Parker Solar Probe Breaks Record, Becomes Closest Spacecraft to Sun
Parker Solar Probe now holds the record for closest approach to the Sun by a human-made object. The spacecraft passed the current record of 26.55 million miles from the Sun’s surface on Oct. 29, 2018, at about 1:04 p.m. EDT, as calculated by the Parker Solar Probe team.
The previous record for closest solar approach was set by the German-American Helios 2 spacecraft in April 1976. As the Parker Solar Probe mission progresses, the spacecraft will repeatedly break its own records, with a final close approach of 3.83 million miles from the Sun’s surface expected in 2024.
On this day in 1989 the Galileo spacecraft was launched to explore Jupiter and its moons.
Galileo was an American unmanned spacecraft that studied the planet Jupiter and its moons, as well as several other Solar System bodies. Named after the Italian astronomer Galileo Galilei, it consisted of an orbiter and an entry probe. It was delivered into Earth orbit on October 18, 1989 by Space Shuttle Atlantis. Galileo arrived at Jupiter on December 7, 1995, after gravitational assist flybys of Venus and Earth, and became the first spacecraft to orbit Jupiter. It launched the first probe into Jupiter, directly measuring its atmosphere. Despite suffering major antenna problems, Galileo achieved the first asteroid flyby, of 951 Gaspra, and discovered the first asteroid moon, Dactyl, around 243 Ida. In 1994, Galileo observed Comet Shoemaker–Levy 9’s collision with Jupiter.
Jupiter’s atmospheric composition and ammonia clouds were recorded, the clouds possibly created by outflows from the lower depths of the atmosphere. Io’s volcanism and plasma interactions with Jupiter’s atmosphere were also recorded. The data Galileo collected supported the theory of a liquid ocean under the icy surface of Europa, and there were indications of similar liquid-saltwater layers under the surfaces of Ganymede and Callisto. Ganymede was shown to possess a magnetic field and the spacecraft found new evidence for exospheres around Europa, Ganymede, and Callisto. Galileo also discovered that Jupiter’s faint ring system consists of dust from impacts on the four small inner moons. The extent and structure of Jupiter’s magnetosphere was also mapped.
On September 21, 2003, after 14 years in space and 8 years in the Jovian system, Galileo’s mission was terminated by sending it into Jupiter’s atmosphere at a speed of over 48 kilometers per second (30 mi/s), eliminating the possibility of contaminating local moons with terrestrial bacteria. (source)
On August 8, 1978, the Pioneer Venus Multiprobe spacecraft launched to study Venus, a planet that has an atmosphere 100 times denser than Earth’s atmosphere and is hotter than the melting point of zinc and lead. Pioneer Venus Multiprobe was composed of five components: the main spacecraft, the large probe and three identical small probes named North, Day and Night. Built by the Hughes Company in El Segundo, California, and launched on an Atlas-Centaur rocket from Cape Canaveral Air Force Station in Florida, the Pioneer Venus Multiprobe project was managed by NASA’s Ames Research Center in California’s Silicon Valley.
Carrying seven experiments and fitted with a parachute to slow its descent into the atmosphere, the large probe studied the composition of Venus’ atmosphere and clouds. In addition, the large probe measured the distribution of infrared and solar radiation. The three small probes were designed without parachutes, each carrying six experiments. Each probe targeted different parts of Venus. North entered Venus at the high northern latitudes, Night targeted the night side at mid-southern latitudes, and Day targeted the day side at mid-southern latitudes. The main spacecraft carried an additional two experiments designed to study Venus’ upper atmosphere. The five probes collected detailed information about atmospheric composition, circulation and energy balance.
The large probe separated from the main spacecraft 123 days after launch, on November 16, followed by the small probes on November 20, reaching and entering Venus’ atmosphere December 9. While not expected to survive their fiery descent into the dense Venusian atmosphere, all four of the probes transmitted data down to the surface with the Day probe transmitting from the surface for over an hour.
A ground-penetrating radar aboard the European Space Agency’s Mars Express satellite has found evidence for a pool of liquid water, a potentially habitable environment, buried under layers of ice and dust at the red planet’s south pole.
“This subsurface anomaly on Mars has radar properties matching water or water-rich sediments,” said Roberto Orosei, principal investigator of the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, or MARSIS, lead author of a paper in the journal Science describing the discovery.
The conclusion is based on observations of a relatively small area of Mars, but “it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered,” added Orosei.
Scientists have long theorised the presence of subsurface pools under the martian poles where the melting point of water could be decreased due to the weight of overlying layers of ice. The presence of salts in the Martian soil also would act to reduce the melting point and, perhaps, keep water liquid even at sub-freezing temperatures.
Earlier observations by MARSIS were inconclusive, but researchers developed new techniques to improve resolution and accuracy.
“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low,” said Andrea Cicchetti, MARSIS operations manager.
“We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset. Now we see things that simply were not possible before.”
MARSIS works by firing penetrating radar beams at the surface of Mars and then measuring the strength of the signals as they are reflected back to the spacecraft.
The data indicating water came from a 200-kilometre-wide (124-mile-wide) area that shows the south polar region features multiple layers of ice and dust down to a depth of about 1.5 kilometres (0.9 miles). A particularly bright reflection below the layered deposits can be seen in a zone measuring about 20 kilometres (12 miles) across.
Orosei’s team interprets the bright reflection as the interface between overlying ice and a pool or pond of liquid water. The pool must be at least several centimetres thick for the MARSIS instrument to detect it.
“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential,” says Dmitri Titov, ESA’s Mars Express project scientist.
The discovery is significant because it raises the possibility, at least, of potentially habitable sub-surface environments.
“Some forms of microbial life are known to thrive in Earth’s subglacial environments, but could underground pockets of salty, sediment-rich liquid water on Mars also provide a suitable habitat, either now or in the past?” ESA asked in a statement. “Whether life has ever existed on Mars remains an open question.”
The Venera series space probes were developed by the Soviet Union between 1961 and 1984 to gather data from Venus, Venera being the Russian name for Venus. As with some of the Soviet Union’s other planetary probes, the later versions were launched in pairs with a second vehicle being launched soon after the first of the pair.
Ten probes from the Venera series successfully landed on Venus and transmitted data from the surface of Venus, including the two Vega program and Venera-Halley probes. In addition, thirteen Venera probes successfully transmitted data from the atmosphere of Venus.
Among the other results, probes of the series became the first human-made devices to enter the atmosphere of another planet (Venera 4 on October 18, 1967), to make a soft landing on another planet (Venera 7 on December 15, 1970), to return images from the planetary surface (Venera 9 on June 8, 1975), and to perform high-resolution radar mapping studies of Venus (Venera 15 on June 2, 1983). The later probes in the Venera series successfully carried out their mission, providing the first direct observations of the surface of Venus. Since the surface conditions on Venus are extreme, the probes only survived on the surface for durations varying between 23 minutes (initial probes) up to.
Ceresis the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars’ orbit. Its diameter is approximately 945 kilometers (587 miles), making it the largest of the minor planets within the orbit of Neptune. The 33rd-largest known body in the Solar System, it is the only dwarf planet within the orbit of Neptune. Composed of rock and ice, Ceres is estimated to compose approximately one third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own gravity (though detailed analysis was required to exclude 4 Vesta). From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, peaking once every 15 to 16 months, hence even at its brightest it is too dim to be seen with the naked eye except under extremely dark skies.
Dawn revealed that Ceres has a heavily cratered surface; nevertheless, Ceres does not have as many large craters as expected, likely due to past geological processes. An unexpectedly large number of Cererian craters have central pits, perhaps due to cryovolcanic processes, and many have central peaks. Ceres has one prominent mountain, Ahuna Mons; this peak appears to be a cryovolcano and has few craters, suggesting a maximum age of no more than a few hundred million years. A later computer simulation has suggested that there were originally other cryovolcanoes on Ceres that are now unrecognisable due to viscous relaxation. Several bright spots have been observed by Dawn, the brightest spot (“Spot 5”) located in the middle of an 80-kilometer (50 mi) crater called Occator. From images taken of Ceres on 4 May 2015, the secondary bright spot was revealed to actually be a group of scattered bright areas, possibly as many as ten. These bright features have an albedo of approximately 40% that are caused by a substance on the surface, possibly ice or salts, (with the realization of new studies are now likely deposits of salt composed mainly of hydrated magnesium sulphate). reflecting sunlight.