At 17:11 UTC, the very time of this posting, the December solstice occurred.
The word solstice comes from mid-13c., from Old French solstice (13c.), from Latin solstitium “point at which the sun seems to stand still,” especially the summer solstice, from sol “sun” (see sol) + past participle stem of sistere “to come to a stop, make stand still” (see assist(v.)).
One mis-conception about the December solstice (same for the June Solstice) is it occurs on the same day. While most of the time the winter solstice does fall on 21 December, depending on the moon the date can change a little.
With this launch ESA has advanced the potential for a huge leap forward in astronomical science.
No not over-stated at all. The “potential” will be realized when Gaia starts operation and gathering science data. Exciting stuff, this has been a LONG time coming.
All about Gaia from ESA:
ESA’s Gaia mission blasted off this morning on a Soyuz rocket from Europe’s Spaceport in Kourou, French Guiana, on its exciting mission to study a billion suns.
Gaia is destined to create the most accurate map yet of the Milky Way. By making accurate measurements of the positions and motions of 1% of the total population of roughly 100 billion stars, it will answer questions about the origin and evolution of our home Galaxy.
The Soyuz launcher, operated by Arianespace, lifted off at 09:12 GMT (10:12 CET). About ten minutes later, after separation of the first three stages, the Fregat upper stage ignited, delivering Gaia into a temporary parking orbit at an altitude of 175 km.
A second firing of the Fregat 11 minutes later took Gaia into its transfer orbit, followed by separation from the upper stage 42 minutes after liftoff. Ground telemetry and attitude control were established by controllers at ESA’s operations centre in Darmstadt, Germany, and the spacecraft began activating its systems. Continue reading →
The Antares was raised upright in anticipation of a launch later today, 19-Dec. However due to the cooling control valve problem on the space station the launch was postponed until mid-January.
We sort of knew the delay was coming, so it’s not a big surprise. As for the cooling valve, the fix will be accomplished by a series of spacewalks by (NASA) astronauts Rick Mastracchio and Mike Hopkins to replace the pump module.
The spacewalks will occur on December 21, 23 and 25. The replacement pump module is one they have “on the shelf” on the external stowage platform. The offending control valve is mounted on this pump module in case you were wondering.
I hope to be watching as coverage is going to be on NASA-TV and a link here if one is available and usually NASA is very good about such things. I am very interested in how the pump module is interfaced, always open to new ideas you see. The spacewalks are going to take six and a half hours EACH. Wow! Hope the suits work well and there is not water in the helmet issues. TV coverage (and hence the linked video) will begin at 06:15 EST / 11:15 UTC.
As for the raised Antares rocket, they will lower it and put it in “storage” out of the elements.
RS Puppis is a Cepheid variable star. Thanks to the work of Henrietta Leavitt at Harvard, we know there is a relationship between the period of variability and the luminosity (intrinsic brightness) of a Cepheid variable. This means we can use Cepheid as a standard candle to as one way to determine distance to the really far out star or galaxy the stars reside in.
Distances to closer objects can be determined by other means like the parallax but that tends to be less accurate at great distances. One of the reasons the ESA Gaia launch is so exciting is that parallax measurements will be very accurate and to greater distances than we can do currently. Distances to the stars are very difficult to get accurately.
From NASA (links to a full res image and it is amazing!) with acknowledgment to H. Bond (STScI and Pennsylvania State University):
This festive NASA Hubble Space Telescope image resembles a holiday wreath made of sparkling lights. The bright southern hemisphere star RS Puppis, at the center of the image, is swaddled in a gossamer cocoon of reflective dust illuminated by the glittering star. The super star is ten times more massive than our sun and 200 times larger.
As the NASA caption below explains this is composite image of the Crab Nebula from Hubble and Herschel. ESA has a nice explanation of the Herschel data along with links to an image and a portion of spectrum. Active Argon? Cool stuff!
From NASA (larger versions of the image available here):
This image shows a composite view of the Crab nebula, an iconic supernova remnant in our Milky Way galaxy, as viewed by the Herschel Space Observatory and the Hubble Space Telescope. Herschel is a European Space Agency (ESA) mission with important NASA contributions, and Hubble is a NASA mission with important ESA contributions.
A wispy and filamentary cloud of gas and dust, the Crab nebula is the remnant of a supernova explosion that was observed by Chinese astronomers in the year 1054.
Late word has it the launch of Orbital’s Cygnus resupply spacecraft is being delayed due to the cooling problem in the ISS.
Orbital was to launch Cygnus on Tuesday (17-Dec) now are looking at launching no earlier than Thursday (19-Dec) to give ISS experts more time to look at the the problem flow-control valve in the ISS cooling system. Currently engineers are trying to stabilize the cooling loop using another valve to help regulate temperatures in a steady fashion. To that end the engineers are operating a Radiator Return Valve, putting it in various position and checking the results. This is a perfectly reasonable approach and although the precision of control would suffer, it could work just fine in a pinch; in the meantime cooling is provided by Cooling Loop B.
The “second-valve” approach would probably not be something they would want to count on in the long run so repairs are still being evaluated and space suits are being checked for leaks in case the crew are needed to conduct a spacewalk to replace the faulty pump module.
The possibility of the Cygnus launch being delayed until after the first of the year is not at all out of the question.
Saturn’s moons create art on the canvas of Saturn’s rings with gravity as their tool. Here Prometheus is seen sculpting the F ring while Daphnis (too small to discern in this image) raises waves on the edges of the Keeler gap.
Prometheus (53 miles, or 86 kilometers across) is just above image center while Daphnis (5 miles, or 8 kilometers across), although too small to see in its location in the Keeler gap just to the right of center, can be located by the waves it creates on the edges of the gap.
The Geminids meteor shower is upon us; perhaps you’ve seen a few already. The peak of the shower is the 13th and 14th and I would like to suggest you look before dawn on Saturday.
The radiant of the shower, that area where the meteors seem to emanate from, is not surprisingly the constellation of Gemini. The above image is a finders map for the northern hemisphere and if you click it you will get one for the southern hemisphere, both come from Gary Kronk’s excellent site: Meteor Showers Online.
The meteor rate can be anywhere between 50 and 100 meteors an hour and normally would provide a nice show. This year we have a moon that will be nearly full (~91%) and the brightness could limit visibility. Still it’s worth a look, I’m for sure going to be out there. I think I should have a pretty good sky to look at despite an approaching storm system. I would guess anyways, temps are supposed to be in the range of minus 15 to minus 20 degrees C so skies should be clear.
There’s a bit of a problem on the ISS involving a cooling pump system. Sounds like from the latest update below (as of this morning) it could be a valve issue. Mission control people are diagnosing the problem.
We should hear later today if the “fix” will involve a spacewalk in the immediate future. If the repair cannot be made with a spacewalk a replacement may be necessary. I don’t know if they have a spare on the shelf, and they could have, or whether a replacement will be need to be flown up.
The ISS will be getting a resupply flight from a Orbital 1 Commercial Resupply Services flight scheduled to launch on 18 December. Will the mission change to include a replacement pump if necessary if that is possible?
We will find out shortly.
This from the NASA website:
Earlier Wednesday, the pump module on one of the space station’s two external cooling loops automatically shut down when it reached pre-set temperature limits. These loops circulate ammonia outside the station to keep both internal and external equipment cool. The flight control teams worked to get the cooling loop back up and running, and they suspect a flow control valve actually inside the pump module itself might not be functioning correctly.
At no time was the crew or the station itself in any danger, but the ground teams did work to move certain electrical systems over to the second loop. Some non-critical systems have been powered down inside the Harmony node, the Kibo laboratory and the Columbus laboratory while the teams work to figure out what caused the valve to not function correctly and how to fix it. The crew is safe and preparing to begin a normal sleep shift while experts on the ground collect more data and consider what troubleshooting activities may be necessary.