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This paper presents trajectory reconstruction of the ST-9 (space technology) sounding rocket experiment using the onboard inertial measurement unit data and descent imagery. The raw inertial measurement unit accelerometer measurements are first converted into inertial acceleration and then used in trajectory integration. The descent images are preprocessed using a map-matching algorithm and unique landmarks for each image are created. Using the converted inertial measurement unit data and descent images, the result from dead-reckoning and the kinematic-fix approaches are first compared with the global positioning system measurements. Then, both the inertial measurement unit data and landmarks are processed together using a batch least-squares filter and the position, velocity, stochastic acceleration, and camera orientation of each image are estimated. The reconstructed trajectory is compared with the global positioning system data and the corresponding formal uncertainties are presented. The result shows that inertial measurement unit data and descent images processed with a batch filter algorithm provide the trajectory accuracy required for pinpoint landing. [ABSTRACT FROM AUTHOR]

Onboard optical-based autonomous navigation (autonav) has the potential to significantly reduce reliance on ground-based assets, and it can provide a robust backup system for unexpected ground outages. An investigation of autonav across the solar system is continued here by assessing optical-only navigation performance in cislunar space using simulated observations of the center of the moon, lunar landmarks, artificial satellites, and asteroids. It is shown that autonav in cislunar space is feasible and effective within current technological capabilities, and that artificial satellites, the moon center, and lunar landmarks are effective targets for navigation in this region. [ABSTRACT FROM AUTHOR]

NASA's Deep Space 1 mission demonstrated that a spacecraft can be navigated autonomously during deep-space cruise operations using only optical navigation measurements. A methodology is developed to evaluate the feasibility and accuracy of the Deep Space 1 orbit determination approach throughout the solar system as a function of a spacecraft's imaging capabilities. Feasibility can be addressed by comparing the apparent magnitudes of the known population of asteroids against the imaging system capabilities. An upper limit on the accuracy of the spacecraft position estimate at a given location can be formulated by assuming observations of at least two asteroids simultaneously. Example results are presented for three camera implementations that span the range of capabilities flown in deep space to date using orbit and absolute magnitude data for 50,129 of the brightest known asteroids. Broadly speaking, achievable accuracies range from approximately 200 to 12,000 km (1-σ) interior to the main asteroid belt and from 50 to 2000 km within the main belt, depending strongly on the chosen camera implementation. Between the main belt and Jupiter, only a current state-of-the-art imaging system is consistently capable of kinematic positioning using only asteroids. Beyond Jupiter, there are insufficient known asteroids to support this approach without including images of planets and moons. Although these levels of accuracy are far inferior to those achievable with radiometric navigation, they may yet be sufficient to satisfy cruise-phase requirements for many deep-space missions. [ABSTRACT FROM AUTHOR]

Large navigation and atmospheric uncertainties have historically driven the need for a mid-lift-to-drag-ratio (mid-L/D) vehicle with (L/D)max of 0.6-0.8 for aerocapture at Neptune. Most planetary entry vehicles flown to date are low-L/D blunt-body aeroshells with L/D less than 0.4. The lack of a heritage mid-L/D aeroshell presents a major hurdle for Neptune aerocapture, as the development of a new entry vehicle incurs significant time and investment. Techniques that may allow Neptune aerocapture to be feasible using heritage low-L/D blunt-body aeroshells are investigated that obviate the need for mid-L/D aeroshells. A navigation study is performed to quantify the delivery errors, and a new guidance algorithm with onboard density estimation is developed to accommodate large atmospheric uncertainties. Monte Carlo simulation results indicate that the reduced navigation uncertainty and improved guidance scheme enable a blunt-body aeroshell with L/D=0.3-0.4 to perform aerocapture at Neptune. The expected heat rate is within the capabilities of existing thermal protection system materials. [ABSTRACT FROM AUTHOR]