The Space Reviewin association with SpaceNews

GPS satelite illustration
Satellite systems like GPS seem important, but how can you measure their effectiveness against alternative systems? (credit: Boeing)

The metrology of space system effectiveness

Some time ago, I had the opportunity to observe and provide advice to a number of developing senior officers who were actively engaged in an operational planning process for a fictitious wartime scenario. As the space subject matter expert (or SME), I was tasked with assisting and answering exercise questions relative to the employment of space systems. From the very start, I could see that although there was a general impression that, yes, space systems were important, there was also some confusion as to how such assets should be interpreted in terms of their capabilities and limitations. I soon realized that while the value of an armored battalion over an infantry battalion was clearly understood, the value of satellite communications over terrestrial nets was not. Or, whereas satellite imagery was accepted as being obtainable, it was not clearly understood the conditions that had to be met nor the impact of that capability on the overall campaign.

Generally, the decision to go with a space system is not taken lightly and in fact must be weighed against other available options to get from situation A to desired outcome B.

These realizations got me thinking. Before the decision to spend some hundreds of millions of dollars towards the acquisition of a satellite or even a constellation of satellites can be taken, the obvious question is: Do I need a space system to meet this requirement? Is this the most effective use of capital on hand? Does having access to a space capability infer a clear advantage over competitors/enemies?

Generally, the decision to go with a space system is not taken lightly and in fact must be weighed against other available options to get from situation A to desired outcome B. Taken further, if we match up the capabilities of two adversaries and their various means to accomplish certain tasks/missions, how does availability or non-availability of space access complicate the decision-making process?

Realistically, space systems (or any resource for that matter) should be employed to control, indeed save, resources while still meeting the mission objective. These resources may be time, money, or even people. And so, the evaluation of effectiveness rests on being able to convince the decision-making (thus funding) body that, indeed, the employment of space systems is a better investment than terrestrial arrangements. Or, in a military sense, a clear advantage in space system effectiveness exists that will effect the operational outcome.

In truth, we do not really have to confine our discussion to military campaigns but instead point to the government’s growing use of/access to space systems in the areas of the economy, public safety, and the environment. Saving lives is probably the easiest to justify and yet the most difficult to link directly to space system access. Satellite communications (SatCom), satellite navigation (SatNav), and imagery were all employed at some point to mitigate the effects of Hurricane Katrina. But was it possible to equate access to savings, whether it was people, money, or time?

One possible way to aid the decision-maker is to construct some instrument that could provide guidance towards either acquiring and employing, or denying space systems. This instrument could take the form of an “Effectiveness Index” such that a number of agreed-upon indicators could be weighted and then applied to a given situation. Based on the resultant score, a decision-maker could act.


As possible indicators, we might consider items such as:

  • Available bandwidth. Operation Desert Storm (1991) reportedly utilized an average data rate of approximately 99 MB/sec, whereas Operation Enduring Freedom (2001) requirements had reached almost 700 MB/sec, with proposed new systems aiming for even more.
  • Average time/error of units (ordnance) to objective areas (targets) using satellite navigation. More bombs on target may entail less expense and possibly shorter operations.
  • Average time from request to delivered product (to the decision-maker) of satellite imagery. Recently, Marine Corps General James E. Cartwright, Commander of US Strategic Command, emphasized this by saying: “21st century warfare requires getting vital information into the war-fighting hands as soon as possible.”
  • Number of friendly fire incidents before/after employing blue-force tracking systems. Based on the political fallout from these tragedies, their reduction via space system support cannot be overlooked.


Since some indicators may be more important than others, a weighting system should be constructed so that a realistic score is tabulated. For instance, available bandwidth to pass voice and data may be more valuable than the existence of space-based radar imagery. Therefore, we would place more emphasis on bandwidth availability.

Further, we may need to adjust the weighting of space imaging and reconnaissance assets in light of available terrestrial sources. Likewise, we might alter the weighting of dedicated satellite communication assets versus commercial assets, as there are often significant differences in availability and capability between them.

We might also wish to consider the asset’s vulnerability and reliability. Although it may provide high value information, could the system be easily destroyed and/or rendered ineffective? If such a situation were to have a deep impact on operations, we might reduce the asset’s associated indicator value.

Use of score

Of course, the development of such a tool must be motivated by the expectation of its implied use: a decision on space systems will be made. Perhaps based on a threshold-crossing score, an organization decides to invest in a satellite navigation constellation; a military commander decides to attack an adversary’s satellite communication links; a United Nations organization decides to implement a satellite imagery sharing process for developing nations, etc.

Decisions on space systems cannot be taken lightly. Still, they have value and over the years have proven to be effective in numerous situations and campaigns.

We should also acknowledge that an “Effectiveness Index” would differ from one government or military to another, with different indicators, weightings, and possibly decision thresholds. Whereas the US may value global satellite communications very highly, a smaller nation in terms of size and resources may place less emphasis on SatCom and instead prefer access to SatNav information for the positioning of its units.


Decisions on space systems cannot be taken lightly. Such systems can be expensive, complicated, and vulnerable all at the same time. Still, they have value and over the years have proven to be effective in numerous situations and campaigns. The key decision-making problem is thus how to construct a tool that will aid decision-makers in properly accounting for the availability or non-availability of space resources, whether it is in the domestic context or in considering the capabilities and limitations of an adversary. This tool must indicate the key effectiveness areas as well as properly weigh one against the other. If done properly, such a tool may be useful to direct the acquisition, employment, or even the denial of space systems.