using this information, we can estimate where on the Sun that particular part of the solar wind was emitted, and then use the full instrument set of the mission to reveal and understand the physical processes operating in the different regions on the Sun which lead to solar wind formation."

"We are all really excited about these first images – but this is just the beginning," adds Daniel. "Solar Orbiter has started a grand tour of the inner Solar System, and will get much closer to the Sun within less than two years. Ultimately, it will get as close as 42 million km, which is almost a quarter of the distance from Sun to Earth."

"The first data are already demonstrating the power behind a successful collaboration between space agencies and the usefulness of a diverse set of images in unravelling some of the Sun's mysteries," comments Holly Gilbert, Director of the Heliophysics Science Division at NASA Goddard Space Flight Center and Solar Orbiter Project Scientist at NASA.