Interesting "asteroid" 2010 AL30 close approach. Poss Rocket

[deanrobertson]

If this has an orbit of approx one year, it wouldn't be making a closer approach to earth on or around Dec. 20, 2012? Just asking, not worried.

 

[MeteorWayne]

No it doesn't come any closer than 75 times lunar distance until 2013. (remember, this pass was 0.3 lunar distance)

If you look at the sbdb page for the asteroid I linked to above, at the bottom the close approaches are listed. 1 lunar distance is about0.0026 AU (the distances are listed in AU)

MW

 

[optronics48]

MeteorWayne, this is off topic but....I was looking through my 6 in f6 reflector at 40x following a satelite. Suddenly, another satellite going at 90 degrees to the first one crossed my view..for an instant I saw both sats at the same time crossing each others paths...I swung around the scope and was able to follow this second sat for a while...I know they must have had different orbits...
I wondered if this was a common ocurrence or was I very lucky to have witnessed an unusual event ?

 

[MeteorWayne]

Interesting. Well, since you didn't plan it, probably pretty lucky, I'd say How common is it? I really don't know. Of course using a scope, you can see many more faint satellites than you can by eye, so that increases your odds quite a bit. My satellite observing is rather casual (except for the ISS, Iridiums, and nights when I'm entartaining the public), just what I happen to notice when I am meteor observing, so I'm no expert. I'd say keep track of how often it happens!
MW

 

[csmyth3025]

Thanks Solifugae for your detailed analysis of a hypothetical impact of an object of this size. As a layman I was surprised by both the minimal effects such an impact would have and by the statistical frequency of encounters of this type.
According to Wikipedia "...the Himalayan system includes over 100 mountains exceeding 7,200 m (23,622 ft)..." I suppose if you were a very unlucky mountain climber making his final ascent on one of these peaks and this hypothetical impact targeted the summit of the mountain you were attempting to climb, a 160 kiloton air burst would pretty much ruin your day.

Chris

If, for the sake of argument, it turns out to be a nickle-iron asteroid, what sort of crater (on land) might it produce?

I'm not sure of the asteroid's speed, but assuming a typical 17km/s and other typical specifics (such as impact angle), your hypothetical gets this:

Distance from Impact: 1.00 km = 0.62 miles
Projectile Diameter: 11.00 m = 36.08 ft = 0.01 miles
Projectile Density: 8000 kg/m3
Impact Velocity: 17.00 km/s = 10.56 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock

Energy before atmospheric entry: 8.06 x 1014 Joules = 192.46 KiloTons TNT
The average interval between impacts of this size somewhere on Earth is 30.9 years

The projectile begins to breakup at an altitude of 13700 meters = 44800 ft
The projectile bursts into a cloud of fragments at an altitude of 7180 meters = 23500 ft
The residual velocity of the projectile fragments after the burst is 7.28 km/s = 4.52 miles/s
The energy of the airburst is 6.58 x 1014 Joules = 0.16 x 10^0 MegaTons.
Large fragments strike the surface and may create a crater strewn field. A more careful treatment of atmospheric entry is required to accurately estimate the size-frequency distribution of meteoroid fragments and predict the number and size of craters formed.

So the result is a 160 Kiloton airburst at just over 7km. Airblast is not noticeable (The overpressure is less than 1 Pa)

Using porous rock instead of iron, it bursts at 36.4km with 140 Kilotons of energy. Neither scenario is dangerous, and if I remember correctly, last year, an asteroid of similar size exploded over Indonesia. It would be more of a scientific interest than a danger, even if iron.

The initial estimate included the possibility that it was 25m. An iron asteroid of this size is tended to where it can strike the ground and create a significant crater.

 

[MeteorWayne]

He used this site:

http://www.lpl.arizona.edu/impacteffects/

You can play around with different types of objects, different distances from the impact, different target rock, velocity and impact angles, etc.

It's pretty interesting to experiment with the changes using different parameters.

 

[MeteorWayne]

Wow, 268 observations reported over a 3 day arc. I don't think there will be too many more, since the object is now between us and the sun, and by the time it emerges from the sun side it will be too faint to track. I'll check the ephemeris to find out when that will be, best guess is sometime in late March

From what I can tell, this object now has more optical observations than ANY other on the JPL Sentry Risk List except for Apophis (which has a 4 year arc) and 1999 RQ36, which has a 7 year arc...

 

[Woggles]

Here an article from Discovery News http://news.discovery.com/space/could-a ... ocket.html.

"Michael Khan did the math and back-tracked 2010 AL30's path through the solar system and believes that the object's life began with the launch of the ESA Venus Express mission in 2005."

Also the author talks about the NASA's Goldstone Solar System Radar is doing work on this as well

 

[Woggles]

In this article is a link to a movie made of 2010 AL30.

http://www.deseretnews.com/blog/47/1000 ... stery.html

 

[MeteorWayne]

Here's a direct link to the movie; it moves horizontally from left to right. I seem to see some brightness variations.

http://users.wirelessbeehive.com/~paw/t ... AL75.2.GIF

 

[bushwhacker]

Nice, that thing was moving right along too. Thanks Wayne

 

[MeteorWayne]

Now 275 visual obs, and 2 radar doppler measurements! Amazing, for such a tiny little piece of flotsam!!

 

[wkitty42]

MeteorWayne, this is off topic but....I was looking through my 6 in f6 reflector at 40x following a satelite. Suddenly, another satellite going at 90 degrees to the first one crossed my view..for an instant I saw both sats at the same time crossing each others paths...I swung around the scope and was able to follow this second sat for a while...I know they must have had different orbits...
I wondered if this was a common ocurrence or was I very lucky to have witnessed an unusual event ?

i see this quite often when i'm out doing eyeball satellite observing... i also see a north bound one being passed by a southbound one at about two fingers (at arm's length) separation... we are always lookin' up around here... especially since we're at least 15 - 20 miles from everything and have fairly dark skys...

 

[Woggles]

Hi MeteorWayne

I was just wondering if any one has figure out what it was? I can't seem to find anything stating one way or another if it was asteroid or space junk?

Thanks

 

[MeteorWayne]

I've been looking as well, and haven't found any definitive statements either. Rest assured, I'm continuing to look

BTW, now 300 optical observations over the 3 day arc.

 

[bushwhacker]

Interesting seems to be the operative word on this thing. I remember when this discussion started you(MW) stated that for this object to have gotten so many observations was almost unheard of...
So what are they seeing that keeps them so busy?

 

[MeteorWayne]

Well, it's not really busy....the observations, though trickling in, all were taken during the same 3 days near close approach (it moved to the sun side afterward).

I think it was just curiousity above all else, but that's just a guess. It was a pretty close approach, but as I stated back in the beginning, a period so close to exactly one year made it uniquely interesting. (Hmmm, good question Wayne, I wonder how many other asteroids have periods that close).

BTW, the latest data on the period, now with teeny weeny error bars is
366.0918602451769 +/- (1 sigma) 0.0002391 days, about 0.2% longer than an earth year.

a (semimajor axis) = 1.001523391948332 =/-4.3607e-07 AU

Earth MOID = 3.79391E-5 AU ...it's really amazing that with this distance it's not on the risk page, except that with a period only 0.2% longer than earth's it will be ~ 433 years until it comes around that close again . Except (again) it has close approaches to Venus and Mars that may significantly change the orbit over century long time scales.

 

[MeteorWayne]

I did quick search through an asteroid database through 2006 (I couldn't find a more current one, probably because of the huge number of discoveries in the last 3 years) and at that time there were exactly 7 asteroids with a semimajor axis between 0.998 and 1.002 AU (remember 2010 AL30 is 1.001523391948332 AU). (Edit 2: there were 25 with a between 0.98 and 1.02) So asteroids with orbital periods this close to 1 year are extremely rare, considering there are at least half a million known....

At the time, there were about 140,000 numbered asteroids, and several hundred thousand known ones awaiting numbers.

(BTW, as of Dec 31, 2009, there are 229,914 numbered asteroids, and 142,711 that have multiple opposition observations awaiting numbering. Another ~ 278,000 have only obs at a single opposition.

 

[csmyth3025]

I know this question is going to make me sound really uninformed - but I'll ask it anyway.
Except for the fact that asteroids with an orbital period that closely match that of the earth are rare, is this coincidence significant in telling us anything about the history of the object? Or is it just a statistical anomaly - sort of like rolling "snake eyes" three times in a row?

Chris

 

[MeteorWayne]

It's a good question. What it tells us is that the orbits could be related because they have almost exactly the same energy. The total amount of orbital energy determines the semimajor axis and the period. So a 1 year circular orbit can be converted to a 1 year elliptical orbit with some well timed pushes and pulls. In fact the earth's orbit becomes more and less elliptical over millions of years, but the period remains 365.25 days because the total energy doesn't change.

So it shows, in a way, that it could be an earth derived spacecraft, because such an object would have started out in a 365.25 day orbit. Since a rocket accelerates away from the earth, it would have changed some, requiring something like the scenario calculated in the link a few pages back...a very nice analysis.

http://www.scilogs.eu/en/blog/go-for-la ... r-tomorrow

So far nothing has been proven, of course, it's just, ummm, interesting

 

[csmyth3025]

Meteor Wayne,
Your link is an excellent explanation of how this sort of thing is investigated and analyzed. In the end it appears that the author considers it a distinct possibility that the Cosmos rolled the dice and came up with "snake-eyes" three times in a row.

Chris

 

[MeteorWayne]

Yes, his latest update does show that.

 

[MeteorWayne]

I stumbled across another interesting one. 2009 BD has 121 observations over a very long arc (289 days), a nearly circular orbit with a period just a touch over 1 year (370 days) and has a 9.1 LD close approach on May 7th. It's very small 6-13 meters.

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2 ... ;cad=1#cad

It has a much closer approach (< 1 LD, 0.0023 AU) next June 2nd (Both Sentry and NEODyS).

It's actually way down on the JPL Sentry risk page with 7 virtual impactors between 2071 and 2093 (Cumulative PS -7.14, highest risk 2078 PS - 7.54)

On NEODyS the 2078 event is PS -7.18, 5 VI's between 2071 and 2090 (When their automated search ends)

 

[csmyth3025]

Out of curiosity, I was wondering if it's likely that an object the size of the one that caused the "Tunguska Event" would not be detected prior to its imminent impacting approach. The Wikipedia article on this object describes it (in part) as follows:

"Although the cause of the explosion is the subject of debate, it is commonly believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3.1–6.2 mi) above the Earth's surface. Different studies have yielded varying estimates of the object's size, with general agreement that it was a few tens of metres across.[4]"

Is it more likely that a pre-impact sighting (made today) would yield a projected orbit that could provide an estimate of a future impact? Is such a pre-impact sighting a matter of just "getting lucky"?

Chris

 

[MeteorWayne]

Well, depending on which direction it came from, it is probable that we would have "some" warning for an object in that "tens of meters" size class.

For example, Asteroid, Size, Lead time to Close approach from the last week.

2010 AF40, 26-59m, 9 days
2010 AN61, 10-23m, 4 days
2010 AG3, 8-19m, 11 days

So we do detect objects in this size range in advance some of the time.

There is always a risk of one out of the plane of the ecliptic, or coming out of the sun's direction, sneaking in with little or no warning.

When PanStarrs comes online, the risk from out of plane asteroids will decrease some. But there will always be a risk. In fact, that's what the Palermo Scale is, it's an estimate of risk for an asteroid we know about compared to the ones we don't.