NASA SAFETY STANDARD

NASA SAFETY STANDARD FOR MINIMIZING ORBITAL DEBRIS
The motivation for this work is the NASA Safety Standard NSS 1740.14 "Guidelines and Assessment Procedures for Limiting Orbital Debris." The relevant portion of the Standard starts on page 6-3:

General Policy Objective - Postmission Disposal of Space Structures.

Item 6-1: Disposal for final mission orbits passing through LEO: A spacecraft or upperstage with perigee altitude below 2000 km in its final orbit will be disposed of by one of three methods.

The method of interest relevant for this paper is the atmospheric reentry option:

Option a: Leave the structure in an orbit in which, using conservative projections for solar activity, atmospheric drag will limit the lifetime to no longer than 25 years after completion of mission. If drag enhancement devices are to be used to reduce the orbit lifetime, it should be demonstrated that such devices will significantly reduce the area-time product of the system or will not cause the spacecraft or large debris to fragment if a collision occurs while the system is decaying from orbit.

The NASA standard applies only to NASA spacecraft and even then only to completely new spacecraft designs. New versions of existing designs are to make a "best effort" to meet the standard, but will not be required to change their design to do so. The DoD has adopted the NASA standard with the same provisos. An Interagency Group report has recommended that the NASA Safety Standard be taken as a starting point for a national standard. It is NASA's recommendation to the Interagency Group that the safety requirement be phased in only as we reach consensus internationally. This consensus is being sought through the International Debris Coordination Working Group, whose members are Russia, China, Japan, ESA, UK, India, France, Italy, and the US.

Thus, although the NASA Safety Standard in its present form is not the "Law", the existence of the standard means that at some time in the future a similar requirement may be imposed on all spacecraft. The Terminator Tether will be a low-cost, low-mass, low-"area-time-product", reliable, safe means for meeting that requirement.