From: TerryMoselat

Date: 12 February 2009 00:34:33 GMT

Subject: Satellites collide, IAA lectures, Armagh lecture, Comet Lulin

Hi all,


PREAMBLE: I've had problems with my astronomy email address lists, with several lists getting combined, and at least one group possibly deleted, so I've had to copy & paste a lot! My new list may contain the names of anyone that I've ever sent an email to, so there may be names here that should not be - if so, I apologise! I am gradually working through wrong inclusions & duplicates & removing them, but there may still be some anomalies.  If you have got two copies of this email, I apologise, and if you have got it by mistake and want to be removed from this list, please let me know by return. Thanks.


1. NEWSFLASH!  Two major satellites have collided in space! - See below for details.


2. The next IAA meeting will be on Wednesday 18 February, at 7.30 p.m., in the Bell Lecture Theatre, Physics Building, Queen's University, Belfast. It will be a 'double-header', with Dr Kate Russo speaking on Solar Eclipses: "Chasing the Shadow of the Moon"; and Terry Moseley speaking on "400 Years of the Telescope".

  Admission is free, including light refreshments, and all are welcome. 

   Free parking is available on the main campus, beside the lecture theatre, in the evenings - entrance via University Square.

   The IAA gratefully acknowledges the support of the Astrophysics and Planetary Science Division of the Department of Physics, QUB, in sponsoring these lectures.


3. Prof. David Southwood Lecture in Armagh:

Armagh Observatory and Armagh Natural History and Philosophical Society 

joint public lecture to celebrate International Year of Astronomy 2009:

"Space in a Modern Society"; Rotunda Lecture Theatre, St. Patrick's Trian, Armagh

15:00 to 16:00, Saturday 14th March 2009

    BY: Professor David Southwood, Director of Science and Robotic Exploration, European Space Agency, Headquarters, Paris.

   Summary: With the start of the space age, both the universe and the Earth changed or - at least - mankind's perception of both dramatically changed.  50 years on we can wonder at the vast increase in our knowledge of the Earth, solar system, and the stars and galaxies that access to space has provided.  Space did indeed give us our first capacity to look at our

own planet in a truly global manner.  It even allowed to manage things on a global scale. Who would have predicted in 1957 that now we would use space to navigate our cars? Not many. However, at the same time, how many back then would have been sure that by now we would have had a base on the Moon? Quite a few, no doubt. What then is space about: 

exploration, exploitation, inspiration, education, knowledge? And, why does a developed society need to care?

    Tea and biscuits will be served after the lecture, where there will be 

an opportunity to ask questions.

    This is a free public lecture open to all. Everyone is welcome.  In 

order to obtain a ticket to reserve your place at the lecture, please 

contact Mrs Aileen McKee at the Armagh Observatory, College Hill, 

Armagh, BT61 9DG. Tel: 028-3752-2928, E-mail: ambnat


4.  Comet Lulin is now brightening, and should be around 4th magnitude later this month. Martin McKenna from Maghera reports that he has now been seen it with the unaided eye. It's currently a morning object, but is becoming better placed for viewing each night. More details later


 (This is from, used with grateful acknowledgement)

Two satellites collide in orbit




   In an unprecedented space collision, a commercial Iridium communications satellite and a presumably defunct Russian Cosmos satellite ran into each other Tuesday above northern Siberia, creating a cloud of wreckage, officials said today. 



An artist's concept of an Iridium satellite orbiting the Earth. Photo: Iridium


The international space station does not appear to be threatened by the debris, they said, but it's not yet clear whether it poses a risk to any other military or civilian satellites.

"They collided at an altitude of 790 kilometers (491 miles) over northern Siberia Tuesday about noon Washington time," said Nicholas Johnson, NASA's chief scientist for orbital debris at the Johnson Space Center in Houston. "The U.S. space surveillance network detected a large number of debris from both objects."

One source said nearly 300 fragments were being tracked, but Johnson said it was not yet clear how much debris was generated.

"It's going to take a while," he said. "It's very, very difficult to discriminate all those objects when they're really close together. And so, over the next couple of days, we'll have a much better understanding. But it's at a minimum, I think we're talking many, many dozens, if not hundreds."

Asked which satellite was at fault, Johnson said "they ran into each other. Nothing has the right of way up there. We don't have an air traffic controller in space. There is no universal way of knowing what's coming in your direction."

Iridium Satellite LLC operates a constellation of some 66 satellites, along with orbital spares, to support satellite telephone operations around the world. The spacecraft, which weigh about 1,485 pounds when fully fuelled, are in orbits tilted 86.4 degrees to the equator at an altitude of about 485 miles. Ninety-five Iridium satellites were launched between 1997 and 2002 and several have failed over the years.

Representatives of Iridium did not immediately return calls for additional details.

Johnson said the collision Tuesday was unprecedented.

"Nothing to this extent (has happened before)," he said. "We've had three other accidental collisions between what we call catalogue objects, but they were all much smaller than this and always a moderate sized objects and a very small object. And these are two relatively big objects. So this is a first, unfortunately."

As for the threat posed by the debris, Johnson said NASA carried out an immediate analysis to determine whether the space station faced any increased risk. The station, carrying three crew members, circles the globe at an altitude of about 220 miles in an orbit tilted 51.6 degrees to the equator.

"There are two issues: the immediate threat and a longer-term threat," he said. "It turns out, when you have a collision like this the debris is thrown very energetically both to higher orbits and to lower orbits. So there are actually debris from this event which we believe are going through the space station's altitude already. Most of it is not, most of it is still clustered up where the event took place. But a small number are going through station's altitude.

"Yesterday, we did an assessment of what the risk might be to station and we found it's going to be very, very small. As time goes on, those debris will (come down) some over months, most over years and decades and as the big ones come down they'll be tracked, we'll see them and the worst-case scenario, we'll just dodge them if we have to. It's the small things you can't see are the ones that can do you harm."

Asked if other satellites might be at risk, Johnson said "technically, yes. What we're doing now is trying to quantify that risk. That's a work in progress. It's only been 24 hours. We put first things first, which is station and preparing for the next shuttle mission."

Most, if not all, of the debris is expected to eventually burn up in Earth's atmosphere."

Clear Skies,

Terry Moseley