Asteroid 193 Ambrosia was discovered today in 1879 by J Coggia. It sweeps majestically round the Sun every 4.2 years, rotating once every 8.6 hours as it does so. Ambrosia was named after the food of the gods in Greek mythology.
Asteroid 184 Dejopeja, discovered one year earlier by Johann Palisa, and named after a nymph of Roman mythology, Deiopeia, takes slightly longer to get round the Sun: 5.67 years. These timings are, obviously, all measured from an Earth perspective for the purpose of helping to predict where the asteroid might be at a particular time. From the point of view of anyone living on the asteroids, it would of course take one year to complete an orbit, and one day to complete a rotation.
Discoverer 1 was launched at 1:49pm on February 28, 1959, on board Thor-Agena rocket DM-18 from Vandenberg Air Force Base. It was a prototype surveillance satellite, but was only a test flight, so it had no actual equipment on board. The plan for Discoverer 1 was to achieve a polar orbit, but, after a successful main engine burn and separation, something went wrong, and all contact was lost eight and a half minutes into the flight.
Whether or not Discoverer 1 made it into orbit, for however long or short a time, is open to debate. The most likely scenario is that it failed to reach the required altitude and either splashed down in the South Pacific or crashed into Antarctica. But the fact remains that, at a time when there was significantly less space junk up there than there is now, something was detected by Jodrell Bank, once, in about the right place, at about the right time. So Discoverer 1 may have made it after all.
Launched on February 27th, 1962, from Vandenburg Air Force Base by the Thor launch vehicle, Discoverer 38 had a wide variety of experiments on board, including some which were later recovered in mid-air on their way back to Earth. The experiments in the re-entry capsule mainly involved measuring the effects of exposure to radiation and the environment beyond our atmosphere. Some organic matter (human tissue, algae, molds, etc) were included to see how they stood up to being in space. The re-entry capsule was detached and recovered successfully after 65 orbits, with the rest of the craft burning up on re-entry on March 21st.
Discoverer 38 was the last of the US series of Corona spy satellites to use the “Discoverer” cover name. The name was used to help disguise the fact that, while carrying out scientific study at high altitudes was undoubtedly of great importance to the US government, no way was it as important as taking photographs of the USSR, which was the other part of Discoverer 38’s mission.
1842 – Birth of Nicolas Camille Flammarion, astronomer and science fiction author, in Montigny-le-Roi, France.
1880 – Birth of Kenneth Edgeworth, the first person to propose the existence of what would eventually become known as the Kuiper Belt.
1965 – Launch of the experimental meteorological satellite Cosmos 58 by the USSR.
Today, as we have no “asteroid” discoveries to discuss, we’re going to have a crash course in a couple of groups of large flying things that used to be called asteroids, but are now commonly known as minor planets. The term refers to all sorts of things, and can be broadly defined as anything orbiting the Sun that isn’t a planet or a comet. The terminology, however, is confused and confusing, and unlikely to become any clearer as more bodies are discovered beyond the traditional confines of the Solar System. So nowadays you have to decide whether you’re talking about a dwarf planet, an asteroid, a trojan, a centaur, a comet, a small Solar System body, a Kuiper Belt object or a trans-Neptunian object.
The IAU prefer the term small Solar System body for comets and anything too small to use gravity to maintain an ellipsoidal shape, and have done so since their General Assembly of 2006 (IAU 2006), the same one that decided the fate of Pluto. According to this classification, anything that is not a planet, but which is able to become roughly planet-shaped is a dwarf planet.
So now we have to briefly ask “What is a planet?” well, according to Resolution 5A of IAU 2006 a planet has to (a) be orbiting the Sun, (b) be able to use its own gravity to keep a nearly round shape, and (c) be sufficiently well-developed to have “cleared the neighbourhood“. This might be a new phrase to you, but all it means is that the object under consideration has become the dominant one in its orbit, so that there is nothing left nearby of comparable size (except possibly its own satellites). A dwarf planet meets conditions (a) and (b), but not (c).
So, let’s have a quick look at a couple of the various types of non-planets (I don’t want to drive you away by tackling them all at once).
There are presently known to be five DWARF PLANETSin the Solar System. These are Pluto, Ceres, Eris, Haumea and Makemake. Several further trans-Neptunian objects (including Sedna and Quaoar) may well swell their ranks shortly, but their size and distance makes pinning them down difficult. However, as the outer reaches of the Solar System are explored it is thought that hundreds, possibly thousands, more will turn up. It is probably only our inability to see beyond the Kuiper Belt that is keeping the numbers down.
I’m not fond of the term dwarf planet, as it suggests that these are small planets, whereas the idea was, I believe, that they aren’t planets at all. For this reason I would maybe prefer the older term planetoid. The Japanese have got the right idea: their name for dwarf planets, junwakusei, can be translated as “almost a planet”, which I like almost as much as the suggestion of Alan Stern and Harold Levison from their paper to the IAU in 2000. They adopted the words überplanet for the big eight, and unterplanet for the rest. TROJANS are interesting characters. I don’t want to get bogged down explaining Lagrangian points and barycentres (yet) so I’ll just say that a trojan shares an orbit with another (larger) body at the Lagrangian points, approximately 60° ahead of or behind it. We have more interchangeable terminology here: a trojan can also be called a Lagrangian object, and the Lagrangian points are sometimes called trojan points. Saturn has a great collection of trojan moons: they are (i) Telesto and Calypso (trojans of Tethys), and (ii) Helene and Polydeuces(trojans of Dione).
Jupiter also has a large collection of trojans, traditionally named after the two camps of the Trojan Wars. Greek trojans are located at one Lagrangian point, and Trojan trojans are at the other. There are two exceptions to this rule (because their discovery pre-dates it): they are 617 Patroclus ( a Greek, but with the Trojans), and 624 Hektor (a Trojan with the Greeks). I never liked Hektor much when I read the Iliad, so this doesn’t surprise me in the slightest.
Next time I get a quiet day I’ll move onto centaurs and Kuiper Belt objects (if I remember).
Asteroid 265 Anna, a 24 km wide main belt asteroid of unknown spectral type, was discovered from Vienna on February 25th, 1887, by Austrian astronomer Johann Palisa. It is thought to have been named after the daughter of Edmund Weiss, director of the Vienna Observatory.
Anna takes 1,375 days to orbit the Sun, and while she’s doing so she varies quite a lot in distance from our star, from 1.77 AU at perihelion (closest) to 3.06 AU at aphelion (farthest away).
February 25, 1892 – 324 Bamberga
Five years later, on this day in 1892, Palisa discovered asteroid 324 Bamberga. It is a main belt asteroid, the brightest of its class (C-type), and the tenth brightest overall, reaching magnitude +8 when at opposition near perihelion.
Johann Palisa was a prolific discoverer of asteroids by anyone’s standards, finding 122 over a period of just under 50 years. This made him the most successful visual asteroid spotter of all time. He was only surpassed when photography became the main method of discovery.
Today we celebrate the launch by the USA, on 24 February 1968, of Mariner 6.
Mariner 6 was half of a double-act with Mariner 7, launched 31 days later. The aim was to study the surface of Mars from close fly-bys, with a view to facilitating future missions. Part of the job, therefore, was to explore how to keep spacecraft working for long periods far from the Sun. The remit of Mariner 6 also included the provision of data in preparation for the arrival of Mariner 7.
Two of the ground crew who worked on the Atlas/Centaur launch vehicle for this mission earned their money several times over in the build-up to the launch by narrowly averting the collapse of the whole structure when they noticed a pressurization fault. They were both awarded medals for bravery by NASA, as the Atlas would probably have collapsed on top of them had they not been successful.
Between them, Mariners 6 and 7 returned over 200 photographs of the Martian surface, and together they covered 20% of the planet. They were also used to measure ultraviolet and infrared levels, and discovered that the southern polar icecap is mostly carbon dioxide.
STS133, led by commander Steven Lindsey on his fifth flight, launched on February 24th, 2011, and was the 39th and last mission for the space shuttle Discovery. It was the 133rd flight of the shuttle fleet.
The main objectives of the mission were the delivery of a new multipurpose module, Leonardo, and an external stowage platform, to the International Space Station. Included in the cargo within Leonardo was Robonaut 2, a three-foot high (from waist to head – it has no legs) robotic astronaut, the first humanoid robot in space, taken aboard the ISS to test how such robots can be used in the unusual environment of a space station.
The crew of 6 ended their mission on March 11th, having spent almost nine days docked with the ISS. Their commander, Steven Lindsey, was a real shuttle veteran, on his fifth and final flight, spending over 1500 hours in space.
1987 – Discovery, in the Large Magellanic Cloud, of supernova 1987A from the Las Campanas Observatory in Chile.
Today we wish a happy birthday to Lambert Adolphe Jacques Quetelet, born in Ghent (at that time part of the French Republic) on February 22nd 1796. Quetelet was many things: mathematician, statistician, sociologist, criminologist, meteorologist, and the man who persuaded King William I to found the Royal Observatory of Belgium at Saint-Josse-ten-Noode (a region of Brussels).
Quetelet was also the man who gave us the concept of the Body Mass Index (BMI), or Quetelet Index, as it was known until the 1970s.
1900 ⇒ Main belt asteroid 453 Tea discovered by Auguste Charlois. The reason behind the choice of name remains a mystery. Tea is a member of the Flora family of S-type asteroids, from where the Chicxulub impactor (the big one that probably caused the extinction of the dinosaurs) is thought to have originated.
Hakucho (Japanese for “swan”) was Japan’s first x-ray telescope, launched on February 21st 1979, despite having the pre-launch name “CORSA-B”, which suggests it might, at best, be the second. The original CORSA telescope had failed to launch in February 1976, and Hakucho was a replacement.
Hakucho carried eleven x-ray counters, providing readings for the three onboard experiments. Its main work was the study of transient phenomena, especially x-ray bursts, and high on the list of its successes was the discovery of the transient x-ray binary neutron star, Cen X-4.
Hakucho’s experiments were on soft, hard and very hard x-rays. The hardness of an x-ray is based upon its energy; soft x-rays have lower energy than harder ones. It’s the harder ones they use in hospitals and airports.
Hakucho’s active life ended on April 16th, 1985.
1906 ⇒ Discovery of main belt asteroid 586 Thekla by Max Wolf. Thekla is a T-type asteroid of approximately 82 km in diameter. It is named after an early Christian saint who was saved (by a storm) from being burned at the stake.
Mercury-Atlas 6 (mission name Friendship 7) was launched from Cape Canaveral at 9:47am EST this day in 1962after several delays caused by bad weather and leaky fuel tanks.
The photograph shows astronaut John Herschel Glenn Jr practicing how to get into the Mercury spacecraft. If it was me I’d be too busy practicing how to get out to pose for this one.
Spaceflights didn’t tend to last long in those days, so today is also the anniversary of the end of this particular mission. Glenn was in flight for less than 5 hours (or should that be fewer than?), but in that time he managed to clock up over 65,000 miles.
During his 17,000 mph flight Glenn was forced to abandon the automatic control system following a fault, and was confronted by an erroneous error message suggesting that part of the heatshield was loose. After which, he was expected to land his tin can in the middle of the Atlantic. Whatever they paid him, it wasn’t enough.
1983 – TENMA x-ray telescope launched.
This was a Japanese telescope, and the name “Tenma” is Japanese for Pegasus. It had a short life, re-entering the atmosphere on January 19, 1989. TENMA carried a Gas Scintillation Proportional Counter. “What’s that?” I don’t hear you cry. Well, it’s a chamber filled with an unreactive gas that can be ionized by x-rays. Electrons of the gas then emit UV photons whose energy can be measured and converted into a measure of the energy of the x-rays.
1993 – ASCA x-ray telescope launched.
ASCA = Advanced Satellite for Cosmology and Astrophysics. ASCA was another Japanese x-ray telescope, their fourth. It was the first mission to use CCDs for x-ray astronomy.
Our last launch of the day isn’t Japanese. As you might expect from the name, ODIN has a Scandinavian origin (Swedish in this case). Launched from Svobodny in eastern Russia on this day in 2001, Odin’s raison d’être is to study ozone depletion and search for water and oxygen in interstellar space. To enable it to do this it carries a 1.1 metre telescope and a spectrograph called OSIRIS (Optical Spectrograph and Infrared Imaging System). As far as I know it’s still in use (but the Swedish National Space Board website needs updating).
Also today, asteroid 160Una, a C-type in the main belt, was discovered by C H F Peters in 1876. The name comes from The Faerie Queene by Edmund Spencer.
And now it is empassioned so deepe,
For fairest Vnaes sake, of whom I sing,
That my fraile eyes these lines with teares do steepe,
To thinke how she through guilefull handeling,
Though true as touch, though daughter of a king,
Though faire as euer liuing wight was faire,
Though nor in word nor deede ill meriting,
Is from her knight diuorced in despaire
And her due loues deriu’d to that vile witches share.
“The Faerie Queene”, Edmund Spencer, 1596.
And finally, asteroid 288 Glaukewas discovered by Robert Luther, 1890.