Optimal impact angle guidance for exo-atmospheric interception utilizing gravitational effect

This paper aims to develop a new optimal intercept angle guidance law for exo-atmospheric interception by utilizing gravity. A finite-time optimal regulation problem is formulated by considering the instantaneous zero-effort-miss (ZEM) and the intercept angle error as the system states. The analytical guidance command is then derived based on Schwarz's inequality approach and Lagrange multiplier concept. Capturability analysis using instantaneous linear time-invariant system concept is also presented to provide better insights of the proposed guidance law. Theoretical analysis reveals that the proposed optimal guidance law encompasses previously suggested optimal impact angle constrained guidance laws. Numerical simulations with some comparisons clearly demonstrate the effectiveness of the proposed guidance law

Advanced Centaur explicit guidance equation study Final report

Generalized equations and in-flight computer requirements for Centaur guidance and control and advanced mission plannin

An improvement in three-dimensional pure proportional navigation guidance

This paper proposes an improved version of 3D pure proportional navigation (PPN) against a manoeuvring target. The main research hypothesis is that the performance of 3D PPN can be improved by properly selecting the direction of the guidance command as there exists an infinite number of potential directions complying with the PPN concept in 3D space. Analysis on the relative motion confirms the validity of the hypothesis and leads to the development of a new guidance algorithm. Unlike traditional 3D PPN, the guidance algorithm developed adapts the direction, but maintains the magnitude of the commanded acceleration proportional to only the line-of-sight (LOS) rate. The validity and performance of the proposed guidance algorithm are investigated through theoretical analysis and numerical simulations

An Innovative Solution to NASA's NEO Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development

This final technical report describes the results of a NASA Innovative Advanced Concept (NIAC) Phase 2 study entitled "An Innovative Solution to NASA's NEO Impact Threat Mitigation Grand Challenge and Flight Validation Mission Architecture Development." This NIAC Phase 2 study was conducted at the Asteroid Deflection Research Center (ADRC) of Iowa State University in 2012-2014. The study objective was to develop an innovative yet practically implementable solution to the most probable impact threat of an asteroid or comet with short warning time (less than 5 years). The technical materials contained in this final report are based on numerous technical papers, which have been previously published by the project team of the NIAC Phase 1 and 2 studies during the past three years. Those technical papers as well as a NIAC Phase 2 Executive Summary report can be downloaded from the ADRC website (www.adrc.iastate.edu)

Online trajectory replan for gliding vehicle considering terminal velocity constraint

Controlling the terminal velocity can improve the effectiveness of guided missiles. In particular, a ballistic missile propelled by solid rocket motors can successfully accomplish its mission when it hits the target at an appropriate speed. In this study, a method for modifying the trajectory of gliding vehicle, i.e., gliding ballistic missiles is proposed to meet the terminal velocity constraint by reflecting the effects of the environment during a flight. The proposed framework consisting of trajectory generation and dynamic propagation compensates for errors due to uncertainties in real time. The trajectory generation step provides various trajectories that satisfy the given constraints based on information about the current state. The dynamic propagation step efficiently predicts the terminal velocity for each of the generated trajectories and finds the trajectory with the lowest terminal speed error. A numerical simulation is performed considering various conditions to demonstrate the performance of the proposed method

Exoatmospheric Plowshares: Using a Nuclear Explosive Device for Planetary Defense Against an Incoming Asteroid

What should be done if we suddenly discover a large asteroid on a collision course with Earth? The consequences of an impact could be enormous—scientists believe that such a strike 60 million years ago led to the extinction of the dinosaurs, and something of similar magnitude could happen again. Although no such extraterrestrial threat now looms on the horizon, astronomers concede that they cannot detect all the potentially hazardous “near-Earth objects,” and even more striking, they acknowledge that if such a danger were discerned, there is currently no proven capability for diverting or destroying it. One possible response to this type of incipient catastrophe could be to send into space a nuclear explosive device, hoping the massive blast could alter the asteroid\u27s trajectory. Indeed, if time were short, that might be the only effective remedy. But two major nuclear arms control treaties-which have been joined by most of the leading countries and are widely appreciated as fundamental to global security-specifically forbid that approach. This Article examines that critical clash of legal, political, and technical values, and concludes that the best response would be for the UN Security Council to adopt a binding resolution pursuant to its powers under Chapter VII of the UN Charter, to deal with the emergency on an expeditious, global basis. A proposed draft of such a resolution is presented, along with explanatory annotations

MX Missile Basing

A study by the Office of Technology Assessment (OTA) that examines a new intercontinental ballistic missile known as the MX, identifies MX basing modes and assesses "the major advantages, disadvantages, risks, and uncertainties of each" (p. 3)

An Inference about Interference: A Surprising Application of Existing International Law to Inhibit Anti-Satellite Weapons

This article presents a thesis that most readers will find surprising, in an effort to develop a novel, simultaneous solution to three urgent, complex problems related to outer space. The three problems are: a) the technical fact that debris in outer space (the accumulated orbital junk produced by decades of space activities) has grown to present a serious hazard to safe and effective exploration and exploitation of space; b) the strategic fact that many countries (notably the United States, China and Russia, but others, too) continue to demonstrate a misguided interest in pursuing anti-satellite weapons, which can jeopardize the security of space; and c) the political fact that attempts to provide additional legal regulation of outer space (via new bilateral or multilateral international agreements) have failed, with little prospect for prompt conclusion of meaningful new accords. The proposed solution is to adapt existing international law in an unforeseen way. Specifically, numerous current and historical arms control treaties provide for verification of parties’ compliance via “national technical means” (NTM) of verification, which prominently include satellite-based sensory and communications systems. These treaties routinely provide protection for those essential space assets by requiring parties to undertake “not to interfere” with NTM. The argument developed here is that additional tests in space of debris-creating anti-satellite weapons would already be illegal, even without the conclusion of any dedicated new treaty against further weaponization of space, because in the current crowded conditions of space, a new cloud of orbital debris would, sooner or later, impermissibly interfere with NTM satellites. If sustained, this thesis can provide a new rationale for opposition to the development, testing, and use of anti-satellite weapons. It a legal reinforcement for the political instincts to avoid activities that further undercut the optimal usability of outer space, and it demonstrates how creative re-interpretation of existing legal provisions can promote the advancement of the rule of international law, even in circumstances where the articulation of new treaties is blocked