February 10

10 February 1974

Mars 4 and Mars 5 spacecraft. Credit: NPO Lavochkin

On February 10, 1974, Mars 4 spacecraft failed to enter orbit around Mars and instead flew past the planet, with the closest approach being 1844 km. During its flyby the probe returned 12 photographs and two panoramas of the surface from its cameras.

   Mars 4 was intended to be a Mars orbiter mission. Less than four months prior to launch, ground testing detected a major problem with the 2T312 transistors, which used aluminum instead of gold-plated contacts, dramatically increasing degradation. The spacecraft was launched by a Proton-K with Block D launch vehicle on July 21, 1973. A mid-course correction burn was made on July 30, 1973, but soon two of three channels of the onboard computer failed due to the faulty transistors. As a result, the second mid-course correction by its main engine could not be implemented.

   With no possibility for Mars orbit insertion, Mars 4 flew by the Red Planet at 15:34 UT on 10 February 1974 at a range of 1,844 kilometers. Ground control was able to command the vehicle to turn on its TV imaging system (Vega-3MSA) 2 minutes prior to this point (at 15:32:41) to begin a short photography session of the Martian surface during the flyby. (The other TV camera system known as Zufar-2SA was never turned on due to a failure). The TV camera took 12 standard images from ranges of 1,900 to 2,100 kilometers distance over a period of 6 minutes. The other OMS scanner also provided two panoramas of the surface. The spacecraft also returned some radio occultation data which constituted the first detection of the nightside ionosphere on Mars, and eventually entered heliocentric orbit.

Image taken by Mars 4 during its flyby. Credit: Don P. Mitchell: http://mentallandscape.com/

Another image taken by Mars 4. Credit: Don P. Mitchell: http://mentallandscape.com/

See also: Mars 5, Mars 6, Mars 7 

© 2026, Andrew Mirecki

10 February 1990

Venus as seen by the Galileo spacecraft as it swung by the planet for a gravitational boost on its way to Jupiter in 1990. The image has been processed to increase contrast and remove minor artifacts. The color is added. Credit: NASA / JPL / Bill Dunford

The Galileo spacecraft passed Venus on its way to Jupiter on February 10, 1990, less than 4 months after launch from Earth aboard the shuttle Atlantis. The flyby, at a range of 16,123 kilometers at 5:59 UTC, added 2.2 kilometers per second to the spacecraft’s heliocentric velocity changing Galileo’s solar orbit from 0.67 by 1.00 au to a larger 0.70 by 1.29 au orbit. 

   The Venus flyby geometry was designed to swing the spacecraft back to Earth on December 8, 1990, for a flyby angled to put Galileo in a two-year elliptical orbit around the Sun, bringing it back again on December 8, 1992. This third planetary swingby boosted the spacecraft into an ellipse long enough to reach Jupiter in December 1995.

   Because Galileo's instruments were selected for broad-based planetary exploration, the spacecraft was able to obtain a wide range of measurements during the Venus encounter. Instrumentation used included UV spectra, limb opacity studies, and particle and field experiments. Together with ground-based observations conducted during the encounter, these observations have yielded more accurate information about the planet's plasma environment, cloud patterns, and the possible existence of lightning.

   Since Galileo’s umbrella-like high gain antenna was not designed to withstand the thermal environment this close to the Sun, it remained furled behind a sunshade during this stage of the mission. This forced Galileo to delay the transmission of its Venus observations, stored on the spacecraft tape recorder, until it was closer to Earth when the data could be transmitted home using a low gain antenna – a task which was completed by mid-November 1990.

Image of Venus taken in violet-light by Galileo's Solid State Imaging System, about 6 days after the closest approach. Credit: NASA/JPL

A near-infrared map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet's night side on February 10, 1990. Bright slivers of sunlit high clouds are visible above and below the dark, glowing hemisphere. The spacecraft is about 100,000 kilometers above the planet. An infrared wavelength of 2.3 microns was used. The map shows the turbulent, cloudy middle atmosphere some 50-55 km above the surface, 10-16 km below the visible cloudtops. The red color represents the radiant heat from the lower atmosphere shining through the sulfuric acid clouds. Credit: NASA/JPL

© 2026, Andrew Mirecki

10 February 2020

Artist's impression of the Solar Orbiter. Credit: ESA

On February 10, 2020, Solar Orbiter, an international cooperative mission between ESA (European Space Agency) and NASA, was launched aboard an Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station in Florida. The mission aims to study the Sun, its outer atmosphere and solar wind. A series of Venus and Earth gravity assists will adjust the probe’s perihelion to a minimum of 0.28 au (42 million km) and raise the inclination of the orbital plane to over 33 degrees. This will allow the first-ever look at the solar poles.

   Gravity assist manoeuvres at Earth and Venus enable Solar Orbiter to change inclination to observe the Sun from different perspectives. During the initial cruise phase, from launch 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, and tested and calibrated its remote-sensing instruments. 

   The spacecraft’s orbit has been chosen to be ‘in resonance’ with Venus, which means that it returns to the planet’s vicinity every few orbits and can repeatedly use the planet’s gravity to alter or tilt its orbit. Initially Solar Orbiter was flying in the same plane as the planets, but each encounter of Venus increases its orbital inclination. After the 2025 Venus encounter it made its first solar observations at 17° inclination (measured from the Sun's equator), increasing to 33° during a proposed mission extension phase. Solar Orbiter is the first spacecraft to take images of the Sun's polar regions, offering humankind's first clear views of these unexplored regions.

The Solar Orbiter spacecraft is prepared for encapsulation in the Atlas V payload fairing on January 20, 2020. Credit: NASA/Ben Smegelsky

Full Description from NASA Space Science Data Coordinated Archive:

   The European Space Agency (ESA) Solar Orbiter mission will study the Sun from a highly elliptical orbit getting as close as 0.28 au (42 million km), from which it will use a suite of instruments to make high-latitude observations of the Sun and heliosphere, including the magnetic field, energetic particles, solar wind, and transient phenomena. Solar Orbiter has as its primary science objectives: to study the drivers of the solar wind and the origin of the coronal magnetic field; to determine how solar transients drive heliospheric variability; to learn how solar eruptions produce the energetic particles that fill the heliosphere; and to study how the solar dynamo works and drives connections between the Sun and the heliosphere.

   Solar Orbiter comprises a 2.5 x 3.0 x 2.5 meter box-shaped bus with two solar panel wings spanning 18 meters to supply power. Total launch mass is 1800 kg. There is a 4.4 meter instrument boom and three 6.5 meter antennas protruding from the spacecraft body. A carbon fiber composite, titanium layered solar shield covers one side of the spacecraft. The shield has apertures for various instruments. The spacecraft is 3-axis stabilized to keep the heat shield oriented towards the Sun. Telemetry is dual X-band through steerable medium and high-gain antennas. Low gain antennas are used in the launch and early orbit phase, and are available for backup.

Atlas V 411 launch vehicle, carrying the Solar Orbiter, lifts off Space Launch Complex 41 at Cape Canaveral Air Force Station. Credit: NASA

   Solar Orbiter carries two types of instruments, in-situ instruments making direct measurements of the heliospheric environment, and remote sensing instruments, which view the Sun and heliosphere from a distance. The in-situ instruments comprise an Energetic Particle Detector (EPD), a Magnetometer (MAG), a Radio and Plasma Waves sensor (RPW), and a Solar Wind Plasma Analyser (SWA). The remote-sensing instruments are an Extreme Ultraviolet Imager (EUI), a Coronagraph (METIS), a Polarimetric and Helioseismic Imager (PHI), a Heliospheric Imager (SoloHI), a Spectral Imaging of the Coronal Environment (SPICE), and an X-ray Spectrometer/Telescope (STIX). Total scientific payload mass is 209 kg.

   Solar Orbiter launched from Cape Canaveral Air Force Station, SLC‑41, on February 10, 2020 at 04:03 UT. The spacecraft launched on an Atlas V 411 (AV-087) into a short Earth parking orbit followed by injection into an elliptical heliocentric orbit. The first perihelion was in June 2020. The mission will use six gravity assist maneuvers: one Earth flyby (27 Nov 2021) and five Venus flybys (27 Dec 2020, 9 Aug 2021, 4 Sep 2022, 18 Feb 2025, and 24 Dec 2026) during the 7-year nominal mission. This will bring the orbit to an inclination of 25 degrees with a perihelion of 0.28 au, an aphelion of 0.91 au, and a period of 168 days. It will make 14 perihelion passes during the nominal mission. If a three year extended mission is approved, Solar Orbiter will make three more Venus flybys (18 Mar 2028, 10 Jun 2029, 3 Sep 2030) to bring the inclination to 33 degrees. The extended mission will involve 8 more perihelion passes.

Artist impression of Solar Orbiter during its second flyby of the planet. Credit: ESA/ATG medialab

The Sun as seen by Solar Orbiter in extreme ultraviolet light from a distance of roughly 75 million kilometres. The image is a mosaic of 25 individual images taken on 7 March 2022 by the high resolution telescope of the Extreme Ultraviolet Imager (EUI) instrument. Taken at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum, this image reveals the Sun’s upper atmosphere, the corona, which has a temperature of around a million degrees Celsius. Credit: ESA & NASA/Solar Orbiter/EUI team

Solar Orbiter's view of the Sun's south pole on 23 March 2025. It was taken by the spacecraft's Extreme Ultraviolet Imager (EUI) instrument, which captures the ultraviolet light sent out by the million-degree gas in the Sun's outer atmosphere (the corona). Credit: ESA & NASA/Solar Orbiter/EUI Team, D. Berghmans

© 2026, Andrew Mirecki

10 February 2021

Tianwen 1 in Mars orbit seen from the subsatellite. Credit: CNSA

On February 10, 2021, Chinese Tianwen 1 spacecraft entered orbit around Mars. On board was the lander with the Zhurong rover, that landed on the planet on May 14, 2021.

   Tianwen 1 launched from Wenchang launch complex on a Long March 5 Y-4 booster on July 23, 2020 at 04:41 UT. The mission made a 7 month trip to Mars, arriving and going into orbit on February 10, 2021. Orbit was achieved at about 12:18 UT Earth Received Time (Time delay was 10 min., 40 sec.) after a 14-15 minute braking thruster firing. The initial orbit had an inclination of 10 degrees and an altitude of 400 x 180,000 km with a period of 10 days. The orbiter used high-resolution cameras to search for the nominal landing site for the lander and rover. They separated from the orbiter and made a landing in the Utopia Planitia region at 23:18 UT on May 14, 2021. The orbiter then went into a 265 x 12,000 km altitude polar orbit, from which it made scientific measurements and acted as a relay for the rover communications with Earth.

Picture taken by Tianwen-1 spacecraft during Mars orbit insertion on February 10, 2021. Credit: CNSA/Thomas Appéré

Northern pole of Mars seen from Tianwen 1. Credit: CNSA

Image of the cloudy Arsia Mons taken by Tianwen 1 on February 2, 2022. Credit: CNSA/CLEP/PEC/MoRIC/Andrea Luck

© 2026, Andrew Mirecki