#3: Good vibes for Solar Orbiter
01 April 2019 13:54
Having successfully completed its thermal-vacuum tests in December, Solar Orbiter has been subjected to a new series of arduous environmental tests at the IABG facility in Ottobrunn, Germany, including intense shaking of the spacecraft to ensure that it will survive the stress of launch. 
Solar Orbiter during thermal-vacuum tests. Click here for details and large versions of the video. Credit: Airbus Defence and Space/IABG.
The year began with alignment checks of all the instruments, thrusters and other critical components on the Solar Orbiter Protoflight Model (PFM). This was done to demonstrate the thermal stability of these sensitive components when exposed to the extreme temperature variations and vacuum conditions of deep space. The checks were passed with flying colours.
The spacecraft, in a stowed configuration as it will be within the shroud of the Atlas V launch vehicle, was then built up into a more complete representation of the flight model, prior to the start of the mechanical vibration test campaign.
Two solar arrays were fitted onto the spacecraft. These have been specially designed to ensure they provide sufficient electrical power and survive the intense solar heat, whilst minimising the influence of stray light and build-up of electrical charge on the platform and instruments during Solar Orbiter's close approaches to the Sun.
The instrument boom, fitted with its full suite of scientific instruments, was also integrated to the spacecraft's platform and further reference alignment measurements were carried out.
Now in its full flight configuration, but with all appendages still stowed, the spacecraft went through a number of pre-vibration manual deployment tests. These will be used as a reference for comparison with the final 'live-fire' deployment tests that will be conducted after the vibration test campaign.

Preparations for Solar Orbiter vibration test. Credit: ESA - S. Corvaja
These preliminary tests were completed for the instrument boom and both solar arrays, as well as the high-gain and medium-gain antennas. The manual deployment tests confirmed that no snags could occur during the initial deployment.
Since the various appendages are not designed for deployment under Earth gravity, the procedure required a series of specially designed off-load rigs. These allow near frictionless deployment of the suspended parts, while simulating the weightlessness of space.
To enable each off-load rig to protect the deployable hardware, the spacecraft had to be orientated during each test so that the plane of the deployment was parallel to the ground.
Once the tests were completed, all of the deployed items were re-stowed and small hold-down-and-release devices were attached to them, ready to be fired after completion of the vibration test campaign.
Shaking All Over
The mechanical vibration test phase is designed to confirm and verify the suitability of the spacecraft to survive the lift-off and journey to reach its operational orbits around the Sun. The testing was divided into two parts.
The first of these, the sine vibration test campaign, replicated the powerful thrust of the Atlas V launcher, sudden engine cut-offs and lateral wind shear events throughout the launch and ascent, by mounting the spacecraft on an electro-mechanical shaker.
The sine vibrations were applied separately up to a frequency of 100 Hz in three axes. A series of low-level signature runs was made before and after the main qualifying events, to determine whether the PFM's structural integrity had changed. These proved that the spacecraft was able to survive the heavy shaking to which it was exposed.

Solar Orbiter during preparations for vibration testing. Credit: ESA - S. Corvaja
This mechanical shaking was followed by acoustic tests, which covered the frequency spectrum from just below 100 Hz all the way up to 8 kHz. The largest excitations in the acoustic chamber existed in the approximate range of 100 to 500 Hz.
A number of tests were undertaken as the acoustic noise pressure was steadily increased toward the final qualification levels required by the Solar Orbiter PFM.
Once the major segments of vibration testing were completed, the electrical health of the spacecraft was checked, in order to confirm survivability of all electrical systems.

Preparations for Solar Orbiter vibration test. Credit: ESA - S. Corvaja
After the successful completion of the mechanical vibration tests, the team has re-measured the alignments of all instruments and other critical items. The data demonstrated very good alignment stability, in particular for the remote-sensing optical instruments.
Meanwhile, all the deployable appendages on the spacecraft are being deployed again, using the off-load rigs. This time, however, the various hold-down devices are all being fired to simulate post-launch deployment of both antennas, the solar arrays and the instrument boom. The boom has two phases of deployment, but only the first can be effectively deployed on the ground.
These deployed structures will then be returned to their stowed configuration and the hold-down release mechanisms will be re-commissioned, ready for flight.
A set of measurements of the spacecraft's mass properties in its stowed configuration will also be completed by the end of March. For this, the spacecraft will be mounted on a mass property measurement rig that performs a series of tilt and rotation operations. This determines the inertia, mass and centre of gravity of the spacecraft, characteristics that are important to enable the attitude/orientation control system to control Solar Orbiter's orientation once in space.
Later in the year, a new series of tests is planned to determine the magnetic signature of the spacecraft. These checks will be carried out in a facility that is largely made of non-magnetic materials like wood and aluminium and has a minimum metallic content, enabling the spacecraft's magnetic characteristics to be measured in isolation from external influences.
About Solar Orbiter
Solar Orbiter's mission is to perform unprecedented close-up observations of the Sun. Its unique orbit will allow scientists to study the Sun and its corona in much more detail than previously possible, and to observe specific features for longer periods than can ever be reached by any spacecraft circling the Earth. In addition, Solar Orbiter will measure the solar wind close to the Sun, in an almost pristine state, and provide high-resolution images of the uncharted polar regions of the Sun.
It will carry 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 disk. Other instruments will measure the solar wind and the solar magnetic fields in the vicinity of the orbiter. This will give us unprecedented insight into how our parent star works, and how we can better predict periods of stormy space weather, which are related to coronal mass ejections (CMEs) that the Sun throws our way from time to time.
Scheduled for launch in February 2020, Solar Orbiter will take just under two years to reach its initial operational orbit, taking advantage of gravity-assist flybys of Earth and Venus, and will subsequently enter a highly elliptical orbit around the Sun.
Solar Orbiter is an ESA-led mission with strong NASA participation.

Solar Orbiter ready to depart Europe
18 October 2019
ESA's Solar Orbiter mission has completed its test campaign in Europe and is now being packed ready for its journey to Cape Canaveral at the end of this month, ahead of launch in February 2020. 

Artist's impression of Solar Orbiter. Credit: ESA/ATG medialab

The spacecraft was on display today for the final time in Europe, at the IABG test centre near Munich, Germany. It was built at Airbus Stevenage, UK, and has spent the last year at IABG undergoing essential testing such as checking deployment mechanisms, and that it can withstand the vibrations of launch, and the thermal extremes and vacuum of space. It has now been declared ready for shipment to the launch site and will travel an Antonov cargo plane on 31 October.

Solar Orbiter at IABG. Credit: ESA – S. Corvaja

Once launched it will follow an elliptical path around the Sun, at its closest bringing it within the orbit of Mercury, just 42 million kilometres from the Sun. As such, Sun-facing parts of the spacecraft have to withstand temperatures of more than 500°C – due to solar radiation thirteen times more intense than for Earth-orbiting satellites – while other parts remain in shadow at -180°C.
The mission is essential to learn more about the Sun-Earth connection. We live inside a giant bubble of plasma generated by the Sun that surrounds the entire Solar System, within which we are prey to space weather. Solar Orbiter will provide a deeper understanding as to how activity on the Sun is linked to these solar storms, which can disrupt electrical systems, satellite communications, GPS, and create higher doses of radiation for polar flights and astronauts
"Solar Orbiter is set for answering some of the biggest scientific questions about our star, and its data will help us to better protect our planet from the global challenges of space weather," says Günther Hasinger, ESA Director of Science.
"Thanks to the hard work of our teams building and testing this inspiring space mission, we've reached an important milestone today in Europe, and the spacecraft will now be readied for its final phase of pre-launch preparations at Cape Canaveral."
Solar Orbiter will launch on a NASA-provided Atlas V 411. The launch is currently scheduled in the early hours of 6 February (UTC). Once in space, and over the course of several years, it will use the gravity of Venus and Earth to raise its orbit above the poles of the Sun, providing new perspectives on our star, including the first images of the Sun's polar regions. Its complementary suite of instruments means it will be able to study the plasma environment locally around the spacecraft, and collect data from the Sun from afar, connecting the dots between the Sun's activity, and the space environment in the inner Solar System.
Solar Orbiter is an ESA mission with strong NASA participation. The prime contractor is Airbus Defence and Space in Stevenage, UK. It 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.

The spacecraft will launch at 11:15 p.m. on a United Launch Alliance Atlas V 411 rocket from Space Launch Complex 41 at Cape Canaveral. NASA’s Launch Services Program is managing the launch.

Запуск Solar Orbiter отложен на два дня
Из-за технических проблем, возникших на РН Atlas-5 в ходе наземных испытаний, запуск американо-европейского солнечного зонда Solar Orbiter отложен на двое суток, сообщает SpaceFlightNow. Попытка запуска будет предпринята в ночь на  8февраля с космодрома на мысе Канаверал.
А.Ж.

Спутник Solar Orbiter успешно вышел на орбиту в рамках миссии к Солнцу
       Вашингтон. 10 февраля. ИНТЕРФАКС - Американская ракета-носитель Atlas V в понедельник успешно вывела на орбиту космический аппарат Solar Orbiter для проведения первого в истории исследования полярных областей Солнца, сообщило Национальное управление США по аэронавтике и исследованию космического пространства (NASA).
       В рамках совместного проекта Европейского космического агентства (ESA) и NASA зонд должен выйти на полярную орбиту в 42 млн км от Солнца, то есть ближе, чем находящаяся от нее планета Меркурий.
       Спутник массой 1,8 тонн, стоимость которого оценивается в $1,5 млрд., совершит несколько пролетов вблизи Венеры и один пролет рядом с Землей, чтобы выйти на эллиптическую гелиоцентрическую орбиту Меркурия для последующего изучения полярных областей Солнца.
       При этом космический аппарат будет испытывать интенсивное тепловое излучение, в связи с чем он оснащен особыми щитами из высокотемпературных солнечных панелей.
       Миссия Solar Orbiter продлиться около семи лет. Solar Orbiter начнет проведение исследований уже в мае, однако целевая операция начнется в ноябре 2021.
       Планируется, что космический аппарат проведет в непосредственной близости от Солнца несколько лет, изучая ее поверхность и полярные области.