Tag: satellite

In which I become… SPACE JUDGE

By Phil Plait | June 25, 2012 12:24 pm

Oh, I do love good news. A few days ago I wrote about a small group of aerospace experts who put up a Kickstarter project to launch a small satellite. The news? It’s fully funded! That means this satellite will get built and launched into space.

Be aware that, as with most Kickstarter projects, reaching their goal doesn’t mean you can’t or shouldn’t pitch in. More money pledged even after the goal is achieved means more and cooler stuff the project people can do with it!

And in this case, kicking in some cash gives you a chance to quite literally be a part of this mission: Discover Magazine is holding a contest where you can enter to get your experiment performed on this wee satellite. The details can be found here. Here’s the basic stuff:

(1) Fund the ArduSat project, for however much or little as you desire. You’ll receive a personal code that identifies you as a donor.

(2) Read the contest guidelines here to learn about how you should design and submit your idea.

(3) Enter with this entry form, making sure to include your personal code.

(4) Wait for winners to be announced on July 20th, after judging by Discover blogger Phil Plait, Discover Editor-in-Chief Corey Powell, and an expert panel of judges.

(5) Rejoice!

Note #4 there: I’m a judge! I’m pleased and honored to be asked to participate in this, and I’m very excited to see what folks come up with. I think this is an excellent project for a high school class or similar groups, and given it only costs a dollar minimum it’s well worth the effort.

Very important: the contest ends on July 6, 2012! So get moving. And maybe get your very own idea off the ground, and literally into space.

CATEGORIZED UNDER: About this blog, contest, Cool stuff, Space

Desktop Project Part 23: What are the odds of a satellite re-entering over water?

By Phil Plait | April 17, 2012 2:00 pm

[I'm approaching the Desktop Project endgame here; I'm almost out of pictures to post. I've done this every day for weeks, and my computer desktop is almost clean! Of course, more stuff keeps coming in, so I could do this forever. But that would be cheating. Sweet, sweet cheating.]

I’ve got something different for you today. Over the past few weeks I’ve posted an illustration, and a couple of dozen pictures, but no graphs! That’ll change now, and I think this particular set of plots is nifty.

Whenever a big satellite is about to re-enter Earth’s atmosphere — like UARS, or ROSAT, or Phobos-Grunt — the media freak out. You start seeing numbers being thrown about of the odds of getting hit by a chunk of flaming debris, and I get lots of panicked email and tweets. Then I have to point out to people that the Earth has a lot of real estate for a satellite to come down on, and of that, 3/4 is water. And most of that is Pacific Ocean. So really, the most likely scenario is a re-entry into the Pacific, or some other ocean, and that’s that.

But is that really true? After all, satellites can have different orbits, inclined with respect to the Earth’s equator. So the odds of getting dumped in the ocean might be different for a satellite that’s over the equator versus one in a polar orbit (that is, orbits almost completely in a north/south direction).

Happily, orbital debris specialist Mark Matney did the math! In a paper published in the Orbital Debris Quarterly Newsletter (bet you didn’t know that existed!) he calculated those odds. He created two graphs for the paper, and both are really cool if you’re a graph nerd like I am.
Here’s the first one:

That plot shows the fraction of the total area of the Earth covered by land versus latitude. It’s easy to read: at 0° latitude — the equator — the amount of land is 23%. In other words, if you flew a plane around the world at the equator, you’d be over land 23% of the time.

Read More

CATEGORIZED UNDER: Cool stuff, DeathfromtheSkies!, Space
MORE ABOUT: orbit, re-entry, satellite

UARS official re-entry… and up next: ROSAT

By Phil Plait | September 27, 2011 11:51 am

NASA has released the final update on the UARS bird that burned up in re-entry last week: it came down in the Pacific, west of the US.

The Earth’s atmosphere is not a lid over us, but gets thinner with height, so it’s hard to define exactly what it means to say that the satellite burned up at such-and-such a spot. However, at 04:01 UTC on September 24th, the satellite’s motion became dominated by the Earth’s atmosphere, and for all intents and purposes that can be called the point where it came back in… or at least, where it started. The forward motion of the satellite took the pieces along a track 500 – 1300 km (300 to 800 miles) long, which is still safely out in the ocean.

Thus ends the UARS tale.

… but we’re not quite done yet. The venerable German astronomical satellite ROSAT is due to come back down in about a month or so. Smaller than UARS — a little over 2 tons, as opposed to over 6 — ROSAT will probably have more pieces survive the ride down because its mirrors had to be shielded from heat to operate. That means the odds of it hitting someone will be slightly higher than from UARS, about 1 in 2000. Bear in mind that’s still really small odds! The chance of a specific individual getting hit are still something like only 1 in 14 trillion.

ROSAT is an X-ray satellite, designed to study high-energy radiation from astronomical sources. Years ago, I looked briefly at ROSAT data of a supernova remnant while putting together an educational activity about exploding stars. I don’t feel the same connection to the satellite as I do to, say, Hubble, but still, it’s a little sad to see it come down. However, it did provide years of outstanding service to the astronomical community, and gathered a vast amount of data about the high-energy Universe around us.

Image credits: NASA; German Aerospace Center (DLR)

CATEGORIZED UNDER: NASA, Space

UARS down over the Pacific ocean

By Phil Plait | September 24, 2011 9:02 am

NASA has confirmed that the Upper Atmosphere Research Satellites, UARS, burned up over the Pacific Ocean last night, September 24, between 03:23 and 04:09 a.m. UTC (11:23 p.m. and 12:09 Eastern US time). I have no other reliable information on it, but I expect we’ll get more updates soon. There were lots of reports last night of it falling over Canada, but those were mistakes or hoaxes. Apparently some people were fooled by meteors, Chinese lanterns, and possibly even the planet Jupiter. That’s happened before.

If I find photos or such I’ll try to post them, but I’ve heard no reports of witnesses, and I’ll be away this afternoon for my TEDxBoulder talk, so if any pictures turn up I may not be able to get to them. I imagine SpaceWeather will post any if they crop up.

Thus ends that saga. If you’re curious, you can read about the history of the UARS and what we learned from its 15 year mission to investigate our planet’s atmosphere.


Related posts:

- UARS update 5: new predicted re-entry tonight at 05:10 UTC +/- 2 hrs
- UARS update 3: new predicted re-entry tonight at 03:16 UTC +/- 5 hrs
- UARS update 2: new predicted re-entry at 00:58 UTC
- Update: satellite *might* fall on Friday at 22:00 UTC +/- 9 hours
- NASA satellite due to burn up some time in the next few days

CATEGORIZED UNDER: NASA, Space
MORE ABOUT: re-entry, satellite, UARS

UARS update 5: new predicted re-entry tonight at 05:10 UTC +/- 2 hrs

By Phil Plait | September 23, 2011 8:35 pm

The Center for Orbital and Reentry Debris Studies has updated their predicted re-entry time for NASA’s UARS satellite. It is now 9/24 (tonight!) at 05:10 UTC (01:10 Eastern US time), which puts it over the southern Indian ocean:

See Related posts below for information and background. Note the uncertainty is once again smaller, at +/- 2 hours!


Related posts:

-UARS update 3: new predicted re-entry tonight at 03:16 UTC +/- 5 hrs
- UARS update 2: new predicted re-entry at 00:58 UTC
- Update: satellite *might* fall on Friday at 22:00 UTC +/- 9 hours
- NASA satellite due to burn up some time in the next few days

CATEGORIZED UNDER: Cool stuff, NASA, Space
MORE ABOUT: re-entry, satellite, UARS

UARS update 3: new predicted re-entry tonight at 03:16 UTC +/- 5 hrs

By Phil Plait | September 23, 2011 11:07 am

[UPDATE to the update (22:00 UTC): a new prediction just came out: tonight, September 23/24, at 04:04 UTC (midnight Eastern US time). The uncertainty is down to +/- 3 hours, and the location is the middle of the Pacific. Clicking the links below to CORDS or the image itself will take you to the most current prediction.]

The Center for Orbital and Reentry Debris Studies has updated their predicted re-entry time for NASA’s UARS satellite. It is now 9/24 (tonight!) at 03:16 UTC, which puts it over the Sahara:

Note that again this is later than the last estimate. As the satellite has gotten lower, aerodynamic drag — the wind blowing on it, tenuous as it is — has changed its orientation, creating less drag, slowing the descent.

Please note that the time is still uncertain, though now it’s only +/- 5 hours. Still, that’s a wide swath of Earth in that range, so we’re still not sure where it’ll burn up.

Check the Related posts links below for more info on the satellite, why it’s coming down, and how to read that map. Again, the danger from this is pretty minimal. You may note that the three predictions we’ve had have put re-entry over the ocean or otherwise largely uninhabited areas, and that’s not a coincidence: most of the Earth is like that! That’s why the odds of someone getting hit are so low.

I’m sure we’ll get another update or two in the next few hours, so stay tuned. You can also check the CORDS site for updates, and the NASA page as well.


Related posts:

- UARS update 2: new predicted re-entry at 00:58 UTC
- Update: satellite *might* fall on Friday at 22:00 UTC +/- 9 hours
- NASA satellite due to burn up some time in the next few days

CATEGORIZED UNDER: Cool stuff, NASA, Space
MORE ABOUT: re-entry, satellite, UARS

UARS update 2: new predicted re-entry at 00:58 UTC

By Phil Plait | September 22, 2011 9:07 pm

The Center for Orbital and Reentry Debris Studies has updated their predicted re-entry time for NASA’s UARS satellite. It is now three hours later than before: 9/24 at 00:58 UTC, which puts it in the middle of the south Pacific:

Mind you, the uncertainty on this is still +/- 7 hours, so we’re a long way from knowing just where it will come down.

For more details, please read this earlier post (and you might as well read this one as well for the background info).


MORE ABOUT: re-entry, satellite, UARS

Update: satellite *might* fall on Friday at 22:00 UTC +/- 9 hours

By Phil Plait | September 22, 2011 11:40 am

NASA’s UARS satellite will almost certainly plunge back to Earth sometime Friday, September 23. The exact time is still not known, but the window for re-entry is centered at 22:00 UTC (6:00 p.m. Eastern US time) with a 9 hour uncertainty on either side. The Center for Orbital and Reentry Debris Studies puts the satellite off the west coast of South America at that time:

However, this is still very preliminary! In other words, if you live in that area, don’t panic (in fact, odds are you shouldn’t panic at all). The uncertainty is still pretty big, because it’s very difficult to pin down just when and where a satellite will come down. The +/- 9 hour window is a pretty clear indication of that. Atmospheric conditions play a big role, as does the fact that the satellite is tumbling; that means the amount of drag from our air that it feels as it orbits changes constantly, making the exact moment of re-entry too hard to determine this far out. As time goes on, it’ll get more precise.

The map shows several things. At the currently predicted re-entry time, the satellite is just west of Peru. The orange circle around it marks the area where re-entry would be visible. The blue track is the orbital position of the satellite over the Earth before the predicted re-entry, and the yellow after it; both are marked with tick marks at 5-minute intervals. The track moves across the Earth because the Earth is rotating under the satellite! That changes the apparent ground track. The white line marks the day-night boundary, so it’ll be late afternoon locally at the predicted re-entry location.

As of 07:00 Eastern US time, NASA was reporting UARS’s orbit being slightly elliptical at 185 x 195 km (115 x 120 miles). That’s very low, as you’d expect for a satellite about to come down. NASA has provided an RSS feed for updates if you want to stay on top of this, but I’ll note the CORDS site appears to be more current. They also have a nice discussion of how and why satellites come back down.

I’ll update this post as I hear news, but if there’s a significant change in the time or status, I’ll put up a new post.

CATEGORIZED UNDER: NASA
MORE ABOUT: satellite, UARS

NASA satellite due to burn up some time in the next few days

By Phil Plait | September 21, 2011 6:27 am

[UPDATE: Alan Boyle at Cosmic Log is reporting that the satellite will definitely come down on Friday, though NASA is not sure yet exactly when and where.]

[UPDATE 2: Emily Lakdawalla at The Planetary Society blog has lots of detailed info now.]

By now you’ve probably heard that NASA’s Upper Atmospheric Research Satellite (UARS, pronounced YOO-arz, though in my head it’s always "You arse!") will burn up in our atmosphere some time between Thursday and Saturday. The satellite was decommissioned in 2005 and they used the remaining fuel to lower the orbit. It’s been slowly getting lower since then, but recently reached the part of our air where it slows and drops dramatically. As you can see from this plot (click to embiggen), it’s dropped from about 375 km to 200 in just the last few months, and down it’ll come later this week.

No one knows where or when it will hit, since the final flight path will depend on changing atmospheric conditions, orientation of the satellite, and so on. Most of the 6 ton satellite will burn up, but some two dozen or so pieces are expected to survive re-entry.

Speaking of which: I’m seeing some concern over people getting hit by this thing. The odds of that are extremely low. It’s possible — NASA rates the odds at about 1 in 3200 — but highly unlikely. Mind you, those are the odds of anyone getting hit by debris. The odds of a specific person, say me, getting hit are far lower — if I’m doing this math correctly, you’d multiply that number by the population of the Earth, nearly seven billion people. So the odds of me (or you, or pick someone) specifically getting hit are about 1 in 20 trillion. Pretty long odds.

In the meantime, on September, 15th, "amateur" astronomer Thierry Legault was able to capture video of the satellite while it passed over his location:

Cool, eh? You can see the rotation; it’s tumbling, apparently. Out of power, it can’t keep the correct attitude, and over time something has caused it to spin. Maybe it was a collision, or maybe it’s from other subtle but persistent forces over the years (solar wind, light pressure, drag through our tenuous upper atmosphere, slow fuel leak, what have you). Here are some stills from Thierry’s video to make that more clear:

Pretty cool. So stay tuned. I’ll update with more info when I get it; we’ll know the re-entry time and location much better as the week progresses. <a href="I’ll be tweeting about it as well as soon as I find anything out.

Credits: Orbit plot: Jonathan McDowell; UARS images: Thierry LeGault.


Related posts:

- YouTube video where I explain a satellite re-entry
- BREAKING: SpySat successfully hit by missile
- The return of Stardust
- Spy sat to come home… not too secretly

CATEGORIZED UNDER: NASA, Space

Rename a NASA satellite

By Phil Plait | February 10, 2008 8:18 pm

The naming of names for astronomical satellites is a funny game. Most are weird acronyms (WFPC, STIS, NICMOS are all Hubble cameras), which many times are puns on the mission itself (FAST). Some are named simply, after astronomers who contributed to the field of study (Chandra, Spitzer). The Swift satellite is not an acronym or named after anyone. It’s just a swift satellite.

Right now, the Gamma-ray Large Area Space Telescope is very close to launch. But "GLAST" is not the best name. I worked on the education and public outreach for the mission for years, and sometimes the hardest part was using that name (though it made for some fun puns; I wrote articles like "The GLAST Resort"). Because of the picture we used a lot for GLAST, shown on the left, I called it the "flying cheese block".

It’s time to rename GLAST into something cool. And NASA wants you to help.

Got an idea for a new name for GLAST? Send it to NASA (through Sonoma State University)! There are some things you need to know, though. For example, it’s a gamma-ray observatory, so if you want to name it after some gamma ray pioneer, they can’t still be alive (that’s a NASA tradition). The name should be catchy, but not too silly (it’s a $350 million mission that’s managed by both NASA and the Department of Energy, so some modicum of decorum is necessary). It needs to be simple, and easy to say (so Mxyzpltlk is out, even if you try to say it backwards).

I actually don’t have too many ideas. Jan van Paradijs was a beloved astronomer who worked on gamma-ray astrophysics, but his name is too hard to spell for most Americans. Maybe some variation on it?

Please, no Mr. Spaceypants. It doesn’t matter anyway; this isn’t a vote or a contest, just a way to suggest cool names for the mission.

To get you started: GLAST will look at high-energy radiation from black holes, active galaxies, gamma-ray bursts, antimatter annihilation, and even from solar flares. If you go the acronym route, GR is not a bad combo for some good words (can we get GROK out of it? OGRE?). Gamma rays are Super High Energy, too. Also, it’s not a traditional telescope, either.

The deadline is March 31, 2008. So get thinking! Post your suggestions in the comments. Let’s see what we can come up with!

CATEGORIZED UNDER: Cool stuff, NASA
MORE ABOUT: GLAST, NASA, satellite
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