February 28 – Discoverer 1

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.

Asteroid 193 Ambrosia was discovered today in 1879 by J Coggia. Unlike Discoverer 1, above, it has no trouble maintaining orbit, and 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.

Thetis Annoints Achilles with Ambrosia (Johann Balthasar Probst)
Thetis Annoints Achilles with Ambrosia (Johann Balthasar Probst)

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.


February 27 – Discoverer 38

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.

KH-4 CORONA-M (of the type used for the Discoverer 38 mission).  (image credit: Giuseppe De Chiara)
KH-4 CORONA-M (of the type used for the Discoverer 38 mission). (image credit: Giuseppe De Chiara)


February 26 – Defining Minor Planets: A Major Headache

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 PLANETS in 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.

Ceres from the DAWN spacecraft (image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
Ceres from the DAWN spacecraft (image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

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).


February 25 – Asteroid 265 Anna

February 25, 1887  –  265 Anna

Asteroid 265 Anna, a 24 km wide main belt asteroid of unknown spectral type, was discovered from Vienna by Austrian astronomer Johann Palisa.  It is thought to have been named after the daughter of Edmund Weiss, director of the Vienna Observatory.

Astronomer Edmund Weiss: Anna's Dad?
Astronomer Edmund Weiss: Anna’s Dad?

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.


1971  –  Launch of Cosmos 397.


February 24 – Shuttle ‘Discovery’ Retires

February 24, 2011 – Last Flight of Shuttle Discovery (STS133)

STS133, led by commander Steven Lindsey on his fifth flight, was the 39th and last mission for Discovery, and the 133rd flight of the shuttle fleet.

This Way Up: the crew of STS-133 (image credit: NASA)
This Way Up: the crew of STS-133 (image credit: NASA)

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.

Also today, we celebrate the launch by the USA, on 24 February 1968, of Mariner 6.

Mariner 6 (or is it 7?) (Image: NASA)
Mariner 6 (or is it 7?) (Image: NASA)

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.

NASA Exceptional Bravery Medal
NASA Exceptional Bravery Medal

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.

1987 – Discovery, in the Large Magellanic Cloud, of supernova 1987A from the Las Campanas Observatory in Chile.


February 22 – Adolphe Quetelet

Today we wish a happy birthday to Lambert Adolphe Jacques Quetelet, born 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).

Adolphe Quetelet: famous Belgian.
Adolphe Quetelet: famous Belgian.

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.

1966   ⇒   Launch of Cosmos 110.


February 21 – Hakucho Takes Flight

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 (image credit: NASA)
Hakucho (image credit: NASA)

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.

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.

1938   ⇒   Death of George Ellery Hale.


February 20 – Mercury-Atlas 6

Mercury-Atlas 6 (mission name Friendship 7) was launched from Cape Canaveral at 9:47am EST this day in 1962 after several delays caused by bad weather and leaky fuel tanks.

John Glenn (image credit: NASA)
John Glenn (image credit: NASA)

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.

2001  –  ODIN

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 160 Una, 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 Glauke was discovered by Robert Luther, 1890.


February 19 – Two Discoverers Launched (kind of)


Discoverer 10 was one of the USA’s shortest-lived spy satellites.  The aim of the Discoverer program was basically to watch the Russians to see how quickly they were developing their long-range bombing and missile launching capability.  Discoverer 10 was launched from Vandenburg Air Force Base on February 19 at a quarter past eight in the evening, and reached approximately 6000 metres in 59 seconds before being destroyed from the ground after veering off-course.


Okay, maybe not launched, but certainly born.  Today is happy birthday to Nicolaus Copernicus, born this day in the Polish city of Toruń in 1473.  His book On the Revolutions of the Celestial Spheres was published in 1543, the last year of his life, although he had been working on the theories within it for some years, and revolutionized (pun intended) our view of the solar system.  Copernicus made the giant leap of putting the Sun at the centre of the universe, and explained that the apparent motion of both it, and the other “celestial spheres” (including the retrograde motion of planets) was due to the motion of the Earth and other bodies around the Sun.


Copernicus’ masterpiece was a heavy read, which meant demand was low.  It was also potentially blasphemous, which assured it a place in the Index Librorum Prohibitorum (List of Prohibited Books) of the Catholic Church from 1616 to 1758.   Kudos to Pope Benedict XIV for removing the book from the Index.



February 18 – Pluto

I feel sorry for Pluto. When I was younger it was the ninth biggest planet in the solar system, but unfortunately is now (probably) only the second biggest “dwarf planet” following the discovery of minor-planet 136199 Eris by the Palomar Observatory on January 5th 2005. This discovery encouraged an acceleration of the debate over whether or not Pluto should ever have been called a planet, the result being that the IAU published their Definition of a Planet in the Solar System on August 24th 2006. So I suppose that’s the day on which Pluto stopped being a planet, and became a Kuiper Belt Object. And as if that weren’t damage enough for Pluto’s image, there is still a debate going on as to whether Pluto and Charon should be re-classified as a binary system. At the moment Charon is a moon of Pluto; but the centre of their combined mass doesn’t lie within either body, so strictly speaking it should get higher billing.

On the upside, Pluto does get its own Disney character, and lends its name to both plutoids (anything beyond the orbit of Neptune that has managed to attain a roughly spherical shape) and plutinos (anything in the above group that orbits the Sun twice in the same time it takes Neptune to make it round three times).

Pluto was discovered on February 18th 1930 by Clyde Tombaugh from Illinois. Tombaugh was a prolific discoverer of variable stars, and also of asteroids, many of which he found while searching for Pluto. But Pluto will always be his claim to fame, and following his death in 1997 a small quantity of his ashes were sent on their way out there aboard the New Horizons probe, which arrived at the ex-planet on July 14th 2015 to a blaze of publicity, and began sending back fabulous snapshots.

Pluto from the New Horizons probe (image credit: NASA/APL/SwRI)
Pluto from the New Horizons probe (image credit: NASA/APL/SwRI)

And not before time, as you can see from the second photograph (below); because close-ups of Pluto from the enormous distance of the Earth don’t reveal a great deal of detail.

Pluto and Charon (image: NASA)
Pluto and Charon, pre-New Horizons (image: NASA)

As well as the aforementioned Charon, Pluto has four other moons: Nix, Hydra, Kerberos and Styx. All moons of Pluto are named in accordance with the convention that they are mythological, and have some association with their parent (Hydra, for example, was the nine-headed guardian of an entrance to the underworld).

Surface detail of Pluto from New Horizons (image credit: NASA)
Surface detail of Pluto from New Horizons (image credit: NASA)

As I just mentioned, Pluto is a Kuiper Belt object (KBO). The Kuiper belt, (rhymes with sniper, not kipper, although I have to admit that I do find the concept of a kipper belt rather appealing) or, to give it its full name the Edgeworth-Kuiper Belt, stretches from about 30 to 50 AU from the Sun, and contains an enormous number of mostly smallish bodies (trans-Neptunian Objects, or TNOs) left over from the formation of the Solar System.

A Selection of KBOs (image: NASA)
A Selection of KBOs (image: NASA)

Why Edgeworth gets edged out in popular literature while Kuiper gets the kudos is something I might know more about by the time his birthday comes around (Feb 26th, 1880). Neither of them correctly predicted what the belt was like anyway, so it’s anybody’s guess.

Anyhoo, there are thought to be as many as 100,000 TNOs within the belt with a diameter of over 100km (which is why I say “smallish” not “small”) and, because Pluto is now a member, everybody knows the name of at least one.

Results from New Horizons are changing our view of Pluto for ever. It now see that a crust of water ice might be acting in place of a bedrock, supporting mountains made of frozen nitrogen and methane. It also seems that Pluto might, somehow, be still geologically active. We need to visit again!

February 18th, 1977 was the day on which the space shuttle Enterprise made her first “attached” flight. Strictly speaking, I suppose, this wasn’t the maiden flight of a shuttle, as Enterprise was securely strapped to the back of a specially adapted Boeing 747 for the duration. I now know that she didn’t have any engines or a heat shield, and was therefore incapable of actually flying in space, but at the time I was young(er), and mightily impressed (and it was the first time a shuttle’s wheels had been higher than the hangar roof, so it counts). I was even more impressed when Enterprise was flown, again attached to the 747, over the family home at Brown Edge, Staffordshire, six years later as part of a promotional tour of Europe, drumming up satellite launching business for NASA.