A Filipino physicist dismissed the Aquino government's fears over the upcoming North Korean satellite launch as mere "overreaction" and "panic".
Dr. Giovanni A. Tapang, a physicist and chairman of the Advocates of Science and Technology for the People said that "the overreaction of the Aquino government to the launch belies its sincerity in facing the supposed risks."
Tapang said that the government should seek a dialogue with North Korea instead of joining the fray and panic with "other countries such as the US, Japan, South Korea and Taiwan."
Dr. Tapang noted that "for the past few days, fears from the upcoming launch of a North Korean satellite were all over the news."
The Philippine Interior and Local Government Secretary Robredo urged people stay indoors and asked fishermen to stay at port "to avoid the debris from the rocket."
Department of National Defense Secretary Voltaire Gazmin, on the other hand, called on the US to monitor the path of the rocket, while NDRMMC Director Benito Ramos already announced a no-fly zone covering practically all of Northern Luzon.
Dr. Tapang, however, wondered "why all the hoopla about this satellite test." He recalled that South Korea also "tested two rockets several years ago." In his statement, Tapang raised a few interesting points:
It (South Korea) tried to launch a satellite at Naro last August 25, 2009 and another last June 10, 2010. Both tests failed to deploy a satellite in orbit. What was more interesting was that the path that was taken by these rockets to launch the satellites were similar to that planned by the DPRK but we heard neither panic nor warnings from the government. Debris from the South Korean test fell in Darwin, Australia."
Dr. Tapang clarified the science behind the North Korean satellite launch explaining in detail how it usually works. The extended quote below was from his Facebook Note which can be found here:
The upcoming test will be the fourth launch attempt by the Democratic People's Republic of Korea (DPRK). Their most recent one was during 2009 that used a similar rocket, the Unha-2, to what is planned to be launched this month. Both rockets use three stages to boost its satellite to its orbit but the direction of flightof the upcoming test is from north to south while in 2009, Unha-2 flew eastward over Japan.
What does it mean to have three stages in a rocket? The target of a rocket launching a satellite is to reach a certain velocity and height so that it can deploy its payload into orbit. It does this by firing successive rockets (called stages) and discarding them when its fuel has been spent. The first stage is the first part of the rocket and provides enough lift to bring the whole rocket up from the ground. When its fuel is spent, it is separated from the rest and falls down to the earth. The second stage functions similarly and is also discarded when its fuel is empty. A third stage then bridges the remaining gap to orbital height and is also used toposition the satellite correctly into a stable position so that it can orbit the earth. Once the first and second stage leaves the main body of the rocket, these pieces would essentially just follow projectile motion until splashdown.
For the April 2012 test, the first stage of the rocket will fall in international waters somewhere west of South Korea just a few hundred kilometers from its launch site. The second stage's splashdown area is around 200 kilometers away east ofPhilippines.
When you throw a rock, you can increase its range by either of two things. Throw it harder or change the angle at which you would launch it. The same principle could be used when looking at whether the DPRK rocket's second stage can overshoot its projected splashdown. It either separates from the third stageat a faster velocity than it was supposed to, or it was launched at a different angle that makes the range of the second stage longer. One should note that the DPRK's splashdown range already takes into consideration a wide margin of error as evidenced by the wide area that they reported to the international maritime authorities.
Another concern is that the second stage can hit Cagayan Valley and Eastern Luzon. There is a small possibility that this will happen if the second stage booster was launched at angle slightly to the West of its original path. Note again that the splashdown range has already taken into account around a margin of error in the direction of its flight.
Another concern raised by the government is that if the second stage explodes, debris might reach the Philippines. When a moving object explodes while in flight, the center of mass of its constituent parts will still follow the path of the original object. This is a well-known result from the physics of inertial motion.What this means is that even if the second stage booster explodes in mid-air, its projected trajectory will remain within the original projection give or take a few meters due to the explosion. These debris will not veer far from the original splashdown. One should note however that typically the second stage, when separated from the rocket, is essentially a spent shell without fuel or explosive parts in it. It could however break up or burn up upon re-entry but its pieces will still be near the original splashdown's area.
Dr. Tapang concluded his analysis saying that the Philippine government's "disaster preparedness is unprecedented in this case since we do not see such level of activity when typhoons arrive in the country. It seems that they can indeed mobilize and prepare against a very small risk from space debris but seems to be Noynoying on others.##