Good morning from Boston. The CZ-5B Y3 rocket stage is approaching reentry; new Aerospace Corp and US Space Force estimates narrow the reentry window to two hours and @Marco_Langbroek's estimate overlaps but is slightly longer.
@Marco_Langbroek I am going to use the @AerospaceCorp estimate for now, which predicts reentry between 1615 and 1815 UTC. This reentry window opens in three hours from now.
@Marco_Langbroek@AerospaceCorp Here is the updated decay plot showing the narrow predicted reentry windows (the @EU_SST one has not been updated since yesterday)
@Marco_Langbroek@AerospaceCorp@EU_SST With this narrower reentry window we can really start to say something about where it might come down. Let's go through the ground track during the reentry window.
@Marco_Langbroek@AerospaceCorp@EU_SST As the window opens around 1615 UTC the rocket stage is heading southeast over Brazil and then over the Atlantic Ocean to a point south of Cape Town
@Marco_Langbroek@AerospaceCorp@EU_SST From 1630 to 1650 UTC the rocket stage orbits over the Indian Ocean, reaching Sumatra at 1650 UTC and Borneo at 1653 UTC
@Marco_Langbroek@AerospaceCorp@EU_SST After passing over Naga in the Phillipines at 1656 UTC, the stage heads over the Pacific Ocean, taking half an hour to cross that huge expanse
@Marco_Langbroek@AerospaceCorp@EU_SST The path grazes Baja California at 1726 UTC, Jalisco (Mexico) at 1728 UTC, passes over Guayaquil, Ecuador at 1736 UTC, northern Peru, Santa Cruz in Bolivia (1742 UC), Paraguay, Parana in Brazil, before heading out over the Atlantic again at 1746 UTC
@Marco_Langbroek@AerospaceCorp@EU_SST Finally it passes S of S Africa again at 1753 UTC and then back out over the Indian Ocean at the close of the window.
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The public are excited by the images, but astronomers are as excited by the spectra, like this one. I want to talk about why
The data are the white wiggly line which show the amout of light at each precise color. There are particular spikes where there's more lightm for example the one marked 'hydrogen' at 4.61 or so.
The presence of four such spikes ("spectral lines") in a very precise pattern is a fingerprint of the element hydrogen. We know that light must have been produced by hydrogen atoms. The spacing of the four lines marked in blue is also distinctiive and is a fingerprint of oxygen
Slightly better res version showing the lensing arcs clearly
We're looking at a cluster of galaxies 5 billion light years away, and images of even more distant galaxies behind it that are distorted and magnified by the gravity of the cluster
Here is a Hubble image of the same object, SMACS J0723.3-7327.
Hard to see the improvement that JWST gives on the screencap from the brieifing, but it will be significant
The correct name for the first object in this list is SMACS J0723.3-7327. It's a cluster of galaxies at a redshift of z=0.39 in the southern constellation Volans and was discovered in 2011 by the Planck survey as PLCKESZ G284.99-23.70 (lots of objects have multiple names, alas)
WASP-96b is a planet orbiting the 12th magnitude G8 star 2MASS 00041112-4721382, in the constellation Phoenicis
Phew, finally done with meetings for the day.
To recap: Webb targets SMACS J0723.3-7327, 5 gigayears away in Volans;. WASP 96b, star in Phoenix (not Phoenicis, oops).
Also Southern Ring Nebula is NGC 3132, a planetary nebula in the constellation Vela about 2000
light years away.
Some statistics on the topical subject of uncontrolled reentries of rocket stages, from my database.
I assume that stages with dry masses less than 1500 kg ("small stages") burn up completely on reentry, and more massive ones ("big stages") may have bits that hit the ground
So I will focus on big stages that made uncontrolled reentries. These can happen from 12 hour after launch to many years after launch (active or targeted reentries always happen at less than 12 hours).
Since Jan 1992 (past 30.5 yers) there have been 860 uncontrolled reentries of large rocket stages, so about 28 per year. (Last 10.5 years only, figure is 25 per year).
The Axiom-1 mission jettisoned Dragon's trunk just prior to their deorbit burn on Apr 25. After three weeks in orbit the trunk reentered at 0902 UTC May 14.
Meanwhile Sandia Labs' MTI (Multispectral Thermal Imager) satellite, launched in Mar 2000, reentered at 0115 UTC May 14. The satellite was still operating in 2013 but I'm not sure when it lasted until; perhaps @SandiaLabs can tell us
@SandiaLabs Space-Track reports the reentry location of MTI (2610/2000-014A) as being 135E 79N over the Laptev Sea. Strangely it reports the Axiom trunk reentry location to be exactly the same - not possible given the trunk's orbit. I suspect a typo.