Apophis: A close call…

The Earth is under constant bombardment. Each year, many fragments of debris hit our planet. Fortunately for us, most are so small that they burn up harmlessly in the atmosphere.
However, there are hundreds of larger asteroids orbiting near the Earth. Many scientists now believe that one of these hit the Earth 65 million years ago, killing the dinosaurs, along with 90% of all life on the planet. What is more, it is only a matter of time before the Earth is hit again.

Apophis – previously known by its provisional designation 2004 MN4 – is a Near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a relatively large probability that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However there remained a possibility that during the 2029 close encounter with Earth, Apophis would pass through a "gravitational keyhole", a precise region in space no more than about 400 meters across, that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006.

Additional observations of the trajectory of Apophis revealed the "keyhole" would likely be missed and on August 5, 2006, Apophis was lowered to a Level 0 on the Torino Scale – a method for categorizing the impact hazard associated with Near Earth Objects. As of October 19, 2006 the impact probability for April 13, 2036 is estimated at 1 in 45,000. 

Basic data...

Apophis belongs to a group called the "Aten asteroids", asteroids with an orbital semi-major axis less than one astronomical unit. This particular one has an orbital period about the Sun of 323 days, and its path brings it across Earth's orbit twice on each passage around the Sun.

It was discovered on June 19, 2004, by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi of the NASA from Kitt Peak National Observatory.

When first discovered, the object received the provisional designation 2004 MN4, and news and scientific articles about it referred to it by that name. When its orbit was sufficiently well calculated it received the permanent number 99942, the first numbered asteroid with Earth-impact solutions. Receiving a permanent number made it eligible for naming, and it promptly received the name "Apophis" as of July 19, 2005. Apophis is the Greek name of the Ancient Egyptian god Apep, "the Destroyer", who dwells in the eternal darkness of the Duat (underworld) and tries to destroy the Sun during its nightly passage.

Close approaches...

After the Minor Planet Center confirmed the June discovery of Apophis, the next close approach was computed to be April 13, 2029. On that date, it will become as bright as magnitude 3.3 (visible to the naked eye from rural and some darker suburban areas, visible with binoculars from most locations). It is important to note that the close approach in 2029 will substantially alter the object's orbit, making predictions uncertain without more data.

The NASA report on December 24, 2004, mentioned impact chances of "around 1 in 62", which was widely reported in the media, resulting in an update to the initial report and an upgrade to a Torino scale rating of 4. But later with observations from around world through 2006 resulted in Apophis being lowered to Torino Scale 0 on August 6, 2006. 

Since the odds of impact are known to be very low, the possible effects of an impact are largely irrelevant. However, the initial reports resulted in widespread discussion on many Internet forums, including armchair speculation about exactly where Apophis (then known only as 2004 MN4) would hit and what would happen when it did.
NASA estimated the energy that Apophis would have released if it struck Earth as the equivalent of 400 megatons of TNT. The impacts which created the Barringer Crater or caused the Tunguska event are estimated to be in the 10-20 megaton range. The 1883 eruption of Krakatoa was the equivalent of roughly 200 megatons.
The exact effects of any impact would have varied based on the asteroid's composition, and the location and angle of impact. Any impact would have been extremely detrimental to an area of thousands of square kilometres, but would have been unlikely to have long-lasting global effects, such as the initiation of an impact winter.

The astroid Apophis was a close call and also was an eye-operner for all the scientists around the world to be ready for any future hazards of astroids or comet impacts.

Thilina Heenatigala
General Secretary
Sri Lanka Astronomical Association

Playing ‘space billiards’ to save earth - interview with Dr. Sima Adhya

As a part of a programme conducted by British Council, Colombo to improve the science knowledge among Sri Lankan students as well as the general public, four UK scientists delivered their lectures last week in leading schools in Colombo and Kandy. 

Thilina Heenatigala, General Secretary of Astronomical Association of Sri Lanka had a brief interview with the team’s space scientist Dr. Sima Adhya. Indian born Adhya studied natural sciences at Cambridge, and read her PhD at UCL on how spacecrafts wobble in their orbits due to sunlight. Her PhD was in collaboration with a team at NASA’s Jet Propulsion Laboratory, where some of the techniques she developed have now been included in NASA’s routine orbit determination software.

As a space mission scientist she works at the Space Department of QinetiQ, where her duties are to look at every aspects of a space mission; analysing data, writing programmes and putting in place all the systems that are needed. She was also the runner up of FameLab Competition, which is a British national competition to find the new voices in science and engineering.

Q: What kind of research are you involved in as a space scientist? 
A: Well, I work as a Space Mission Scientist in the Space Department of QinetiQ, based in the UK and am currently working for the European Space Agency on a mission study designed to deflect an asteroid. Actually, it is a practice run to test our technology, in case an asteroid is on a collision course with Earth in the future. 

Q: Could you explain the mission plan?
A: The plan is to deflect an asteroid. You can think of it as space billiards, but on a vast table with tiny, tiny balls! What we’re going to do is hit a very small asteroid which is very far away – about 30 million miles – with a spacecraft. There are actually two spacecrafts. The first one would basically orbit around the asteroid and map it, while taking measurements such as mass and density etc. And the second one will lock onto it and then smash into the asteroid at about 10km per second, which is pretty fast, while the first spacecraft will be monitoring the whole collision. As a space scientist, this is a kind of mission you dream of being involved in.

Q: We have seen the nightmare scenario of asteroid collision in movies like, Armageddon and Deep Impact, but what are the chances of such an asteroid hitting the Earth?
A: Well, you have to say that the chance of an asteroid hitting us is very slim. Though we have predicted an asteroid will come very close to the earth in 2029, that asteroid named Apophis is expected to pass within 30,000 km from the Earth.

Q: Should we earthlings be afraid or not?
A: If it’s something very big, or if it’s a comet, I would say that we don’t have any hope for the moment, so might need to be a little afraid. But I’m sure if something like that happens all of the states around the world would cooperate.” 

Q: How did you get interested in science?
A: I was always interested in science. I found pure science and mathematics the most interesting and rewarding. The theory of evolution inspired me too. It makes you to see the world in a different manner. Since my childhood I wanted to be an astronaut. But unfortunately, UK doesn’t fund manned-missions at the moment. Maybe in the future I might ravel at least as a space tourist if the price ever becomes as normal as regular travelling costs.

Q: What is the purpose of your visit to Sri Lanka?
A: Actually I’m here to do a science workshop sponsored by your local British Council. I have been visiting quite a few schools this week in Colombo and Kandy, and trying to inspire the young students to pursue a career in science.

Q: How is the feedback on your programmes in Sri Lanka?
A: The response has been fairly good though some students were shy to ask questions. But in some places they didn’t let me go. After my 45 minute talk in Kandy, I had to answer their questions for another 45 minutes. So, it has been a very interesting visit. 
It’s been hard work, but it’s been rewarding, quite stretchy but challenging. I’m very grateful; people here have been really welcoming.

Q: What do you think of the science knowledge of Sri Lankan students?
A: Sometimes it is a bit hard to tell, but I have had some really interesting questions from students. But I don’t see any difference between the students back home and here.

Q: Do you have any suggestions for us?

A: Since I’m staying only a few days here I really can’t suggest anything specific. But I think organising something like FameLab would be an interesting step forward. Oh!! And FameLab is a National Competition held in UK, it’s more like an American Idol of the scientific world. I’m one of the finalists of last year’s competition. Actually, it makes science more fun.

Thilina Heenatigala.