February 12

12 February 1947

Painting of the Sikhote-Alin meteorite fall by by Pyotr Medvedev, a Soviet artist who witnessed the fall

On February 12, 1947, at around 10:30 local time, a large iron meteoroid exploded and fell over the Sikhote-Alin mountains in Primorsky Krai, Russia, creating one of the largest meteorite falls observed in recorded history. The meteoroid is estimated to have a pre-atmospheric mass of around 200–500 tons and a post-atmospheric mass of around 100 tons. As it traveled at ~12–15 km/s, the meteorite left a trail of smoke in its wake approximately 32 kilometers long that remained in the sky for hours after impact. Fragmentation probably occurred in two stages, with breakups at altitudes of ~22–28 km and at ~16 km and lower.

The meteorite shattered in a powerful airburst explosion, causing a rain of debris. The bright flash and the loud sound of the fall were observed for 300 kilometres around the point of impact not far from Luchegorsk and approximately 440 km northeast of Vladivostok. Fragments from this explosion were driven into trees and in one case created an impact crater 26 metres across and 6 metres deep. The dispersion ellipse was about 12 × 4 km. To date, more than 9,000 iron meteorites weighing a total of some 28 to 29 tons have been collected. The largest weighs 1,745 kg, the smallest less than a gram.

Fragment the Sikhote-Alin meteorite. Unknown author

The Sikhote Alin meteorite is classified as an iron meteorite in the IIAB group with a coarse octahedrite structure. This group has the lowest concentration of nickel in iron meteorites and is formed from the metallic core of a celestial body. It is composed of approximately 93% iron, 5.9% nickel, 0.42% cobalt, 0.46% phosphorus and 0.28% sulfur, with trace amounts of germanium and iridium. Minerals present include taenite, plessite, troilite, chromite, kamacite and schreibersite. The age of this group has been estimated using a radiometric dating process involving rhenium-osmium isotopes, putting their formation at over 4 billion years ago.

Fragment the Sikhote-Alin meteorite. Credit: Wikimedia Commons

Section of the meteorite. Credit: André Knöfel/Wikimedia Commons

12 February 1961

Model of Venera 1 in a museum

Automatic Interplanetary Station (retroactively named Venera 1), the first spacecraft to fly past Venus, was launched on February 12, 1961, from the Baikonur Cosmodrome by a four-stage 8K78 launch vehicle. It was the second of two Soviet attempts to launch a probe to Venus in February 1961, immediately following the launch of its sister ship Venera-1VA No.1, which failed to leave Earth orbit due to the failure of a power transformer. This time, the probe successfully exited Earth orbit and headed towards Venus.

The probe consisted of a cylindrical body topped by a dome, totaling 2.035 meters in height, 1.050 meters in diameter, with a fueled mass of 643.5 kg. Two solar panels, with a total area of 2 square meters, extended radially from the cylinder. A large (over 2 meter diameter) high-gain net antenna was planned to transmit signals from Venus at 8 cm and 32 cm wavelengths. This antenna was attached to the cylinder. A 2.4 meter long omni-directional antenna arm was designed for 1.6 m wavelength transmissions, and a T-shaped antenna was used to transmit signals to Earth at 922.8 MHz at 1 bit/sec. Uplink commands were sent to the spacecraft at 770 MHz at 1.6 bit/sec. The probe was equipped with scientific instruments including a magnetometer attached to the end of a 2 meter boom, ion traps, micrometeorite detectors, and cosmic radiation counters. The dome contained a sphere pressurized at 1.2 atm., which carried a Soviet pennant and was designed to float on the putative Venus oceans after the intended Venus impact. Venera 1 had an on-board mid-course correction engine (although this was not labelled in diagrams of the spacecraft). Temperature control, nominally 30 C, was achieved with thermal shutters. Attitude control was achieved through the use of Sun and star sensors, gyroscopes, and nitrogen gas jets.

Another photo of the Venera 1 model

During the first telemetry session, on February 12, data indicated unstable operation of the system designed to keep the spacecraft permanently oriented to the Sun, needed to generate energy from its solar panels. The spacecraft was programmed so that if such a problem occurred, it would automatically orient itself toward the Sun using gyroscopes, and then shut down non-essential systems. Unfortunately, it automatically shut down its communications system for five days until the next planned communications system, because it detected higher than usual temperatures in the spacecraft. The extra heat was due to the failure of mechanical thermal shutters designed to regulate heat in the vehicle. Despite these problems, the spacecraft responded properly during a communications session on February 17, 1961, at a distance of 1.9 million kilometers when scientific data on interplanetary magnetic fields, cosmic rays, and solar plasma was returned. Unfortunately, controllers were unable to regain contact during a subsequent communications attempt on February 22. A later investigation indicated that the spacecraft had lost its “permanent” solar orientation due to an optical sensor that malfunctioned because of excess heat after the spacecraft’s thermal control system failed. The inert spacecraft eventually passed by Venus on 19–20 May 1961 at a distance of about 100,000 kilometers and entered heliocentric orbit. Data from Venera 1 helped detect plasma flow in deep space.

12 February 1974

Mars 4 and Mars 5 spacecraft. Credit: NPO Lavochkin

On February 12, 1974, Mars 5 spacecraft (M-73S No. 53) entered orbit around Mars, but failed prematurely on February 28, 1974.

Mars 5 was the sister Mars orbiter to Mars 4. The spacecraft was launched by a Proton-K with Block D launch vehicle on July 25, 1973. After mid-course correction burns on August 3, 1973 and February 2, 1974, the spacecraft reached Mars on 12 February 1974 at 15:44:25 UT and was inserted into an elliptical 1760 km x 32,586 km, 24 h 53 min. orbit with an inclination of 35.3 degrees.

Soon after orbital insertion, ground controllers detected the slow depressurization of the main instrument compartment on the orbiter, probably as a result of an impact with a particle during or after orbital insertion. Calculations showed that at the current rate of air loss, the spacecraft would be operational for approximately three more weeks. Scientists drew up a special accelerated science program that included imaging of the surface at 100-meter resolution. Five imaging sessions on 17, 21, 23, 25 and 26 February 1974 produced a total of 108 frames of comprising only 43 usable photographs showing swaths of the area south of Valles Marineris, from 5° N, 330° W to 20° S, 130° W. Both the high-resolution Vega-3MSA and the survey Zufar-2SA TV cameras were used. Additionally, Mars 5 used the OMS scanner to take five panoramas of the surface. Mars 5’s photos, some of which were of comparable quality to those of Mariner 9, clearly showed surface features which indicated erosion caused by free-flowing water.


Composite of images taken by the Soviet Mars 5 spacecraft from Martian orbit on 23 February 1974. Credit: Don Mitchell	‪

Mars 5 collected data for 22 orbits until a loss of pressurization in the transmitter housing ended the mission. The probe's original planned lifetime in Mars orbit had been three months. The probe's gamma ray spectrometer measured the uranium, thorium and potassium content of the surface the probe passed over and found they were similar to igneous rocks on Earth. The exact ratios of the elements varied with the age of the surface. Mars 5's Infrared radiometer reported a daytime surface temperature of between −44 and −2 °C. Night time temperatures were measured at −73 °C. The probe also made a number of observations of Mars's atmosphere. It found an ozone layer at an altitude of 30 kilometres and observed clouds.

Image of Mars taken by Mars 5. Credit: Don Mitchell

12 February 1997

Artist's impression of HALCA satellite and ground-based radio telescopes. Credit: JAXA

On February 12, 1997, HALCA (Highly Advanced Laboratory for Communications and Astronomy) – also known as VSOP (VLBI Space Observatory Programme), MUSES-B, or Haruka – a Japanese radio astronomy satellite, was launched from Kagoshima Space Center by M-V-1 launch vehicle. The satellite carried a wire mesh dish antenna 8 m in diameter as one part of a radio astronomy interferometer, with the other part being any one of a number of ground-based radio telescopes.

The satellite, with a mass of 830 kg, was placed in a highly elliptical orbit with an apogee altitude of 21,400 km and a perigee altitude of 560 km, with an orbital period of approximately 6.3 hours. On February 28, the deployment of the large antenna's main reflection mirror was completed. Full operation as a space VLBI satellite began after technical checkups, such as the establishment of interactive communication link with the tracking station.

HALCA during a solar battery check. Credit: JAXA

Launch of HALCA on board of a M-V-1 rocket. Credit: JAXA

HALCA planned to use three frequency bands, 1.60–1.73 GHz, 4.7–5.0 GHz, and 22.0–22.3 GHz. The sensitivity of the 22 GHz band dropped drastically, however, probably caused by vibration at launch. Observations were thus made by using the 1.6 GHz and 5.0G Hz bands intensively.

Using HALCA, a virtual radio telescope with an aperture of 30,000 km (about three times the earth's radius) was created. Observations of celestial bodies were conducted jointly with radio telescope networks on the ground across the world. The satellite succeeded in observing radio waves from quasar PKS0637-752 with a resolution of 2/10,000 arc sec and a jet from M87 Galaxy with 1/1,000 arc sec resolution.

The satellite made its final VSOP observations in October 2003, far exceeding its 3-year predicted lifespan, before the loss of attitude control. All operations were officially ended in November 2005.

Diagram of the HALCA satellite. Credit: JAXA

Another artist's impression of HALCA. Credit: JAXA

The large image shows M87 as observed with the VLA (Very Large Array), the insert shows observations with the VLBA and HALCA.

12 February 2001

Artist’s impression of the NEAR Shoemaker spacecraft on the surface of Eros. Credit: NASA/Johns Hopkins APL

On February 12, 2001, NEAR Shoemaker spacecraft landed on the surface of the asteroid (433) Eros, the first spacecraft to soft-land on an asteroid. The probe – which was not designed as a lander – survived touchdown and returned data, especially from its gamma-ray spectrometer, for about two weeks. The last contact with the spacecraft was on February 28, 2001.

NEAR Shoemaker was launched on February 17, 1996 – the first in NASA's Discovery Program of low-cost, scientifically focused planetary missions – and became the first spacecraft to orbit an asteroid on February 14, 2000. NEAR spent one year in Eros orbit prior to its final descent. The main goal of the landing was to capture images of Eros at extremely high resolution, potentially improving the resolution by a factor of 10 over the best images (resolutions of about 0.3m per pixel) acquired during the low-altitude flyover on January 28, 2001.

Mosaic of Eros looking down on the north polar region. Credit: NASA/Johns Hopkins APL

Before the descent, the NEAR spacecraft was in a near-circular 34 km by 36 km retrograde orbit. A de-orbit burn of 2.57 m/s performed on February 12 at 15:14 UTC changed the orbit inclination from 180 degrees to 135 degrees relative to Eros' equator. Four additional braking manoeuvres were pre-programmed to execute at fixed intervals during the 4.5-h controlled descent. The time of impact from Doppler tracking was determined to be 19:44:16 UTC. Post-landing analysis indicated a vertical impact velocity of 1.5 to 1.8 m/s and a transverse impact velocity of 0.1 to 0.3 m/s. The touchdown site was determined to be at 35.7° S, 279.5° W, about 500 m from the nominal site, within the large 9-km depression Himeros. All times are spacecraft event times in UTC. On February 12, 2001, Eros was 2.11 astronomical units from Earth corresponding to a one-way light time from the spacecraft to Earth of 17 min 34.5 s.

The spacecraft sent 70 images during the descent. The closest image, from an altitude of 129 m, showed the interior of a 100-m diameter crater at 1-cm resolution. Although telemetry ceased when the spacecraft landed, carrier lock was maintained indicating that NEAR had survived and was still operational. Telemetry was later restored, and it was determined that NEAR was resting on the tips of two solar panels and the bottom edge of the spacecraft's body. Although the mission was scheduled to end on February 14, 2001, NASA decided to extend the mission by 14 days to gather additional gamma-ray spectrometer and magnetometer data. On February 28, commands were sent to place the spacecraft into a hibernational mode. A final attempt to communicate with the spacecraft on December 10, 2002, was unsuccessful.

Last four images of the NEAR descent sequence. Credit: NASA/Johns Hopkins APL/J. Veverka et al.

NEAR Shoemaker's image of asteroid 433 Eros taken from a range of 250 meters. The image is 12 meters across. The cluster of rocks at the upper right measures 1.4 meters across. Credit: NASA/Johns Hopkins APL

The last image of Eros received from NEAR Shoemaker. Taken from a range of 120 meters, it measures 6 meters across. What we can see of the rock at the top of image measures 4 meters across. The streaky lines at the bottom indicate loss of signal as the spacecraft touched down on the asteroid during transmission of this image. Credit: NASA/Johns Hopkins APL

NEAR descent sequence. Credit: NASA/Johns Hopkins APL

See also NEAR Shoemaker: launch, Eros orbit insertion

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On This Day in Space Exploration

February 12

12 February 1947

12 February 1961

12 February 1974

12 February 1997

12 February 2001

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