Space Shuttle Liftoff The international Lachs Space Law Moot problem for 2007 is a very convoluted scenario (politically) in which the Skyhunter space plane atop a booster rocket makes a sea launch into low Earth orbit. Unfortunately, during the launch some objects, including some of the space plane insulation, fall off and hit two ships within the launch zone causing both damage to property and loss of life. To follow the further discussion please refer to the full problem.

Although the scenario is certainly an exciting problem with many diverse legal aspects for the moot, we would like to draw attention to some physical difficulty with the facts. In particular we would address three potential conflicts with physical reality, for as the Honourable Justice French (Federal Court of Australia) has stated, it is very important to consider the supposed facts from a physical point of view, before tackling the legal issues. For it may turn out that the assumed facts are in fact not factual at all, and we will then need to determine what in fact are the true facts.

We would contend that:

  1. It is not possible for any object falling off the Skyhunter at the launch plus eight second mark to hit either of the two ships that are 15 and 18 km away respectively.
  2. A pilot/commander knowing that he has a spacecraft with damaged re-entry insulation tiles, who makes a decision to return to Earth immediately, should probably be declared mentally insane. Any experienced pilot knows it is much safer to stay in orbit until a full evaluation of the exact extent of the damage has been undertaken. The danger lies not in orbit but in re-entry.
  3. It is not possible for a re-entry undertaken after approximately one orbit of the planet to land within a few hundred kilometres of the launch site.

1 What hit the Condor and the Barracuda was not from the Skyhunter

We quote here from Jim Cornish :
"It takes five seconds for the shuttle to clear the 85 metre tower and its 30 metre lightning rod. By the end of the eighth second, the shuttle has traveled only twice its own length in distance (and) has already accelerated to 161 kilometres per hour."

Thus at eight seconds, the Space Shuttle is still vertically above the launch pad, but only by a distance of 112 metres. It is certainly not possible for any objects falling off the Shuttle at this height to reach, let alone do damage to anything 15 kilometres away.

Of course the Skyhunter is much newer technology that the Space Shuttle, and we may expect it to have covered a greater distance in eight seconds. Can we calculate a reasonable distance? We can indeed, and we will show that even with the most advanced technology (not) possible, the distance covered is not adequate to fit the assumed facts.

In what we might call the "technology unlimited" solution we call as our witness the human body. Although fighter pilots regularly experience accelerations of 6 to 8 g (gee or Earth gravities) and even greater, they do so wearing anti-g suits and the duration of such accelerations are very short (during high speed turns). In paying passenger space operations, it is not standard practice to exceed 3g. This is to ensure that relatively unfit passengers (and rock stars are normally not known for their excessive fitness) with limited high-g experience make it into orbit safely without medical complications (for which the passenger might well sue).

Now one Earth gravity corresponds to an acceleration of just under 10 metres per second per second. So 3 g = 30 metres per second. We will thus allow our space plane the ability to maintain this acceleration right from liftoff. All we now need is a little formula that the Italian scientist Galileo gave to us nearly 400 years ago. This says that
distance_travelled = 1/2 x acceleration x time x time
Putting in the values of 30 m/s2 for acceleration and 8 seconds for time we can compute that the distance travelled is 960 metres or just under one kilometre. And this distance will be mostly vertically above the launch pad. Even were we to allow the Skyhunter to roll to an angle of 45 degrees to the vertical immediately after clearing the pad, the horizontal distance from the launch ship is still well under one kilometre.

For safety reasons, a launch is not attempted in high winds, and usually a wind speed of less than 10 km/hr is required. The only object that could cover a distance of 14km horizontally to hit the closest ship would be a low density object such as a balloon that took at least an hour to drift slowly to the ground as it was carried this distance by the prevailing winds. Even if it was assumed that such an object did fall from the Skyhunter, it would not result in the damage maintained. We can safely conclude that whatever hit the two ships of Emeraldian registry had no connection to the debris that fell off the spacecraft at eight seconds into the launch.

2 Problems with missing insulation

Approximately one and a half hours after launch (at which time the Skyhunter space plane would have completed one full orbit of the Earth), there is a communication between the Pilot/Commander and the Flight Director on the launch ship. To quote: "According to calculations by the control computers, the loss of (insulating) material did not jeopardize the mission and so the flight could proceed according to the nominal conditions. The Flight Director decided to continue with the flight. This decision was questioned by Van den Bergh; his experience of space flights told him to abort the mission and to land as soon as possible, considering the loss of heat protection elements."

While certainly it is not impossible that the Commander, a military Colonel, would make such a decision, it would not be due to his "experience of space flights". Heat protective insulation is to protect a spacecraft from the massive energy that must be bled from the vehicle in the re-entry process, and the subsequent extremely high temperatures (thousands of degrees) that result. While in orbit the space plane is in no danger whatever. The danger only occurs during re-entry to Earth from orbit. No spacecraft commander would make such a decision in his right mind. Only mental incapacitation could cause such a rash judgement. It would be much safer to stay in orbit while a full evaluation of the consequences of re-entry were evaluated. This would involve inspection of the space plane surfaces by a high resolution infrared telescope on the ground. At least two such instruments existed on the Earth in 2005: a USAF facility on the island of Maui and the UK Infrared Telescope on Mauna Kea on the island of Hawaii. Under the UN 1967 OST and 1968 ARRA, at least one of these could have been co-opted to assist SkyQuest.

3 Landing Site

While the scenario does not indicate the exact time of the deorbit burn, the statement that the Commander decided "to land as soon as possible", strongly suggests that it was made shortly after 16:04. Having completed approximately one complete orbit (orbital period of a space object at the nomimal height of 360 km is about 90 minutes), the spacecraft might be thought to be back over the vicinity of Emeralda from whence the launch took place. Were it not for the Earth's rotation this would in fact be the case. But the Earth does rotate, and in 90 minutes has rotated through about 22 degrees. In equatorial regions, or low latitude temperate regions, this corresponds to a surface distance of around 2000 km. At the poles the distance would of course be zero. So it is safe to assume that at the time of re-entry initiation, the Skyhunter is probably less than 3000 km from Emeralda. Now, the re-entry process requires around 8000 km of distance to bleed off the orbital energy at a rate that is not to detroy the vehicle. So it is highly unlikely that the Skyhunter could have come down anywhere in Emeraldan sovereign air or sea space.

Spacecraft Reentry

We will concede that items 2 and 3 above are not impossibilities, but only extremely implausible based on current reality.
And we would also point out that all three problems we have addressed could have been eliminated by the authors of the moot problem with very little compromise to the legal scenarios stated (eg the insulation and other objects could have fallen off a little later in the ascent).
Our purpose in making these comments is to suggest that those who set future moot problems should use the enormous expertise of their parent organisation, the International Astronautical Federation, to review the scientific and engineering aspects of the problem, to ensure the soundness of the scenario in all possible ways, and to thus further improve a very successful educational opportunity for many students around the world.

{Acknowlegement - both images used on this page are due to NASA}