Feb 252018

Today is the birthday (1670) of Maria Margaretha Kirch (née Winckelmann), a Saxon astronomer, and one of the most famous astronomers of her time due to her observations of the conjunction of the sun with Saturn, Venus, and Jupiter. She was also the first woman astronomer to discover a comet. Maria Kirch could well serve as the poster child of what women in the 17th and 18th centuries had to endure to be recognized as competent scientists.

Kirch, was born in Panitzsch, near Leipzig, and educated from an early age by her father, a Lutheran minister, who believed that she deserved an education equivalent to that given to young boys of the time. By the age of 13 she was an orphan, but she had received a general education from her brother-in-law Justinus Toellner and the well-known astronomer Christoph Arnold, who lived nearby. Her education was continued by her uncle. She continued studying with Arnold, a self-taught astronomer who worked as a farmer in Sommerfeld, near Leipzig. She became Arnold’s unofficial apprentice and later his assistant, living with him and his family.

Through Arnold, Maria met the famous German astronomer and mathematician Gottfried Kirch, who was 30 years her senior. They married in 1692, later having four children, all of whom followed in their parents’ footsteps by studying astronomy. In 1700 the couple moved to Berlin, because the elector/ruler of Brandenburg, Frederick III, later Frederick I of Prussia, had appointed Gottfried Kirch as his royal astronomer.

Gottfried Kirch gave his wife further instruction in astronomy, as he did for his sister and many other students. Women were not allowed to attend universities in Germany, but the actual work of astronomy, and the observation of the heavens, took place largely outside the universities. Thus Kirch became one of the few women active in astronomy in the early 18th century. She became widely known as Maria Kirchin, the feminine version of the family name. It was not unheard of in the Holy Roman Empire for a woman to be active in astronomy at the time. Maria Cunitz, Elisabeth Hevelius and Maria Clara Eimmart had been active astronomers in the 17th century.

Through an edict, Friedrich III introduced a monopoly for calendars in Brandenburg, and later Prussia, imposing a calendar tax. The income from this monopoly was to pay astronomers and members of the Berlin Academy of Sciences which Friedrich III founded in July 1700. Friedrich III also went on to build an observatory, which was inaugurated in January 1711. Assisted by his wife, Gottfried Kirch prepared the first calendar of a series, entitled Chur-Brandenburgischer Verbesserter Calender Auff das Jahr Christi 1701, which became very popular. Calendars and almanacs were popular, not only because they indicated the dates for Easter and related movable celebrations, but also because they gave astronomical information, as well as general knowledge concerning science and other matters.

Maria and Gottfried worked together as a team. She moved on from her position as Arnold’s apprentice, to become assistant to her husband. Her husband had studied astronomy at the University of Jena and had served as apprentice to Johannes Hevelius. At the academy she worked as his unofficial, but acknowledged, assistant. Women’s positions in the sciences was akin to their position in the guilds, valued but subordinate. Together they made observations and performed calculations to produce calendars and ephemerides. From 1697, the Kirchs also began recording weather information. The data collected by the Kirchs was not only used to produce calendars and almanacs, but was also useful for navigation. The academy in Berlin handled sales of their calendars.

During the first decade of her work at the academy as her husband’s unofficial assistant, Kirch observed the heavens, every evening starting at 9pm. During such a routine observation on 21st April 1702 she discovered the so-called “Comet of 1702” (C/1702 H1). In his notes from that night her husband recorded:

Early in the morning (about 2:00 am) the sky was clear and starry. Some nights before, I had observed a variable star and my wife (as I slept) wanted to find and see it for herself. In so doing, she found a comet in the sky. At which time she woke me, and I found that it was indeed a comet. I was surprised that I had not seen it the night before.

Germany’s only scientific journal at the time Acta eruditorum was in Latin. Kirch’s subsequent publications in her own name were all in German. At the time her husband did not hold an independent chair at the academy and the Kirchs worked as a team on common problems. The couple observed the heavens together, he observed the north and she the south. Kirch’s publications, which included her observations on the Aurora Borealis (1707), the pamphlet “Von der Conjunction der Sonne des Saturni und der Venus” (on the conjunction of the sun with Saturn and Venus) (1709), and the approaching conjunction of Jupiter and Saturn in 1712 became her lasting contributions to astronomy. Before her, the only women astronomer in the Holy Roman Empire that had published under her own name had been Maria Cunitz. The family friend and vice-president of the academy, Alphonse des Vignoles said in Kirch’s eulogy: “If one considers the reputations of Frau Kirch and Frau Cunitz, one must admit that there is no branch of science… in which women are not capable of achievement, and that in astronomy, in particular, Germany takes the prize above all other states in Europe.”

In 1709 academy president Gottfried von Leibniz presented her to the Prussian court, where Kirch explained her sightings of sunspots. He said about her:

She is a most learned woman who could pass as a rarity. Her achievement is not in literature or rhetoric but in the most profound doctrines of astronomy. I do not believe that this woman easily finds her equal in the science in which she excels. She favors the Copernican system, like all the learned astronomers of our time. And it is a pleasure to hear her defend that system through the Holy Scripture in which she is also very learned. She observes with the best observers and knowns how to handle marvelously the quadrant and the telescope.

After her husband died in 1710, Kirch attempted to assume his place as astronomer and calendar maker at the Royal Academy of Sciences. Despite her petition being supported by Leibniz, the president of the academy and the executive council of the academy rejected her request for a formal position saying that “what we concede to her could serve as an example in the future.” God forbid that appointing a woman would set a precedent !! In her petition Kirch set out her qualifications for the position. She argued that she was well qualified because she had been instructed by her husband in astronomical calculation and observation. She emphasized that she had engaged in astronomical work since her marriage and had worked at the academy since her husband’s appointment 10 years earlier. In her petition Kirch said that “for some time, while my dear departed husband was weak and ill, I prepared the calendar from his calculations and published it under his name”. For Kirch an appointment at the academy would have not been just a mark of honour, but was vital in securing an income for herself and her children. In her petition she said that her husband had not left her with means of support. The guild tradition of the time did establish a legitimate claim for Kirch to take over her husband’s position after his death. But these traditions were not followed by the new institutions of science.

While Kirch had carried out important work at the academy, she did not have a university degree, which at that time nearly every member of the academy had. But the academy secretary Johann Theodor Jablonski also cautioned Leibniz,

. . . that she be kept on in an official capacity to work on the calendar or to continue with observations simply will not do. Already during her husband’s lifetime the academy was burdened with ridicule because its calendar was prepared by a woman. If she were now to be kept on in such a capacity, mouths would gape even wider.

Leibniz was the only member of the academy council who supported her appointment. In one of the last council meetings he presided over before leaving Berlin in 1711 Leibniz tried to secure financial assistance for Kirch. Kirch was of the opinion that her petitions were denied due to her gender. This position is supported by the fact that Johann Heinrich Hoffmann, who had little experience, was appointed to her husband’s place instead of her. Hoffmann soon fell behind with his work and failed to make required observations. It was even suggested that Kirch become his assistant. Kirch wrote “Now I go through a severe desert, and because… water is scarce… the taste is bitter”. However, she was admitted by the Berlin Academy of Sciences.

In 1711, she published “Die Vorbereitung zug grossen Opposition,” a well-received pamphlet in which she predicted a new comet, followed by a pamphlet concerning Jupiter and Saturn. In 1712 Kirch accepted the patronage of Bernhard Friedrich von Krosigk, who was an enthusiastic amateur astronomer, and began work in his observatory. She and her husband had worked at Krosigk’s observatory while the academy observatory was being built. At Krosigk’s observatory she reached the rank of master astronomer.

After Baron von Krosigk died in 1714 Kirch moved to Danzig to assist a professor of mathematics for a short time before returning. In 1716 Kirch and her son, who had just finished university, received an offer to work as astronomers for the Russian czar Peter the Great, but preferred to remain in Berlin where she continued to calculate calendars for locales such as Nuremberg, Dresden, Breslau, and Hungary.

Kirch had trained her son Christfried Kirch and daughters Christine Kirch and Margaretha Kirch to act as her assistants in the family’s astronomical work, continuing the production of calendars and almanacs as well as making observations. In 1716 her son Christfried and Johann Wilhelm Wagner were appointed observers at the academy observatory following Hoffmann’s death. Kirch moved back to Berlin to act as her son’s assistant together with her daughter Christine. She was once again working at the academy observatory calculating calendars. Academy members complained that she took too prominent a role and was too visible at the observatory when strangers visit. Kirch was ordered to “retire to the background and leave the talking to… her son.” She refused to comply and was forced by the academy to give up her house on the observatory grounds.

Kirch continued working in private and died of a fever in Berlin on the 29th December 1720.

Kirch’s home town, Leipzig, is famous for many dishes including Leipziger Allerei (Leipzig Hodgepodge). It is basically a vegetable stew enriched with crayfish and butter. The latter are often omitted in modern versions. Here is a traditional version.

Leipziger Allerei


9 oz/250 g carrots
9 oz/250 g kohlrabi
9 oz/250 g asparagus
9 oz/250 g cauliflower
9 oz/250 g morels
18 oz/500 g fresh peas in pods
vegetable broth
4 crayfish
10 tbsp/150 g butter at room temperature
3 eggs
⅛ tsp nutmeg (or mace)
dried bread crumbs
1.7 oz/50 g flour
salt and pepper


Clean and peel the carrots and kohlrabi and cut them evenly into long strips. Shell the peas. Cook these three vegetables together in salted water until they are barely al dente.

Peel the white asparagus, cut the spears into pieces about 2”(5 cm) long. Simmer them in a light vegetable broth.

Cut the cauliflower into florets and cook in milk, adding butter and salt to taste.

Cut the morels into halves and sauté in butter.

Boil the crayfish, and split into pieces, carefully removing the meat from the tails. Rub the head of the crayfish with salt.

Whisk about 2 ounces of the butter until light. Separate the eggs. Beat the egg whites until foamy. Fold the egg yolks, egg whites, mace and breadcrumbs into the whisked butter and fill the crayfish head with this mixture. Form the remaining mixture into dumplings and cook these in boiling salt water for 5 minutes.

Put about 3½ ounces of the butter and the flour in a skillet over medium-low heat to make a roux, stirring constantly.  Add a little of the asparagus and cauliflower water, and whisk to make a thick sauce.

Brown the remainder of the butter over medium heat in a small pan, and set it aside.

Place the mixed vegetables, except the morels, into a serving bowl. Add some of the roux sauce, then the crayfish tails and dumplings, sprinkle with browned butter, and add the morels, crayfish legs and heads. Pour the sauce over it. Then add the dumplings and crayfish tails. Drizzle everything with brown butter, and arrange the morels, and crayfish heads and claws on top.

Nov 122017

On this date in 2014 the lander module Philae detached from the Rosetta space probe built by the European Space Agency and landed on comet Churyumov–Gerasimenko (a.k.a. 67P) at 15:33 UTC.

Rosetta was set to be launched on 12 January 2003 to rendezvous with the comet 46P/Wirtanen in 2011. This plan was abandoned after the failure of an Ariane 5 carrier rocket during Hot Bird 7’s launch on 11 December 2002, grounding it until the cause of the failure could be determined. In May 2003, a new plan was formed to target the comet 67P/Churyumov–Gerasimenko, with a revised launch date of 26 February 2004 and comet rendezvous in 2014. The larger mass and the resulting increased impact velocity made modification of the landing gear necessary.

After two scrubbed launch attempts, Rosetta was launched on 2 March 2004 at 07:17 UTC from the Guiana Space Centre in French Guiana. Aside from the changes made to launch time and target, the mission profile remained almost identical. Both co-discoverers of the comet, Klim Churyumov and Svetlana Gerasimenko, were present at the spaceport during the launch.

To achieve the required velocity to rendezvous with 67P, Rosetta used gravity assist maneuvers to accelerate throughout the inner Solar System. The comet’s orbit was known before Rosetta’s launch, from ground-based measurements, to an accuracy of approximately 100 km (62 mi). Information gathered by the onboard cameras beginning at a distance of 24 million kilometers (15,000,000 mi) were processed at ESA’s Operation Centre to refine the position of the comet in its orbit to a few kilometres.

On 25 February 2007, the craft was scheduled for a low-altitude flyby of Mars, to correct the trajectory. This was not without risk, as the estimated altitude of the flyby was a mere 250 kilometers (160 mi). During that encounter, the solar panels could not be used since the craft was in the planet’s shadow, where it would not receive any solar light for 15 minutes, causing a dangerous shortage of power. The craft was therefore put into standby mode, with no possibility to communicate, flying on batteries that were originally not designed for this task. This Mars maneuver was therefore nicknamed “The Billion Euro Gamble”. The flyby was successful, with Rosetta even returning detailed images of the surface and atmosphere of the planet, and the mission continued as planned.

The second Earth flyby was on 13 November 2007 at a distance of 5,700 km (3,500 mi).] In observations made on 7 and 8 November, Rosetta was briefly mistaken for a near-Earth asteroid about 20 m (66 ft) in diameter by an astronomer of the Catalina Sky Survey and was given the provisional designation 2007 VN84. Calculations showed that it would pass very close to Earth, which led to speculation that it could impact Earth.[73] However, astronomer Denis Denisenko recognized that the trajectory matched that of Rosetta, which the Minor Planet Center confirmed in an editorial release on 9 November.

The spacecraft performed a close flyby of asteroid 2867 Šteins on 5 September 2008. Its onboard cameras were used to fine-tune the trajectory, achieving a minimum separation of less than 800 km (500 mi). Onboard instruments measured the asteroid from 4 August to 10 September. Maximum relative speed between the two objects during the flyby was 8.6 km/s (19,000 mph; 31,000 km/h). Rosetta’s third and final flyby of Earth happened on 12 November 2009.

On 10 July 2010, Rosetta flew by 21 Lutetia, a large main-belt asteroid, at a minimum distance of 3,168±7.5 km (1,969±4.7 mi) at a velocity of 15 kilometers per second (9.3 mi/s). The flyby provided images of up to 60 meters (200 ft) per pixel resolution and covered about 50% of the surface, mostly in the northern hemisphere. The 462 images were obtained in 21 narrow- and broad-band filters extending from 0.24 to 1 μm. Lutetia was also observed by the visible–near-infrared imaging spectrometer VIRTIS, and measurements of the magnetic field and plasma environment were taken as well.

In May 2014, Rosetta began a series of eight burns. These reduced the relative velocity between the spacecraft and 67P from 775 m/s (2,540 ft/s) to 7.9 m/s (26 ft/s). In 2006, Rosetta suffered a leak in its reaction control system (RCS). The system, which consists of 24 bipropellant 10-newton thrusters, was responsible for fine tuning the trajectory of Rosetta throughout its journey. The RCS operated at a lower pressure than designed due to the leak. While this may have caused the propellants to mix incompletely and burn ‘dirtier’ and less efficiently, ESA engineers were confident that the spacecraft would have sufficient fuel reserves to allow for the successful completion of the mission.

Rosetta’s reaction wheels also showed higher than expected friction levels, though testing during the deep space hibernation period revealed the system could be operated safety at much slower speeds reducing the bearing friction noise. Before hibernation, two of the spacecraft’s four reaction wheels began exhibiting increased levels of “bearing friction noise” and one was turned off after the encounter with Lutetia to avoid possible failure. Engineers turned on all 4 wheels after the spacecraft awoke from Deep Space Hibernation in January 2014, ran them at lower speeds and elevated the control settings on the bearing heaters using an On-board Control Procedure to help reduce the level of bearing friction noise seen on 2 of the Reactions Wheels prior to Deep Space HIbernation. These changes allowed all 4 Reaction Wheels to be used throughout the period Rosetta was in orbit around 67P/Churyumov–Gerasimenko. Additionally, new software was uploaded which would allow Rosetta to function with only two active reaction wheels if necessary.

In August 2014, Rosetta made a rendezvous with the comet 67P/Churyumov–Gerasimenko and commenced a series of maneuvers that took it on two successive triangular paths, averaging 100 and 50 kilometers (62 and 31 mi) from the nucleus, whose segments are hyperbolic escape trajectories alternating with thruster burns. After closing to within about 30 km (19 mi) from the comet on 10 September, the spacecraft entered actual orbit about it.

The surface layout of 67P was unknown before Rosetta’s arrival. The orbiter mapped the comet in anticipation of detaching its lander. By 25 August 2014, five potential landing sites had been determined. On 15 September 2014, ESA announced Site J, named Agilkia in honour of Agilkia Island by an ESA public contest and located on the “head” of the comet, as the lander’s destination.

Philae detached from Rosetta on 12 November 2014 at 08:35 UTC, and approached 67P at a relative speed of about 1 m/s (3.6 km/h; 2.2 mph). It initially landed on 67P at 15:33 UTC, but bounced twice, coming to rest at 17:33 UTC. Confirmation of contact with 67P reached Earth at 16:03 UTC. On contact with the surface, two harpoons were to be fired into the comet to prevent the lander from bouncing off, as the comet’s escape velocity is only around 1 m/s (3.6 km/h; 2.2 mph). Analysis of telemetry indicated that the surface at the initial touchdown site is relatively soft, covered with a layer of granular material about 0.82 feet (0.25 meters) deep, and that the harpoons had not fired upon landing.

After landing on the comet, Philae had been scheduled to commence its science mission, which included:

Characterization of the nucleus

Determination of the chemical compounds present, including amino acid enantiomers

Study of comet activities and developments over time

After bouncing, Philae settled in the shadow of a cliff, canted at an angle of around 30 degrees. This made it unable to adequately collect solar power, and it lost contact with Rosetta when its batteries ran out after two days, well before much of the planned science objectives could be attempted. Contact was briefly and intermittently reestablished several months later at various times between 13 June and 9 July, before contact was lost once again. There was no communication afterwards, and the transmitter to communicate with Philae was switched off in July 2016 to reduce power consumption of the probe. The precise location of the lander was discovered in September 2016 when Rosetta came closer to the comet and took high-resolution pictures of its surface. Knowing its exact location provides information needed to put Philae’s two days of science into proper context.

Researchers expect the study of data gathered will continue for decades to come. One of the first discoveries was that the magnetic field of 67P oscillated at 40–50 millihertz. A German composer and sound designer created an artistic rendition from the measured data to make it audible. Although it is a natural phenomenon, it has been described as a “song” and has been compared to Continuum for harpsichord by György Ligeti. However, results from Philae’s landing show that the comet’s nucleus has no magnetic field, and that the field originally detected by Rosetta is likely caused by the solar wind.

The isotopic signature of water vapor from comet 67P, as determined by the Rosetta spacecraft, is substantially different from that found on Earth. That is, the ratio of deuterium to hydrogen in the water from the comet was determined to be three times that found for terrestrial water. This makes it very unlikely that water found on Earth came from comets such as comet 67P, according to the scientists. On 22 January 2015, NASA reported that, between June and August 2014, the rate at which water vapor was released by the comet increased up to tenfold.

On 2 June 2015, NASA reported that the ALICE spectrograph on Rosetta determined that electrons within 1 km (0.6 mi) above the comet nucleus — produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier — are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.

I don’t have any great ideas for food recipes to celebrate a module landing on a comet, but I do have two ideas for recipes in a wider sense. Once is a “recipe” for making a comet, or a simulacrum of a comet made out of common items, most of which are available in the kitchen. If you go on YouTube and search for “comet recipe” you will find any number of videos of people replicating the structure of comets using household items.  Here’s one:

That recipe does not produce something edible, however. On the other hand, there are quite a few recipes for cocktails called “comet.” They are all quite different from one another, and none, in my opinion, evokes comets in any way. I don’t drink alcohol any more, but when I did I had some memorable experiences with blackcurrant vodka, so this one struck a chord:

Comet Cocktail


30ml Smirnoff Double Black vodka
10ml blackcurrant cordial
60ml pineapple juice
lemon wedge


Shake the vodka, blackcurrant cordial, and pineapple juice in a cocktails shaker.  Pour over cracked ice in a glass and garnish with a lemon wedge.