Wednesday, March 18, 2020

Système Solaire

A planet by any other name... Have you ever had a burning desire to know the names of all the planets in the Welsh language? I, for one, was afire with curiosity. Wonder no further: 

 English / Cymraeg 
= Mercher
= Gwener
= Daear
= Mawrth
= Iau
= Sadwrn
= Wranws
= Neifion
= Plwton 

And now you know where J.R.R. Tolkien got his inspiration for the territories around Hobbiton. 

Nine Planets by Bill Arnett Renaissance techie Bill Arnett runs a delightful web site called NINE PLANETS, and for awhile he inserted a graffiti-esque "8" to observe the demotion of Pluto. More recently, he added the subtitle "We still love you, Pluto!" and all his information about the original nine remains intact. 

One of his most fascinating and well-researched appendices, in my opinion, is the Planetary Linguistics

I'm partial to the tongue of the Cymry as it is one part of my personal heritage, but this appendix lists popular, transitional, and dead languages -- from Sumerian to Latin to Olde English to Icelandic to Farsi to French. He also demonstrated how some of these terms evolved into the months of the year, and days of the week... Saturni... Saturn's Day... Saturday

 I had a splendid time going through all of these, and also googling some of the less obvious words that weren't related to Latin roots, only to find that many were separate names of deities, specific to the cultures in question. The best days are when I learn something new! I also love how he added the fictional Klingon jargon toward the end. Again, Pluto has not been removed (though it seems people aren't in any tearing hurry to add Eris, Haumea or Makemake. Maybe soon!) 

 And for those of you uninterested in the random etymology of floating rocks 0.00000102529 or more light-years away, well... sorry. I do this sort of thing when I get bored. I was in Wales this time last year, and I'm feeling that hiraeth. If it makes you feel any better, the rest of the week will be spent watching SpaceX news...!

Monday, March 2, 2020

GEO LEO Death by Acronym

This will likely be the single most depressing addition to my SPACE TRIVIA series, but it's important to know. If you easily lose your Zen to not-happy space news, skip me and go read The Bad Astronomer today instead. Awesome blog.
But, here are some bite-sized facts about space junk. At this time, pieces of orbital debris in Low Earth Orbit (LEO) and Geosynchronous Orbit (GSO) number in the tens of millions.

That's right, tens of millions. Nearly 20,000 of these are larger than 10cm. Particles between 1-10cm are estimated at about half a million. The rest are less than 1cm.

Orbital Debris in Low Earth Orbit

Orbital Debris is defined as a human-made object in orbit around the Earth which no longer serves a useful purpose, such as launch vehicle upper stages, spent payload carriers, derelict spacecraft, pieces resulting from explosions or collisions, and even tiny paint flecks released by impacts.

Most orbital debris reside within 2,000 km of the Earth's surface, or are in LEO.

How do we estimate the numbers and placements? Ground-based radars can detect objects as small as 3mm, and space-based detection systems can detect things as far as 40,000km out.

The US Space Surveillance Network tracks all orbital debris larger than 10cm. An average of one catalogued piece of debris falls back to Earth each day, and this has been the case for the past four decades.

Orbital Debris in Geosynchronous Orbit

In LEO and below, orbital debris circles at around 7-8 kilometers per second, or up to 18,000mph.

As a result, the International Space Station (ISS) is the most heavily shielded spacecraft ever flown. Nodes holding human crews and pressure tanks on the structure are able to withstand impact of debris as large as 1cm. The ISS can also maneuver to avoid tracked objects.

The higher the altitude, the longer the debris will remain in orbit. Debris left below 600km fall back to Earth within a few years, though precious little survives the super-heated re-entry through Earth's atmosphere. Things higher than 800km take decades to return. Above 1,000km or more? Those may circle for a century or more.

Geosynchronous Orbit as seen from Polar View
GSO Polar View

Most telecommunications and meteorological satellites operate at the 36,000km altitude in geostationary orbit, where the problem or orbital debris is less severe. Which is not to say... harmless.

If you participated in the UARS hype, and have nothing better to be indignant about this week, you can read all about how NASA handles Orbital Debris Re-Entry. Or if you want to be part of all future re-entry hype, you can sign up for NASA's "Orbital Debris Quarterly" newsletter.