PI -- Terminal Planetary Defense

We present a practical and effective method of planetary defense that allows for extremely short mitigation time scales. The method uses an array of small hypervelocity kinetic penetrators that pulverize and disassemble an asteroid or small comet. This mitigates the threat using the Earth's atmosphere to dissipate the energy in the fragment cloud. The system allows a planetary defense solution using existing technologies. This approach will work in extended time scale modes where there is a large warning time, as well as in short interdiction time scenarios with intercepts of minutes to days before impact. In longer time intercept scenarios, the disassembled asteroid fragments largely miss the Earth. In short intercept scenarios, the asteroid fragments of maximum $\sim$10-meter diameter allow the Earth's atmosphere to act as a "beam dump" where the fragments burn up and/or air burst, with the primary channel of energy going into spatially and temporally de-correlated shock waves. It is the de-correlated blast waves that are the key to why PI works so well. The effectiveness of the approach depends on the intercept time and size of the asteroid, but allows for effective defense against asteroids in the 20-1000m diameter class and could virtually eliminate the threat of mass destruction posed by these threats with very short warning times, though longer warning is always preferred. A 20m diameter asteroid ($\sim$0.5Mt, similar to Chelyabinsk) can be mitigated with a 100s prior to impact intercept with a 10m/s disruption. With ~1m/s internal disruption, a 5 hours prior to impact intercept of a 50m diameter asteroid ($\sim$10Mt yield, similar to Tunguska), a 1 day prior to impact intercept of 100m diameter asteroid ($\sim$100Mt yield), or a 10-20 day prior to impact intercept of Apophis ($\sim$370m diameter, $\sim$4Gt yield) would mitigate these threats.Comment: 174 pages, 130 figures. Published in Advances in Space Research (ASR) 10-22; https://www.sciencedirect.com/science/article/pii/S027311772200939

Pioneer Mars surface penetrator mission. Mission analysis and orbiter design

The Mars Surface Penetrator mission was designed to provide a capability for multiple and diverse subsurface science measurements at a low cost. Equipment required to adapt the Pioneer Venus spacecraft for the Mars mission is described showing minor modifications to hardware. Analysis and design topics which are similar and/or identical to the Pioneer Venus program are briefly discussed

SSTAC/ARTS review of the draft Integrated Technology Plan (ITP). Volume 8: Aerothermodynamics Automation and Robotics (A/R) systems sensors, high-temperature superconductivity

Viewgraphs of briefings presented at the SSTAC/ARTS review of the draft Integrated Technology Plan (ITP) on aerothermodynamics, automation and robotics systems, sensors, and high-temperature superconductivity are included. Topics covered include: aerothermodynamics; aerobraking; aeroassist flight experiment; entry technology for probes and penetrators; automation and robotics; artificial intelligence; NASA telerobotics program; planetary rover program; science sensor technology; direct detector; submillimeter sensors; laser sensors; passive microwave sensing; active microwave sensing; sensor electronics; sensor optics; coolers and cryogenics; and high temperature superconductivity

Optimization techniques applied to passive measures for in-orbit spacecraft survivability

The purpose of this research is to provide Space Station Freedom protective structures design insight through the coupling of design/material requirements, hypervelocity impact phenomenology, meteoroid and space debris environment sensitivities, optimization techniques and operations research strategies, and mission scenarios. The goals of the research are: (1) to develop a Monte Carlo simulation tool which will provide top level insight for Space Station protective structures designers; (2) to develop advanced shielding concepts relevant to Space Station Freedom using unique multiple bumper approaches; and (3) to investigate projectile shape effects on protective structures design

An experimental study of ultrasonic vibration and the penetration of granular material

This work investigates the potential use of direct ultrasonic vibration as an aid to penetration of granular material. Compared with non-ultrasonic penetration, required forces have been observed to reduce by an order of magnitude. Similarly, total consumed power can be reduced by up to 27%, depending on the substrate and ultrasonic amplitude used. Tests were also carried out in high-gravity conditions, displaying a trend that suggests these benefits could be leveraged in lower gravity regimes

The Viking seismometry

Efforts were made to determine the seismicity of Mars as well as define its internal structure by detecting vibrations generated by marsquakes and meteoroid impacts. The lack of marsquakes recognized in the Viking data made it impossible to make any direct inferences about the interior of Mars and only allowed the setting of upper bounds on the seismic activity of the planet. After obtaining more than 2100 hours worth of data during the quite periods at rates of one sample per second or higher, the Viking 2 seismometer was turned off as a consequence of a landing system failure. During the periods when adequate data were obtained, one event of possible seismic or meteoroid impact origin was recognized; however, there is a significant probability that this event was generated by a wind gust

SSTAC/ARTS review of the draft Integrated Technology Plan (ITP). Volume 1: Plenary Session

Briefings from the plenary session of the conference on SSTAC/ARTS Review of the Draft Integrated Technology Plan (ITP) held on 24-28 Jun. 1991 are included. Viewgraphs from the presentations are included

A Review of Similitude Methods for Structural Engineering

Similitude theory allows, through a set of tools known as similitude methods, to establish the conditions to design a scaled (up or down) model of a full-scale structure, usually defined as prototype. In the last years, to overcome the problems associated with full-scale testing, such as costs and setup, research on similitude methods has grown and their application has expanded in many branches of engineering. The aim of this paper is to provide a review as comprehensive as possible about similitude methods applied to structural engineering; after a brief historical introduction and a more deep analysis of the main methods, the article focuses on the applications classified by test articles

Space exploration: The interstellar goal and Titan demonstration

Automated interstellar space exploration is reviewed. The Titan demonstration mission is discussed. Remote sensing and automated modeling are considered. Nuclear electric propulsion, main orbiting spacecraft, lander/rover, subsatellites, atmospheric probes, powered air vehicles, and a surface science network comprise mission component concepts. Machine, intelligence in space exploration is discussed