21 replies to this topic

[Waspie_Dwarf]

Herschel intercepts asteroid Apophis

www.esa.int said:

ESA’s Herschel Space Observatory captured asteroid Apophis in its field of view during the approach to Earth on 5/6 January 2013. This image shows the asteroid in Herschel’s three PACS wavelengths: 70, 100 and 160 microns, respectively.

Credits: ESA/Herschel/PACS/MACH-11/MPE/B.Altieri (ESAC) and C. Kiss (Konkoly Observatory)

9 January 2013 ESA’s Herschel space observatory made new observations of asteroid Apophis as it approached Earth this weekend. The data shows the asteroid to be bigger than first estimated, and less reflective.

Catalogued as asteroid (99942) Apophis (previously 2004 MN4), it is often nicknamed ‘the doomsday asteroid’ in popular media, after initial observations made after its discovery in 2004 gave it a 2.7% chance of striking Earth in April 2029.

With additional data, however, an impact in 2029 was soon ruled out, although the asteroid will pass within 36 000 km of Earth’s surface, closer even than the orbits of geostationary satellites.  

Read more...

[keithisco]

The question (s) I have Waspie are:

• What is the assumed composition of this Asteroid (i.e. could it contain a large proportion of "Dirty" Cometary Ice hence the low Albedo, or is it Stony or Metallic)?
  
• What is the likelihood of it causing disruption to several Telecomms Satellites sat in Geostationary Orbit (at one of the LaGrange Points)?
  
• Is it rotating?
  
• Is it of near uniform shape, or does it have a non - regular topography?

I am assuming that at this distance from the Sun any Cometary effects would start to become apparent, and as this isnt the case, perhaps we can rule out any Ice component.

This is your field of expertise, and I really dont know where to start looking for definitive information, if you can fill in some of the  the blanks I would appreciate it

Edited by keithisco, 09 January 2013 - 01:40 PM.

[Waspie_Dwarf]

keithisco, on 09 January 2013 - 01:40 PM, said:

What is the assumed composition of this Asteroid (i.e. could it contain a large proportion of "Dirty" Cometary Ice hence the low Albedo, or is it Stony or Metallic)?

It is classed as an Sq asteroid, so it is stoney but with metals present.

keithisco, on 09 January 2013 - 01:40 PM, said:

What is the likelihood of it causing disruption to several Telecomms Satellites sat in Geostationary Orbit (at one of the LaGrange Points)?

Virtual none. It's not impossible that it could hit a satellite but it is highly unlikely. Even though large by NEO standards it is still a tiny object, it's gravitational field will be too small to disrupt a satellite unless it came very close.

keithisco, on 09 January 2013 - 01:40 PM, said:

Is it rotating?

I expect so, most asteroids do, but I don't know for sure..

keithisco, on 09 January 2013 - 01:40 PM, said:

Is it of near uniform shape, or does it have a non - regular topography?

I don't know, I'm not sure if that is know, it was quite distant in it's 2009 pass.

keithisco, on 09 January 2013 - 01:40 PM, said:

I am assuming that at this distance from the Sun any Cometary effects would start to become apparent, and as this isnt the case, perhaps we can rule out any Ice component.

If it was cometary in nature that would have been revealed in 2009 I suspect.

keithisco, on 09 January 2013 - 01:40 PM, said:

This is your field of expertise, and I really dont know where to start looking for definitive information, if you can fill in some of the  the blanks I would appreciate it

To call it my field of expertise is very flattering, thank you, but not accurate. The real experts forget more over breakfast than I've ever known.

[Merc14]

Hopefully the Russians plant that transmitter as they are planning as it would provide muuch new data on the above questions.

[Troublehalf]

I thought the point was they thought Apophis would go through the "keyhole" phase in 2029, which would mean a 100% collision chance in 2036.

Won't some people say this is just attempts to calm people down well in advance? But, who knows! The funny part is, if it did go through the keyhole phase, it would crash into Earth on Friday 13th.

[stevewinn]

I have a feeling this will be closer than expected during the return in 2036. - a question about the asteroid that killed the dinosaurs, im not sure if its fact or i've just heard it wrong. -  is it true that when the tip of this asteroid made contact with the earths surface the other end of the asteroid was 35,000 feet in the air? -  im sure i heard this in one of the early episodes of the 'Universe' is this true?

[Waspie_Dwarf]

stevewinn, on 10 January 2013 - 07:40 PM, said:

I have a feeling this will be closer than expected during the return in 2036.

Expected by who? It will pass EXACTLY at the distance calculated by the experts. Orbital mechanics are about precise measurements and calculations, NOT about feelings.

stevewinn, on 10 January 2013 - 07:40 PM, said:

a question about the asteroid that killed the dinosaurs, im not sure if its fact or i've just heard it wrong. -  is it true that when the tip of this asteroid made contact with the earths surface the other end of the asteroid was 35,000 feet in the air? -  im sure i heard this in one of the early episodes of the 'Universe' is this true?

That is about right. The Chixulub impactor was at least 10 Km in diameter, which is around 32,800 feet. However as it was travelling at around 15 - 20 Km/s it would have taken a fraction of a second, from start to finish, for the entire asteroid to have hit the Earth.

[Merc14]

Troublehalf, on 10 January 2013 - 07:29 PM, said:

I thought the point was they thought Apophis would go through the "keyhole" phase in 2029, which would mean a 100% collision chance in 2036.

Won't some people say this is just attempts to calm people down well in advance? But, who knows! The funny part is, if it did go through the keyhole phase, it would crash into Earth on Friday 13th.

The data is out there for all to see and many different instrumenst and many different people observing the thing so I doubt they are covering anything up.  Also, while this would be a major disaster it wouldn't be cibilization ending, I think teh projected impacts would equal 2.5 Krakatoas

[AsteroidX]

Apophis is a planet killer fwiw. But its getting hard to keep track of all the near misses lately. So I could have my near earths mixed up.

Edited by AsteroidX, 10 January 2013 - 08:08 PM.

[Merc14]

AsteroidX, on 10 January 2013 - 08:07 PM, said:

Apophis is a planet killer fwiw. But its getting hard to keep track of all the near misses lately. So I could have my near earths mixed up.

No, it most certainly isn't.  NASA has revised estimates down to 510 megatons http://neo.jpl.nasa....isk/a99942.html from an initial estimate of 1480MT which was quickly lowered to 880MT.  As comparisons Krakatoa is estimated to to have been 200MT and the Tsar bomb was 50MT.    The one that may have killed off the dinosaurs was in the millions of MT's.

[Waspie_Dwarf]

Merc14, on 10 January 2013 - 08:28 PM, said:

No, it most certainly isn't.

Agreed.

Merc14, on 10 January 2013 - 08:28 PM, said:

The one that may have killed off the dinosaurs was in the millions of MT's.

Over 100 million megatons.

Apophis is around 1/30th the diameter of the Chixulub impactor.

[stevewinn]

Waspie_Dwarf, on 10 January 2013 - 08:03 PM, said:

Expected by who? It will pass EXACTLY at the distance calculated by the experts. Orbital mechanics are about precise measurements and calculations, NOT about feelings.

Yes it will pass at the distance calculated for 2029, but what effect might gravity have - which then possibly alters its orbit, even if its only by a fraction it will need to be recalculate surely for the exact position for the 2036 pass. so what im saying is, until it passes in 2026 we wont know the outcome for 2036. am not one for conspiracies. but as someone famous once said in a galaxy far far away - i have a bad feeling about this.

Quote

That is about right. The Chixulub impactor was at least 10 Km in diameter, which is around 32,800 feet. However as it was travelling at around 15 - 20 Km/s it would have taken a fraction of a second, from start to finish, for the entire asteroid to have hit the Earth.

Jesus, just to think if you look up at a aeroplane flying over, which i believe normally fly at 30,000 feet then the back end of the asteroid reached that high. no wonder it killed the Dinosaurs.

[Waspie_Dwarf]

stevewinn, on 10 January 2013 - 09:54 PM, said:

Yes it will pass at the distance calculated for 2029, but what effect might gravity have - which then possibly alters its orbit, even if its only by a fraction it will need to be recalculate surely for the exact position for the 2036 pass.

The change in orbit can be calculated in advance IF the distance that the asteroid will pass Earth in 2029 is known with enough accuracy. That calculation has now been made and an impact in 2039 ruled out (see THIS THREAD).

stevewinn, on 10 January 2013 - 09:54 PM, said:

so what im saying is, until it passes in 2026 we wont know the outcome for 2036.

Totally wrong. We've been able to calculate orbits with extraordinary accuracy since the days of Kepler and Newton. The only reason there was doubt about the possibility of an an impact in 2036 was because the orbit was not known with sufficient accuracy. Now that the orbit has been refined the uncertainty can be reduced to the point where an impact in 2036 can be ruled out.

stevewinn, on 10 January 2013 - 09:54 PM, said:

am not one for conspiracies. but as someone famous once said in a galaxy far far away - i have a bad feeling about this.

Fortunately scientists rely on mathematics, observations, evidence and cold hard facts not guess work and "bad feelings" and Star Wars.

[Kafkaesque]

Waspie_Dwarf, on 10 January 2013 - 08:36 PM, said:

Agreed.


Over 100 million megatons.

Apophis is around 1/30th the diameter of the Chixulub impactor.

At least if we get hit we don't all die.. Silver lining.

[dan-paul-mark]

i heard that the solar systems orbit fluctuates up and down, and the last time we were at the point we're heading towards soon; which is a large asteroid belt, was when the dinosaurs were wiped by the collision. anyone no if this is true?