Solar Orbiter

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Solar Orbiter
Solar Orbiter orbiting the Sun.png
Artist's impression of the Solar Orbiter orbiting the Sun
Mission typeSolar heliophysics orbiter
Operator ESA / NASA
COSPAR ID 2020-010A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 45167
Website www.esa.int
Mission duration7 years (nominal)
+ 3 years (extended) [1] [2]
Elapsed: 4 years, 2 months and 5 days
Spacecraft properties
Manufacturer Airbus Defence and Space
Launch mass1,800 kg (4,000 lb) [3]
Payload mass209 kg (461 lb) [4]
Dimensions2.5 × 3.1 × 2.7 m (8 × 10 × 9 ft) [3]
Power180 watts [3]
Start of mission
Launch date10 February 2020, 04:03 UTC [5]
Rocket Atlas V 411 (AV-087) [6]
Launch site Cape Canaveral, SLC-41
Contractor United Launch Alliance
Entered serviceNovember 2021
(start of main mission)
Orbital parameters
Reference system Heliocentric
Regime Elliptic orbit
Perihelion altitude 0.28 au [6]
Aphelion altitude 0.91 au
Inclination 24° (nominal mission)
33° (extended mission)
Period 168 days
Epoch ?
Main
Type Ritchey–Chrétien reflector
Diameter160 mm
Focal length2.5 m
Wavelengths Visible light, ultraviolet, X-rays
Solar orbiter insignia.png
Insignia for the Solar Orbiter mission.
  CHEOPS
Euclid  
 

The Solar Orbiter (SolO) [7] is a Sun-observing probe developed by the European Space Agency (ESA) with a National Aeronautics and Space Administration (NASA) contribution. Solar Orbiter, designed to obtain detailed measurements of the inner heliosphere and the nascent solar wind, will also perform close observations of the polar regions of the Sun which is difficult to do from Earth. These observations are important in investigating how the Sun creates and controls its heliosphere.

Contents

SolO makes observations of the Sun from an eccentric orbit moving as close as ≈60 solar radii (RS), or 0.284 astronomical units (au), placing it inside Mercury's perihelion of 0.3075 au. [8] During the mission the orbital inclination will be raised to about 24°. The total mission cost is US$1.5 billion, counting both ESA and NASA contributions. [9]

SolO was launched on 10 February 2020 from Cape Canaveral, Florida (USA). The nominal mission is planned until the end of 2026, with a potential extension until 2030.

A comparison of the size of the Sun as seen from Earth (left, 1 au) and from the Solar Orbiter spacecraft (0.284 au, right) Suncomparison.svg
A comparison of the size of the Sun as seen from Earth (left, 1 au) and from the Solar Orbiter spacecraft (0.284 au, right)
The Solar Orbiter structural thermal model shortly before leaving the Airbus Defence and Space facility in Stevenage, UK Solar Orbiter Structural Thermal Model.jpg
The Solar Orbiter structural thermal model shortly before leaving the Airbus Defence and Space facility in Stevenage, UK

Spacecraft

The Solar Orbiter spacecraft is a Sun-pointed, three-axis stabilised platform with a dedicated heat shield to provide protection from the high levels of solar flux near perihelion. The spacecraft provides a stable platform to accommodate the combination of remote-sensing and in situ instrumentation in an electromagnetically clean environment. The 21 sensors were configured on the spacecraft to allow each to conduct its in situ or remote-sensing experiments with both access to and protection from the solar environment. Solar Orbiter has inherited technology from previous missions, such as the solar arrays from the BepiColombo Mercury Planetary Orbiter (MPO). The solar arrays can be rotated about their longitudinal axis to avoid overheating when close to the Sun. A battery pack provides supplementary power at other points in the mission such as eclipse periods encountered during planetary flybys.

The Telemetry, Tracking and Command Subsystem provides the communication link capability with the Earth in X-band. The subsystem supports telemetry, telecommand and ranging. Low-Gain Antennas are used for Launch and Early Orbit Phase (LEOP) and now function as a back-up during the mission phase when steerable Medium- and High-Gain Antennas are in use. The High-Temperature High-Gain Antenna needs to point to a wide range of positions to achieve a link with the ground station and to be able to downlink sufficient volumes of data. Its design was adapted from the BepiColombo mission. The antenna can be folded in to gain protection from Solar Orbiter's heat shield if necessary. Most data will therefore initially be stored in on-board memory and sent back to Earth at the earliest possible opportunity.

The ground station at Malargüe (Argentina), with a 35-metre (115 ft) antenna, is used for 4 to 8 hours/day (effective). ESA's Malargüe ground station will be used for all operations throughout the mission with the ground stations in New Norcia, Australia, and Cebreros, Spain, acting as backup when necessary. [1]

Mission operations

Animation of Solar Orbiter's trajectory
Animation of Solar Orbiter's trajectory - polar view.gif
Polar view. For more detailed animation, see this video
Animation of Solar Orbiter's trajectory - equatorial view.gif
Equatorial view
   Solar Orbiter  ·  Mercury ·  Venus ·  Earth ·  Sun

During nominal science operations, science data is downlinked for eight hours during each communication period with the ground station. Additional eight-hour downlink passes are scheduled as needed to reach the required total science data return of the mission. The Solar Orbiter ground segment makes maximum reuse of ESA's infrastructure for Deep Space missions:

The Science Operations Centre was responsible for mission planning and the generation of payload operations requests to the MOC, as well as science data archiving. The SOC has been operational for the active science phase of the mission, i.e. from the beginning of the Cruise Phase onwards. The handover of payload operations from the MOC to the SOC is performed at the end of the Near-Earth Commissioning Phase (NECP). ESA's Malargüe Station in Argentina will be used for all operations throughout the mission, with the ground stations of New Norcia Station, Australia, and Cebreros Station, Spain, acting as backup when necessary. [10]

During the initial cruise phase, which lasted until November 2021, Solar Orbiter performed two gravity-assist manoeuvres around Venus and one around Earth to alter the spacecraft's trajectory, guiding it towards the innermost regions of the Solar System. At the same time, Solar Orbiter acquired in situ data to characterise and calibrate its remote-sensing instruments. The first close solar pass took place on 26 March 2022 at around a third of Earth's distance from the Sun. [11] [12]

The spacecraft's orbit has been chosen to be 'in resonance' with Venus, which means that it will return to the planet's vicinity every few orbits and can again use the planet's gravity to alter or tilt its orbit. Initially, Solar Orbiter will be confined to the same plane as the planets, but each encounter of Venus will increase its orbital inclination. For example, after the 2025 Venus encounter, it will make its first solar pass at 17° inclination, increasing to 33° during a proposed mission extension phase, bringing even more of the polar regions into direct view. [11]

Scientific objectives

The spacecraft makes a close approach to the Sun every six months. [3] The closest approach will be positioned to allow a repeated study of the same region of the solar atmosphere. Solar Orbiter will be able to observe the magnetic activity building up in the atmosphere that can lead to powerful solar flares or eruptions.

Researchers also have the chance to coordinate observations with NASA's Parker Solar Probe mission (2018–2025) which is performing measurements of the Sun's extended corona, as well as other ground-based assets such as the Daniel K. Inouye Solar Telescope.

The objective of the mission is to perform close-up, high-resolution studies of the Sun and its inner heliosphere. The new understanding will help answer these questions:

Science results

Since the launch of the mission, a series of papers have been released in three special issues of the Astronomy and Astrophysics Journal:

Meanwhile, regular "science nuggets" are released on the Solar Orbiter science community website.

Instruments

The science payload is composed of 10 instruments: [13]

Heliospheric in-situ instruments (4)
Solar remote-sensing instruments (6)

Institutions involved

Solar Orbiter spacecraft is prepared for encapsulation in the United Launch Alliance Atlas V payload fairing. Solar Orbiter spacecraft is prepared for encapsulation in the United Launch Alliance Atlas V payload fairing.jpg
Solar Orbiter spacecraft is prepared for encapsulation in the United Launch Alliance Atlas V payload fairing.

The following institutions operate each instrument: [19]

Launch and flight

Launch delays

The launch of Solar Orbiter from Cape Canaveral at 11.03pm EST on 9 February 2020 (US date) Solar Orbiter launch closeup.jpg
The launch of Solar Orbiter from Cape Canaveral at 11.03pm EST on 9 February 2020 (US date)

In April 2015, the launch was set back from July 2017 to October 2018. [21] In August 2017, Solar Orbiter was considered "on track" for a launch in February 2019. [22] The launch occurred on 10 February 2020 [5] on an Atlas V 411. [23]

Launch

The Atlas V 411 (AV-087) lifted off from SLC-41 at Cape Canaveral, Florida, at 04:03 UTC. The Solar Orbiter spacecraft separated from the Centaur upper stage nearly 53 minutes later, and the European Space Agency acquired the first signals from the spacecraft a few minutes later. [9]

Trajectory

After launch, Solar Orbiter will take approximately 3.5 years, using repeated gravity assists from Earth and Venus, to reach its operational orbit, an elliptical orbit with perihelion 0.28 AU and aphelion 0.91 AU. The first flyby was of Venus in December 2020. Over the expected mission duration of 7 years, it will use additional gravity assists from Venus to raise its inclination from 0° to 24°, allowing it a better view of the Sun's poles. If an extended mission is approved, the inclination could rise further to 33°. [1] [24]

During its cruise phase to Venus, Solar Orbiter passed through the ion tail of Comet C/2019 Y4 (ATLAS) from 31 May to 1 June 2020. It passed through the comet's dust tail on 6 June 2020. [25] [26]

In June 2020, Solar Orbiter came within 77,000,000 km (48,000,000 mi) of the Sun, and captured the closest pictures of the Sun ever taken. [27]

Mission timeline

The speed of the probe and distance from the Sun Timeline of Solar orbiter.svg
The speed of the probe and distance from the Sun

Solar Orbiter and Parker Solar Probe collaboration

In 2022, SolO and NASA's Parker Solar Probe (PSP) collaborated to study why the Sun's atmosphere is "150 times hotter" than its surface. SolO observed the Sun from 140 million kilometers, with PSP simultaneously observed the Sun's corona during flyby at a distance of nearly 9 million kilometers. [36] [37]

In March 2024, both space probes are at their closest approach to the Sun, PSP at 7.3 million km, and SolO at 45 million km. SolO observed the Sun, while PSP sampled the plasma of solar wind, that allowed scientists to compare data from both probes. [38]

Outreach

Solar Orbiter news are regularly updated and listed in the official ESA public pages , as well as on the Twitter/X account .

Images taken by the spacecraft with various instruments can be found on the official Flickr account.

See also

Related Research Articles

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A corona is the outermost layer of a star's atmosphere. It is a hot but relatively dim region of plasma populated by intermittent coronal structures known as solar prominences or filaments.

<span class="mw-page-title-main">Solar wind</span> Stream of charged particles from the Sun

The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5 and 10 keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei of elements such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, and 58Ni, 60Ni, and 62Ni. Superimposed with the solar-wind plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and over solar latitude and longitude. Its particles can escape the Sun's gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. The boundary separating the corona from the solar wind is called the Alfvén surface.

<i>Ulysses</i> (spacecraft) 1990 robotic space probe; studied the Sun from a near-polar orbit

Ulysses was a robotic space probe whose primary mission was to orbit the Sun and study it at all latitudes. It was launched in 1990 and made three "fast latitude scans" of the Sun in 1994/1995, 2000/2001, and 2007/2008. In addition, the probe studied several comets. Ulysses was a joint venture of the European Space Agency (ESA) and the United States' National Aeronautics and Space Administration (NASA), under leadership of ESA with participation from Canada's National Research Council. The last day for mission operations on Ulysses was 30 June 2009.

<span class="mw-page-title-main">Solar and Heliospheric Observatory</span> European space observatory

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<span class="mw-page-title-main">Heliosphere</span> Region of space dominated by the Sun

The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstellar medium. The "bubble" of the heliosphere is continuously "inflated" by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating the Milky Way. As part of the interplanetary magnetic field, the heliosphere shields the Solar System from significant amounts of cosmic ionizing radiation; uncharged gamma rays are, however, not affected. Its name was likely coined by Alexander J. Dessler, who is credited with the first use of the word in the scientific literature in 1967. The scientific study of the heliosphere is heliophysics, which includes space weather and space climate.

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<span class="mw-page-title-main">STEREO</span> Solar observation mission (2006–present)

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<span class="mw-page-title-main">Solar Dynamics Observatory</span> NASA mission, launched in 2010 to SE-L1

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<span class="mw-page-title-main">Parker Solar Probe</span> NASA robotic space probe of the outer corona of the Sun

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<span class="mw-page-title-main">Energetic neutral atom</span> Technology to create global images of otherwise invisible phenomena

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<span class="mw-page-title-main">Heliophysics Science Division</span>

The Heliophysics Science Division of the Goddard Space Flight Center (NASA) conducts research on the Sun, its extended Solar System environment, and interactions of Earth, other planets, small bodies, and interstellar gas with the heliosphere. Division research also encompasses geospace—Earth's uppermost atmosphere, the ionosphere, and the magnetosphere—and the changing environmental conditions throughout the coupled heliosphere.

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<span class="mw-page-title-main">Eckart Marsch</span> German theoretical physicist

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<span class="mw-page-title-main">Magnetic switchback</span>

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