Should go back to co-hosting Games Master.
Asteroid-apocalypse experts were struck by a shower of eggs last week, as they prepared to sound the alarm over an incoming space boulder potentially capable of wiping out life on Earth - only to find that the object was a well-known European space probe on a planned flyby. The Minor Planet Centre (MPC) - which is to asteroids …
I can understand that ppl would be upset by a lack of information sharing, but it smacks of face saving really.
Ok, they might not know that the object is man made and intended to come by that close, but surely they can tell how big it is?! I'm guessing it ain't the size of Indo China and so we can all breathe easy. In fact if it were to smack right into us I reckon the headlines would be more along the lines of "ESA blows up *another* satellite" rather than "OMG we're all gonna dieeeeeeeeeee!".
Surely the real story here is that some boffins can shoot a satellite a few million (?) miles out and miss the planet by less than half its width! I'd love to know the (Paris Hilton) angle on that one.
OK so it's a good laugh and certainly an 'egg on face' moment for the MPC, but on the other hand:
(a) it's difficult to estimate sizes for these objects. All you've really got to go by is the brightness, so a shiny spacecraft a few metres across could be misinterpreted as a dull space boulder tens of metres across. If it entered the atmosphere, such an object might well cause a Tunguska-sized explosion - not a dinosaur killer, but definitely enough to ruin your day if you were underneath it.
(b) I find it reassuring that we're able to detect such small objects that have the potential for significant damage.
Actually, with the resolution of the optics used, they have a pretty good idea of the size and albedo (brightness) of the objects they're tracking. It's just in this case, the object unintentionally fit the parameters of an asteroid:
"The main spacecraft measures 2.8 x 2.1 x 2.0 metres, on which all subsystems and payload equipment are mounted. There are two 14-metre solar panels with a total area of 64 square metres. At launch, the vehicle weighs approximately 3000 kilograms (fully fuelled) including 1670 kilograms of propellant, 165 kilograms of scientific payload for the orbiter, and 100 kilograms for the lander."*
So that gives a width of about 30 metres, plus the solar panels had "Hundreds of thousands of specially developed non-reflective silicon cells"* which gave it a low albedo profile.
So a 30 metre, low albedo object streaking at high speed toward a near Earth fly-by. Not actually Earth shattering, but if it was an asteroid that size instead of a controlled probe, you definitely wouldn't want to chance it impacting the Earth.
*Quotes taken from http://www.esa.int/esaSC/120389_index_0_m.html
Astronomy is based on a bunch of whacky assumptions - like "brighter==bigger" from which roaring extrapolations are made. This cock up just goes to show how silly and unscientific many of those assumtions are.
As for being able to detect tiny things... well they only seem to be able to do that when approached from certain angles and at the right speeds. Five years back http://www.newscientist.com/article/dn2444.html happened. It was only detected **after** it had flown past. It was coming from the wrong angle and too fast.
They should consider subscribing to spacenews.com.
They send out nice weekly and even daily bits about what is going on in the sky, including Rosetta flybys, launches of landers to Mars, comets lighting up explosively, and all sorts of things one wouldn't want to confuse with *an incoming space rock!*.
As has been said, Tunguska didn't hit. But neither was it likely a comet, rather a lump of asteroid belt, so PH's statement is sound.
Sad to see the old fella maligned so much. Sure, he is getting somewhat past it, but what an incredible man in his day and how he advanced space and astronomy to the masses,especially during the days of 1, 2 and 3 TV channels only.
Life is wierd and I had the chance to bump into him on 3 occasions. The first was a guest lecture at QMC in '77. He spoke for an hour with no notes, at breakneck speed and totally coherently, the only piece of paper used was a tiny scrap which listed his slideshow - brilliant. The second was on the tube from Heathrow to central London in about '79. At first we were the only ones in the carriage, so I sat and talked with him, as you can imagine, he talked back - profusely. By Picadilly circus the carriage was crowded, people standing, staring in bewilderment at this unexpected scene. By then he was showing me slides of Venus just in from a russian lander. The third at an astro fair/event in about '90 where we had a passing acknowledgement and recall of previous meetings.
PH is ok by me, and I'm sure that any tiny quote from a jostling reporter cannot be indicative of his real opinions on the matter, he is much more likely to be sceptical of such things.
[perhaps we can have a comet or astroid icon? ;-)]
TITLE=(Fwd) MPEC V69: 2007 VN84 [a=1.19,e=0.34,i=1.9,H=26.3] [28805-]
Date sent: Thu, 08 Nov 2007 19:06:04 -0500 (EST)
Snip a bunch of observation stuff
2007 VN84 Earth MOID = 0.0001 AU
Epoch 2007 Oct. 27.0 TT = JDT 2454400.5 MPC
M 302.66563 (2000.0) P Q
n 0.76181070 Peri. 79.69236 -0.65353221 -0.75645089
a 1.1873297 Node 51.14851 +0.68070296 -0.60243373
e 0.3412776 Incl. 1.91562 +0.33096698 -0.25466771
P 1.29 H 26.3 G 0.15 U 9
(Snip the observations and such of which there are many)
The minimum distance from the geocenter is 0.000081 AU (1.89 Earth radii)
on Nov 13.844 UT.This object passes 5000 km from Earth's surface on Nov. 13 at 20 hours UT (Nov.
14 at 9 a.m. NZDT). From the H magnitude its diameter is in the 10-35 metres
There may be some news media interest. Note that the prediction is based on
only 1.6 days of observation.
Many hours of telescope and observer time was waisted because the
European Space Agency did not communicate with the minor planet center.
<< Sad to see the old fella maligned so much. Sure, he is getting somewhat past it, but what an incredible man in his day and how he advanced space and astronomy to the masses,especially during the days of 1, 2 and 3 TV channels only. >>
Agreed. He's a great man and a great mind, and not only that but - like Hawking (in this sense) - he's the sort of rare intellect whose affection and enthusiasm for his subject can be surprisingly infectious.
It is a shame he gets such a casual hammering from the media these days, and of course the sadly growing number of people who rely purely on the media for their opinions. Yes, he's said one or two things that don't quite fit into our modern political framework, but with the best will in the world he's been around a pretty long time, and when one focuses so keenly on one area it's only to be expected that one might not spend so much effort on the fads and fashions of expression.