Astronomie - Startvorbereitung für ESA Solar Orbiter Proba-3 Mission -Update





Proba-3 formation flying satellites
22 August 2016

Every 18 months or so, scientists and sensation-seekers gather at set points on Earth’s surface, to await awe-inspiring solar eclipses. The Moon briefly blocks the Sun, revealing its mysterious outer atmosphere, the corona. Though what if researchers could induce such eclipses at will?

That’s the scientific vision behind ESA’s double-satellite Proba-3, the world’s first precision formation-flying mission, planned for launch in 2019.

An ‘occulter’ satellite will fly 150 m ahead of a second ‘coronagraph’ satellite, casting a precise shadow to reveal the ghostly tendrils of the solar corona, down to 1.2 solar radii, for hours on end.

“We have two scientific instruments aboard,” explains Damien Galano, Proba-3 Payload Manager. “The primary payload is ASPIICS, a coronagraph to observe the corona in visible light while the DARA radiometer on the occulter measures the total solar irradiance coming from the Sun – a scientific parameter about which there is still some uncertainty. 

Proba-3 revealing corona

“The corona is a million times fainter than the Sun itself, so the light from the solar disk needs to be blocked in order to see it. The coronagraph idea was conceived by astronomer Bernard Lyot in the 1930s – and since then has been developed and has been incorporated into both Earth-based and space telescopes.

“But because of the wave nature of light, even within the cone of shadow cast by the occulter, some light still spills around the occulter edges, a phenomenon called ‘diffraction’.

“To minimise this unwanted light, the coronagraph can be positioned closer to the occulter – and therefore deeper into the shadow cone. However the deeper it is, the more the solar corona will also be occulted by the occulter. 

Coronagraph on single satellite

“Hence the advantage of a larger occulter and the maximum possible distance between the occulter and the coronagraph. Obviously a 150-m-long satellite is not a practical proposition, but our formation flying approach should provide us with equivalent performance.

“Furthermore, the ASPIICS coronagraph itself contains a smaller, secondary occulter disk, to cut down on diffracted light still further.

Coronagraph across two satellites

“Precision is all – the aperture of the ASPIICS instrument measures 50 mm in diameter, and for corona observation performance it should remain as much as possible in the centre of the shadow, which is about 70 mm across at 150 m.

"So we’ll need to achieve millimetre-scale positioning control between the two spacecraft, effectively forming a single giant instrument across space.”

ASPIICS (Association of Spacecraft for Polarimetry and Imaging of the Corona of the Sun) is being developed for ESA by a consortium led by Centre Spatial de Liège in Belgium, made up of 15 companies and institutes from five ESA Member States.

Diffraction of light

“Many of these companies are new to ESA, and they’ve proved to be very motivated and eager to show their capabilities,” remarks Damien. “We’ve produced various prototypes of instrument elements, and our first complete ‘structural and thermal model’ should be complete in the autumn, ahead of our end-of-year Critical Design Review.

“We’re also looking into various optical aspects, such as the best occulter edge shape to minimise diffraction.”

There’s a lot of broader interest in this external occulter approach – especially for the imaging of Earth-like exoplanets, which would require the blocking out of their parent stars.

“It’s a similar challenge, the main difference being that the star in question is a point source of light rather than the extended source that our Sun is.

“So it could be that formation-flown external occulters become versatile scientific tools, opening many new vistas in astronomy.”

Quelle: ESA


Update: 13.09.2016


Proba-3 satellites form artificial eclipse


By converging in orbit, a pair of small satellites will open a new view on the source of the largest structure in the Solar System: the Sun’s ghostly atmosphere, extending millions of kilometres out into space.

The two satellites together are called Proba-3, set for launch in late 2019. Through precise formation flying, one will cast a shadow across the second to open up an unimpeded view of the inner area of the ‘corona’, which is a million times fainter than the blindingly brilliant solar disc.

“When I first heard of the idea I said ‘Wow! That’s just what we need’,” said Andrei Zhukov of the Royal Observatory of Belgium, serving as Principal Investigator for Proba-3’s solar instrument.

“The best way to observe the corona from the ground is during a solar eclipse, although we still have to cope with stray light – we cannot correct for the influence of Earth’s atmosphere. 

Solar eclipses
Solar corona seen during terrestrial eclipses

“The next best method is by using ‘coronagraphs’ to create an articifical eclipse, either on ground telescopes or inside Sun-watching satellites such as SOHO and Stereo.

“The problem is that stray light bending around the edge of the occulting disc limits our view of the most important inner portion of the corona. SOHO’s coronagraph, for instance, can observe no closer in than 1.1 Sun-diameters. Others can see closer, but with strong stray light making detailed observation impossible.

“With Proba-3 we aim to see extremely close to the solar surface in visible light, by flying the occulter and coronagraph on separate satellites some 150 m apart.

A fiery solar explosion 

“This should give us a ringside seat on the most interesting segment of the corona, where a lot of interesting physics is going on, where the solar wind is born and ‘coronal mass ejections’ originate – gigantic solar eruptions with the potential to affect our terrestrial infrastructure.”

While the Sun’s surface is a comparatively cool 6000ºC, the corona averages a sizzling million degrees. The mystery is how energy travels from the cool Sun to the hot corona, in apparent defiance of the laws of thermodynamics.

“By mapping the fine structure of the inner corona for a prolonged time – we are targeting around six hours – our hope is that we gain insight into the kind of energy flows that are taking place,” notes Dr Zhukov. 

Proba-3's pair of satellites

“Our standard observing mode will be once per minute, but we could speed that up to a few seconds within a selected field of view, for instance when tracing the rapid evolution of a mass ejection.

“The ultimate goal is to be able to solve the physics of space weather, in order to forecast coronal mass ejections, which are known to have dramatic effects on terrestrial electricity grids and other infrastructure.”

Proba-3 is first and foremost a technology demonstration, exploring the potential of precise formation flying in orbit, but achieving meaningful scientific results will also help to prove its approach works.

Quelle: ESA


Update: 20.08.2017


Pioneering ESA mission aims to create artificial solar eclipses

Due to launch together in 2020, the two satellites making up Proba-3 will fly in precise formation to form an external coronagraph in space, one satellite eclipsing the sun to allow the second to study the otherwise invisible solar corona. Credit: ESA

As skywatchers and scientists converge on a transcontinental band of totality for Monday’s solar eclipse in the United States, engineers in Europe are building a unique pair of satellites to create artificial eclipses lasting for hours — a feat that that could be a boon for solar physicists but will escape the view of Earth-bound spectators.

The European Space Agency’s Proba-3 mission, scheduled for launch in late 2020, is made possible by two satellites, one about the size of a refrigerator, and another slightly smaller spacecraft with the rough dimensions of a coffee table.

The basic idea is to fly the smaller satellite directly between the sun and the field-of-view of cameras and instruments mounted on the bigger spacecraft, blocking the sunlight and revealing the glow of the sun’s corona, or super-hot atmosphere, and filament-like eruptions called solar flares.

The light coming from the surface of the sun is a million times brighter than the corona, requiring special measures to see the solar atmosphere.

The concept of obstructing the brightest light emanating from the sun to study activity around it is not new. Scientists have made observations of the corona for centuries during solar eclipses, and there are other space missions that carry coronagraphs, light-blocking discs buried inside telescopes used to make the relatively dim solar atmosphere visible.

But coronagraphs mounted inside telescopes are prone to stray light, a common problem in optics. Light escaping around the coronagraph disc can distort or mask views of the corona.

One simple way to think of the stray light problem is to compare an image of a total solar eclipse, a spectacular phenomenon where the faint corona suddenly springs into view. Holding your thumb over the sun at arm’s length does not produce the same result because sunlight has already been scattered by particles in Earth’s atmosphere.

“One of the science goals of Proba-3 is to reproduce the conditions of a total solar eclipse as much as possible,” said Andrei Zhukov, principal investigator for Proba-3’s coronagraph at the Royal Observatory of Belgium, in response to questions from Spaceflight Now.

Artist’s concept of an artificial eclipse created by the Proba-3 mission. Credit: ESA – P. Carril, 2013

In general, the longer the distance between an observer or a camera and the object obscuring the sun, the better the result. Scientists also do not have to worry about atmospheric distortions in space.

“This problem can be minimized by extending the coronagraph length, the distance between the camera and the disc, as far as possible – but there are practical limits to coronagraph size,” Zhukov said in an ESA press release.

“Instead, Proba-3’s coronagraph uses two craft: a camera satellite and a disc satellite,” Zhukov said. “They fly together so precisely that they operate like a single coronagraph, 150 meters (492 feet) long.”

The duo will launch together into an highly elliptical, oval-shaped orbit around Earth taking the satellites as high as 37,611 miles (60,530 kilometers) and as low as 372 miles (600 kilometers).

In that orbit, the satellites will complete one lap around the planet every 19.6 hours. For six of those hours, cameras on Proba-3’s larger satellite will have an artificial eclipse.

Proba-3 will see the features down to 34,500 miles (55,600 kilometers) from the sun — about 8 percent of the solar radius — resolving activity closer to the solar limb than any current space mission. Zhukov said ground-based observers looking at a total solar eclipse can still see more of the corona than Proba-3, but the advantage of a space mission is the eclipse’s longevity.

“During two years of its nominal mission, Proba-3 will provide around 1,000 hours of coronal observations,” Zhukov wrote in an email to Spaceflight Now. “This has to be compared with several minutes of duration of ‘natural’ eclipses during the same time.

“Proba-3 will also be free from disturbances produced by the Earth’s atmosphere in all astronomical observations,” Zhukov wrote.

ESA is developing the Proba-3 mission as an experimental demonstration, with scientific observations of the sun a secondary goal.

Engineers want to test out technologies for autonomous formation flying on Proba-3, which will use ranging measurements with the help of GPS navigation signals and optical sensors.

The two spacecraft will be connected with an inter-satellite radio link, and the so-called occulter satellite — the smaller of the pair — will carry low-power micro-thrusters for fine maneuvers, keeping the two vehicles positioned with millimeter precision.

Proba-3 will create an eclipse when the satellites are farthest from Earth. The satellites will passively drift apart during the rest of each orbit, a fuel-saving measure to minimize consumption of the mission’s limited supply of propellant.

The capabilities to be proved out on Proba-3 could be used on future missions to repair satellites in orbit or return samples from Mars, according to ESA.

Already approved for development as a tech demo mission, Proba-3 won the backing of ESA’s science program committee earlier this year. The agency’s scientific division will pay for Proba-3’s science operations center to ensure astronomers get the most out of the project.

Proba-3 was scheduled for launch in 2019, but officials recently pushed back the mission’s liftoff to the fourth quarter of 2020.

“The complexity in the development of the formation flying technology does not allow the launch in late 2019 as was planned earlier,” Zhukov said. “The project schedule is now consolidated, and the launch in the fourth quarter of 2020 is the new baseline. That does look feasible.”

Quelle: SN


Update: 28.08.2017


Solar Orbiter on track to launch before next total solar eclipse


Stevenage, 21/08/2017 - Today’s total Solar Eclipse across the United States of America will provide a spectacular view of the mysterious Solar Corona, the one million degree “halo” around the sun, which can only be seen from Earth when the Moon passes in front of the bright solar disk, which otherwise completely drowns out the faint light of the corona.

Scientists lucky enough to be able to see the Solar Eclipse from Earth will be studying this rare glimpse of the corona during the one hundred and sixty seconds or less that the eclipse lasts, to try to answer the many unanswered questions about this mysterious corona. Noone yet knows for instance, why the corona is more than 100 times hotter than the surface of the Sun.

Meanwhile the European Space Agency spacecraft Solar Orbiter is in the final stages of spacecraft integration at the Airbus spacecraft assembly hall in Stevenage, UK.

Solar Orbiter will be launched in February 2019 into a close orbit around the Sun and will allow scientists to study the solar corona in much more detail, for much longer periods, and at a much closer distance that can ever be reached here on the ground, or for that matter, by any spacecraft circling the Earth. 10 instruments will be flown that will study not only the corona but the Sun’s disk in great detail, the solar wind and the solar magnetic fields which will give us unprecedented insight into how our star works, and how we can better predict periods of stormy “space-weather” that the Sun throws our way from time to time.

The last of the ten instruments is being installed this month and the next step is system testing before the heatshield, antennas and boom are added towards the end of the year. In addition, the first instrument end-to-end electrical test has been performed successfully showing that the system works completely as expected.

By the time of the next global total eclipse, across the Pacific Ocean and South America on 2nd July 2019, Solar Orbiter will have begun its three and a half year journey to the inner solar system to get close to our Sun.


Quelle: Airbus


Update: 19.09.2018


Staring at the sun: Solar Orbiter telescopes will get closest view yet

European Space Agency’s seven-year, €1bn mission will investigate the effects of the sun on satellite technology


ESA’s next-generation Sun explorer, Solar Orbiter, will be launched in February 2020, and will take three and half years to complete its journey. Photograph: ESA

A new space mission will carry telescopes closer to the sun than ever before, capturing detailed images of its surface landscapes and taking measurements of its atmosphere.

Once it reaches its destination – the sun’s orbit – the spacecraft will be able to investigate the origins of the solar wind – the stream of ionised gas emanating from the sun – and of fierce explosions on its surface called solar flares, as well as taking pictures of the polar regions of the sun for the first time.

The European Space Agency’s Solar Orbiter will launch in February 2020 using a Nasa rocket from Cape Canaveral in Florida, and will take approximately three and a half years to reach its vantage point, about one fifth as far as Earth is from the sun. Before it gets there, it must first head for Venus and then manoeuvre back towards Earth, before finally dropping very close to the sun and adjusting its position until it eventually reaches a distance of about 42 million kilometres from its surface.

On 12 August, Nasa’s Parker solar probe started a similar perilous journey towards the sun, aiming to reach within 7 million kilometres of its surface, but it lacks the ability to gather images that the onboard telescopes give the Solar Orbiter.

“Most [previous] missions have been more focused on sampling the environment around the spacecraft or on looking at the surface of the sample. This is doing both in a way that hasn’t been done before,” said Michelle Sprake, a systems engineer at Airbus Defence and Space in the UK, who has been working on Solar Orbiter for the past eight years.

The seven-year mission, which is costing about €1bn, aims to do 20 flybys of the sun. To do this, Solar Orbiter will need to withstand a huge temperature range, from 600C when close to the sun to -180C in deep space. “It’s been one of the most challenging missions that we’ve ever developed,” said Justin Byrne, head of science at Airbus.

Solar Orbiter will help scientists understand and predict the effects of solar wind and big solar eruptions on communications and navigation systems on Earth.

“The overarching science question we are trying to answer is about how the sun creates this plasma bubble around it and about how solar activity changes through time and also changes this bubble we all live in,” said Daniel Müller, ESA’s Solar Orbiter project scientist.

Although on Earth we are continuously being “gently buffeted by the what is called the solar wind”, a big solar storm can affect spacecrafts, satellites and the accuracy of GPS signals, said Louise Harra, a professor of solar physics at UCL Mullard Space Science Laboratory and part of the Solar Orbiter project. “It wouldn’t affect you and I when using our satnavs,” she said, but it could affect someone using high precision GPS, for example, in oil drilling. Similarly, during a solar storm, aircraft are not allowed to rely on GPS signals and have to reroute.

Solar Orbiter is “one piece in the puzzle” in terms of trying to understand and predict these events with a bit more accuracy, so we can work out whether we’re going to be affected by them, said Sprake.

The mission scientists hope to understand what drives the sun’s magnetic field and its 11-year cycle of activity. Being able to study the poles will be central to this, said Harra. At the moment, “because we don’t know what’s at the poles, we’re missing a big part of the picture,” she said.

“We have never had the telescopes to look down and measure the magnetic field at the poles, to see what the structures are. It’s not just going to be black darkness, we believe. There are going to be some interesting phenomena there. And that global magnetic field is what drives the solar activity and the solar wind,” she told the Guardian.

The spacecraft is fitted with 21 sensors and 10 instruments which will look at the sun and at the surrounding environment, as well as a 3.1m by 2.4m protective heat shield made of multiple layers of insulation materials designed to reflect as much heat as possible.

“The spacecraft’s job is to deliver a precious cargo of 10 instruments to the vicinity of sun,” said Ian Walters, Solar Orbiter project manager at Airbus. The instruments are so sensitive that the spacecraft has to be completely clean, he said. The cleaning process has included baking each unit on the spacecraft and subjecting it to a purge using dry nitrogen.

Now that all the instruments have been installed and tested at the Airbus facilities in Stevenage, UK, engineers are busy wrapping up the spacecraft in thermal blankets before it can be shipped to IAGB facilities in Munich for final tests ahead of its launch.

The Solar Orbiter launch window is set for between 6 and 24 February 2020, said Walters. “That three week slot is fixed by the geometry of Earth and Venus. We will not miss it,” he added.

Quelle: The Guardian


Update: 17.10.2019


NASA Invites Media to Launch of Solar Orbiter Spacecraft


Scheduled to launch in February 2020, ESA’s (European Space Agency’s) Solar Orbiter spacecraft is shown in an illustration against the backdrop of an image of the Sun captured by NASA’s Solar Dynamics Observatory. Solar Orbiter will capture the very first images of the Sun’s polar regions. These images will provide key insights into the poorly-understood magnetic environment there, which helps drive the Sun’s 11-year cycle and its periodic outpouring of solar storms.
Credits: ESA/ATG MediaLab/NASA

NASA has opened media accreditation for the Feb. 5, 2020, launch of Solar Orbiter – a joint NASA/ESA (European Space Agency) mission that will address central questions concerning our star, the Sun.


Media prelaunch and launch activities will take place at NASA’s Kennedy Space Center in Florida and neighboring Cape Canaveral Air Force Station. To attend these activities, international media must apply for credentials by 4:30 p.m. EST Dec. 8. U.S. media must apply by 4:30 p.m. Jan. 12, 2020.


All media accreditation requests must be submitted online at:


For questions about accreditation, please email For other questions, contact Kennedy’s newsroom at 321-867-2468.


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.


As the main driver of space weather, it is essential to understand the behavior of the Sun to learn how to better safeguard our planet, space technology and astronauts. Solar Orbiter will study the Sun, its outer atmosphere and what drives the constant outflow of solar wind which affects Earth. The spacecraft will observe the Sun's atmosphere up close with high spatial resolution telescopes and compare these observations to measurements taken in the environment directly surrounding the spacecraft – together creating a one-of-a-kind picture of how the Sun can affect the space environment throughout the solar system.

Quelle: NASA


Update: 24.10.2019


British-built solar probe shipping to Florida launch site before Brexit deadline


The Solar Orbiter spacecraft is ready for shipment from a test center in Ottobrunn, Germany, to NASA’s Kennedy Space Center in Florida for final launch preparations. Credit: Airbus Defense and Space

The European Space Agency’s Solar Orbiter spacecraft — assembled in Britain and set for liftoff in February — has completed environmental testing in Germany and is scheduled to ride a cargo plane to NASA’s Kennedy Space Center in Florida to begin launch preparations Oct. 31, several weeks earlier than planned to avoid complications stemming from Brexit.

The robotic solar probe will be packaged inside a pristine shipping container for the trans-Atlantic flight from Germany to the Shuttle Landing Facility runway at Kennedy. Ground teams will then transport the spacecraft to the Astrotech processing facility in Titusville for final functional tests, fueling and encapsulation inside the payload shroud of a United Launch Alliance Atlas 5 rocket.

The mission is jointly managed and funded by ESA, individual European member states, and NASA, with the U.S. space agency responsible for providing a launch for Solar Orbiter.

Liftoff of the Atlas 5 with Solar Orbiter from Cape Canaveral’s Complex 41 launch pad is scheduled during a two-hour window opening at 11:27 p.m. EST (0427 GMT on Feb. 6), according to Tim Dunn, the NASA launch director for the mission.

Airbus Defense and Space built the Solar Orbiter spacecraft at the company’s facility in Stevenage, England, north of London. The spacecraft departed the Airbus factory last year to begin a year-long test series at IABG in Ottobrunn, Germany, near Munich.

Solar Orbiter recently finished testing in Germany, and engineers confirmed the spacecraft can withstand the vibrations of launch and the extreme environmental conditions of space.

Günther Hasinger, the director of science programs at ESA, said mission managers decided to ship the spacecraft from its test site in Germany to the United States before the United Kingdom’s current date to leave the European Union on Oct. 31.

“There was a worry at some point, if a hard Brexit were to happen on the 31st of October, this could actually cause some severe disturbances in terms of customs,” Hasinger said. “It was a kind of risk mitigation assessment. We said let’s ship as early as possible just to avoid any turbulence.”

Although the spacecraft is currently in Germany, much of the hardware on Solar Orbiter originated in Britain, which raises export concerns related to Brexit, officials said. The date for Brexit, and whether Britain will leave the EU with or without a withdrawal agreement, remained unclear as of Tuesday.

The United Kingdom will remain a member state of ESA.

After launch, Solar Orbiter, or SolO, will use use gravitational assist flybys with Earth and Venus, placing the spacecraft in an orbit inside that of Mercury in 2022. Working in tandem with NASA’s Parker Solar Probe, Solar Orbiter will provide scientists will detailed measurements of the solar wind, and search for the drivers behind massive eruptions like solar flares.

“Solar Orbiter is clearly a new class in its own,” Hasinger said. “It has loads of instruments, which will go not as close as Parker Solar Probe, but quite close. Solar Orbiter will also have eyes. Parker Solar Probe can only sense and measure the plasma and the magnetic field, but Solar Orbiter also has six instruments that can really look at the sun, which is quite a challenge when you think it is reaching an environment where it’s about 600 degrees Celsius (1,100 degrees Fahrenheit). It’s like being in a pizza oven, so you have to make sure that you don’t burn the instruments.”

Parker Solar Probe , launched last year, faces much hotter conditions, where scorching temperatures would melt any camera exposed to the sun.

The planetary flybys will also use gravity to nudge Solar Orbiter into an inclined orbit around the sun, outside of the plane of the planets.

“One additional interesting element that has never been done before is that Solar Orbiter will be able to image the poles of the sun,” Hasinger said. “There are still mysteries around our understanding of the energy sources in the sun that produces the magnetic field and solar flares. A lot of people now think that some of the mysteries are actually hidden in the poles, which we have never seen.”

Scientists say the polar regions may also play a role in regulating the sun’s 11-year cycle.

ESA funded more than half of Solar Orbiter’s budget, and development of the mission took a few years longer than anticipated. When ESA approved the mission in 2012, Solar Orbiter was planned for launch in 2017.

The rest of the funding came from NASA and European member states, which paid for Solar Orbiter’s launch and scientific instruments.

“If you add up everything, it ends up in the 1.4 to 1.5 billion euro ($1.5 billion to $1.7 billion) range,” Hasinger said.

Before Solar Orbiter’s launch in February, ULA plans another Atlas 5 launch set for Dec. 17 carrying Boeing’s Starliner crew capsule into Earth orbit on its first unpiloted test flight to the International Space Station. The Orbital Flight Test mission, under contract to NASA, is a prerequisite for astronaut flights on the Starliner spacecraft next year.

After another round of delays, NASA Administrator Jim Bridenstine said this month that the commercial crew program is the agency’s highest priority. Until new crew capsules from Boeing and SpaceX begin flying, NASA must rely on Russian Soyuz spacecraft to ferry astronauts to and from the space station.

In an interview last week, Dunn said launching the Starliner capsule Dec. 17 and then Solar Orbiter on Feb. 5 would be a “pretty quick turnaround” for the Atlas 5 team.

But it’s doable, he said.

“ULA continues sharpening their pencils and the dates are kind of fluid right now, but they believe that they have about a week-and-half, or just under two weeks, of opportunities for Starliner and the OFT mission beginning on the 17th (of December),” Dunn said. “So they were talking, kind of in rough terms, probably 11 opportunities, maybe the 17th through the 27th before things would then begin to put some pressure on the Solar Orbiter mission.”

Stacking of the Atlas 5 rocket for Solar Orbiter is currently scheduled to begin Jan. 3, Dunn said.

Solar Orbiter has 19 daily launch opportunities through Feb. 23. If the mission is not launched in February, Solar Orbiter’s next opportunity to leave Earth is in October 2020, when the Earth and Venus are again in the correct position in the solar system to enable the spacecraft’s series of planetary flybys.

If the Starliner test flight is delayed more than a couple of weeks, NASA leaders will have to decide whether to prioritize the commercial crew demonstration mission or Solar Orbiter in ULA’s launch manifest. Dunn said teams at Kennedy are providing updates on the Starliner and Solar Orbiter launch opportunities to NASA Headquarters, just in case senior agency managers prioritize one launch over the other.

In addition to the high priority assigned to NASA’s commercial crew program, Solar Orbiter’s limited planetary launch opportunities, the spacecraft’s previous delays, and the international nature of the mission could also factor in to the agency’s decision.

Quelle: SN


Update: 3.11.2019


Solar Orbiter arrives at Kennedy Space Center for launch preps


The Solar Orbiter spacecraft arrived at the Kennedy Space Center’s Shuttle Landing Facility shortly after 9 p.m. EDT Friday (0100 GMT Saturday) after a trans-Atlantic journey from Germany aboard an Antonov An-124 transport plane. Credit: ESA/J. Fiebrich

The European-built Solar Orbiter spacecraft arrived in Florida late Friday after a trans-Atlantic journey from a test center in Germany, ready to begin preparations for a liftoff from Cape Canaveral in February aboard a United Launch Alliance Atlas 5 rocket.

Packed inside a climate-controlled shipping container, the Solar Orbiter spacecraft rode an Antonov An-124 transport plane from Munich to the Shuttle Landing Facility at NASA’s Kennedy Space Center in Florida, where the aircraft touched down shortly after 9 p.m. EDT Friday (0100 GMT Saturday).

The spacecraft, built by Airbus Defense and Space, was expected to be transported by road to the Astrotech satellite processing facility in nearby Titusville, where ground teams will spend the next two-and-a-half months testing, fueling and readying Solar Orbiter for liftoff.

Ten scientific instruments aboard Solar Orbiter will measure the sun’s output and take the first detailed images of the sun’s poles. NASA is paying for the launch of the European Space Agency science probe as part of an international collaboration on the nearly $1.7 billion Solar Orbiter mission.

Scientists will use data from Solar Orbiter, in tandem with measurements from NASA’s Parker Solar Probe, to better understand what causes the solar wind, and what drives the 11-year solar cycle.

“Solar Orbiter is clearly a new class in its own,” Hasinger said. “It has loads of instruments, which will go not as close as Parker Solar Probe, but quite close. Solar Orbiter will also have eyes. Parker Solar Probe can only sense and measure the plasma and the magnetic field, but Solar Orbiter also has six instruments that can really look at the sun, which is quite a challenge when you think it is reaching an environment where it’s about 600 degrees Celsius (1,100 degrees Fahrenheit). It’s like being in a pizza oven, so you have to make sure that you don’t burn the instruments.”

Parker Solar Probe, launched last year, faces much hotter conditions, where scorching temperatures would melt any camera exposed to the sun.

After launch, Solar Orbiter, or SolO, will use use gravitational assist flybys with Earth and Venus, placing the spacecraft in an orbit inside that of Mercury in 2022. Solar Orbiter’s final orbit will bring the spacecraft within 26 million miles (42 million kilometers) from the sun.

Artist’s concept of the Solar Orbiter spacecraft. Credit: ESA

The planetary flybys will also use gravity to nudge Solar Orbiter into an inclined orbit around the sun, outside of the plane of the planets.

“One additional interesting element that has never been done before is that Solar Orbiter will be able to image the poles of the sun,” Hasinger said. “There are still mysteries around our understanding of the energy sources in the sun that produces the magnetic field and solar flares. A lot of people now think that some of the mysteries are actually hidden in the poles, which we have never seen.”

“Solar Orbiter is a science mission that will go close to the sun to take crucial measurements and try to find out how the heliosphere of the sun is operating, is working,” said César García, Solar Orbiter’s project manager at ESA. “To do that, it carries a series of instruments, actually 10 instruments. Some of them will be taking in situ measurements. They will be taking particles as they come off the sun.

“At the same time, they will be taking remote images and spectrographs of the sun’s surface, of the sun’s corona, and of the sun’s heliosphere to try and correlate what happens in those areas of the sun with the particles which are circulated,” García said.

United Launch Alliance plans to transport components of Solar Orbiter’s Atlas 5 rocket to Cape Canaveral later this month from the company’s factory in Decatur, Alabama.

Solar Orbiter will launch on a rarely-used configuration of the Atlas 5 known as the “411” version, with a single strap-on solid rocket booster on one side of the Atlas 5’s kerosene-fueled core stage.

Stacking of the Atlas 5 rocket for Solar Orbiter will begin Jan. 3 inside the Vertical Integration Facility at Cape Canaveral’s Complex 41 launch pad. A wet dress rehearsal, or fueling test, is planned Jan. 21 at pad 41.

Then Solar Orbiter will be added to the the top of the Atlas 5 rocket for a liftoff scheduled for 11:27 p.m. EST on Feb. 5 (0427 GMT on Feb. 6), the first of 19 daily launch opportunities in February.

If the launch does not occur in February, the mission’s next launch period opens in October 2020, when Earth and Venus are again in the proper position in the solar system to make Solar Orbiter’s interplanetary trajectory possible.

There is some concern among ESA and NASA teams that Solar Orbiter’s launch could be impacted by any further delays to a planned Dec. 17 Atlas 5 launch of Boeing’s Starliner commercial crew capsule on an unpiloted test flight to the International Space Station.

Both missions will use the same launch pad at Cape Canaveral.

The human-rated spaceship is one of two new commercial crew capsules NASA is funding — along with SpaceX’s Crew Dragon — to end U.S. reliance on Russian Soyuz ferry ships to carry astronauts to the International Space Station. Both new vehicles have faced delays, and NASA is eager to begin flying astronauts on U.S. spaceships for the first time since the retirement of the space shuttle in 2011.

Tim Dunn, NASA’s launch director for the Solar Orbiter mission, said last month the Solar Orbiter launch campaign could be impacted if the Starliner launch is delayed beyond around Dec. 27. The Starliner test flight is a major demonstration before the Boeing crew capsule is cleared to carry astronauts into orbit next year.

NASA has a role in both the Starliner and Solar Orbiter missions, and delays in the Boeing crew capsule test flight may force agency leaders to decide which mission will ultimately receive top priority in ULA’s launch manifest.

In addition to the high priority assigned to NASA’s commercial crew program, Solar Orbiter’s limited planetary launch opportunities, the spacecraft’s previous delays, and the international nature of the mission could also factor in to the agency’s decision.

Quelle: SN