Monte Carlo Simulations of the Formation Flying Dynamics for the Magnetospheric Multiscale (MMS) Mission

The MMS mission is an ambitious space physics mission that will fly 4 spacecraft in a tetrahedron formation in a series of highly elliptical orbits in order to study magnetic reconnection in the Earth's magnetosphere. The mission design is comprised of a combination of deterministic orbit adjust and random maintenance maneuvers distributed over the 2.5 year mission life. Formal verification of the requirements is achieved by analysis through the use of the End-to-End (ETE) code, which is a modular simulation of the maneuver operations over the entire mission duration. Error models for navigation accuracy (knowledge) and maneuver execution (control) are incorporated to realistically simulate the possible maneuver scenarios that might be realized These error models, coupled with the complex formation flying physics, lead to non-trivial effects that must be taken into account by the ETE automation. Using the ETE code, the MMS Flight Dynamics team was able to demonstrate that the current mission design satisfies the mission requirements

Modeling Extended Fluid Objects in General Relativity

The purpose of this dissertation is to introduce and explore the notion of modeling extended fluid objects in numerical general relativity. These extended fluid objects, called Fat Particles, are proxies for compact hydrodynamic objects. Unlike full hydrodynamic models, we make the approximation that the details of the matter distribution are not as important as the gross motion of the Fat Particle's center of mass and its contribution to the gravitational field. Thus we provide a semi-analytic model of matter for numerical simulations of Einstein's equations, which may help in modeling gravitational radiation from candidate sources. Our approach to carrying out these investigations is to begin with a continuum variational principle, which yields the desired hydrodynamic and gravitational equations for ideal fluids. Following our analysis of the related numerical technique, Smoothed Particle Hydrodynamics (SPH), we apply a set of discretization and smoothing rules to obtain a discrete action. Subsequent variations yield the Fat Particle equations. Our analysis of a classical ideal fluid demonstrated that a Newtonian Fat Particle is capable of remaining at rest while generating its own gravitational field. We then developed analogous principles for describing relativistic ideal fluids in both covariant and ADM 3+1 forms. Using these principles, we developed analytic and numerical results from relativistic Fat Particle theory. We began with the Subscribe Only model, in which a Fat Particle of negligible mass moves in a fixed background metric. Corrections to its motion due to the extended nature of the Fat Particle, are obtained by summing metric contributions over its volume. We find a universal scaling law that describes the phase shift, relative to a test particle, that is independent of its size, shape, and distribution. We then show that finite-size effects eventually dominate radiation damping effects in describing the motion of a white dwarf around a more massive black hole. Finally, we derive the Publish and Subscribe model, which comprises a full back-reacting system. Comparison of the Fat Particle equations for a static, symmetric spacetime with their continuum analogs shows that the system supports a consistent density definition and holds promise for future development

Magnetospheric MultiScale Mission (MMS) Overview

The MMS mission was launched on March 13, 2015 aboard an Atlas V rocket from Space Launch Complex 40, Cape Canaveral, Florida Each of the four observatories were successfully released at five minute intervals spinning at 3 rpm approximately 1.5 hours after launch

Operational Experiences in Planning and Reconstructing Aqua Inclination Maneuvers

ABSTRACT As the lead satellite in NASA's growing Earth Observing System (EOS) PM constellation, it is increasingly critical that Aqua maintain its various orbit requirements. The two of interest for this paper are maintaining an orbit inclination that provides for a consistent mean local time and a semi-major Axis (SMA) that allows for ground track repeatability. Maneuvers to adjust the orbit inclination involve several flight dynamics constraints and complexities which make planning such maneuvers challenging. In particular, coupling between the orbital and attitude degrees of freedom lead to changes in SMA when changes in inclination are effected. A long term mission mean local time trend analysis was performed in order to determine the size and placement of the required inclination maneuvers. Following this analysis, detailed modeling of each burn and its various segments was performed to determine its effects on the immediate orbit state. Data gathered from an inclination slew test of the spacecraft and first inclination maneuver uncovered discrepancies in the modeling method that were investigated and resolved. The new modeling techniques were applied and validated during the second spacecraft inclination maneuver. These improvements should position Aqua to successfully complete a series of inclination maneuvers in the fall of 2004. The following paper presents the events and results related to the first two Aqua inclination maneuvers

Magnetospheric MultiScale (MMS) System Manager

The Magnetospheric MultiScale (MMS) mission is an ambitious NASA space science mission in which 4 spacecraft are flown in tight formation about a highly elliptical orbit. Each spacecraft has multiple instruments that measure particle and field compositions in the Earths magnetosphere. By controlling the members relative motion, MMS can distinguish temporal and spatial fluctuations in a way that a single spacecraft cannot.To achieve this control, 2 sets of four maneuvers, distributed evenly across the spacecraft must be performed approximately every 14 days. Performing a single maneuver on an individual spacecraft is usually labor intensive and the complexity becomes clearly increases with four. As a result, the MMS flight dynamics team turned to the System Manager to put the routine or error-prone under machine control freeing the analysts for activities that require human judgment.The System Manager is an expert system that is capable of handling operations activities associated with performing MMS maneuvers. As an expert system, it can work off a known schedule, launching jobs based on a one-time occurrence or on a set reoccurring schedule. It is also able to detect situational changes and use event-driven programming to change schedules, adapt activities, or call for help

MMS observations of storm‐time magnetopause boundary layers in the vicinity of the Southern cusp

80MSFC20C0019 - NASAPublished versio

Energy Partitioning Constraints at Kinetic Scales in Low- Turbulence

Turbulence is a fundamental physical process through which energy injected into a system at large scales cascades to smaller scales. In collisionless plasmas, turbulence provides a critical mechanism for dissipating electromagnetic energy. Here we present observations of plasma fluctuations in low- turbulence using data from NASAs Magnetospheric Multiscale mission in Earths magnetosheath. We provide constraints on the partitioning of turbulent energy density in the fluid, ion-kinetic, and electron-kinetic ranges. Magnetic field fluctuations dominated the energy density spectrum throughout the fluid and ion-kinetic ranges, consistent with previous observations of turbulence in similar plasma regimes. However, at scales shorter than the electron inertial length, fluctuation power in electron kinetic energy significantly exceeded that of the magnetic field, resulting in an electron-motion-regulated cascade at small scales. This dominance should be highly relevant for the study of turbulence in highly magnetized laboratory and astrophysical plasmas

Phase I/pharmacokinetic study of CCI-779 in patients with recurrent malignant glioma on enzyme-inducing antiepileptic drugs

Objectives : CCI-779 is an ester of the immunosuppressive agent sirolimus (rapamycin) that causes cell-cycle arrest at G1 via inhibition of key signaling pathways resulting in inhibition of RNA translation. Antitumor activity has been demonstrated using cell lines and animal models of malignant glioma. Patients receiving enzyme-inducing anti-epileptic drugs (EIAEDs) can have altered metabolism of drugs like CCI-779 that are metabolized through the hepatic cytochrome P450 enzyme system. The objectives of this study were to determine the pharmacokinetic profile and the maximum tolerated dose of CCI-779 in patients with recurrent malignant gliioma taking EIAEDs. Study design: The starting dose of CCI-779 was 250 mg intravenously (IV) administered weekly on a continuous basis. Standard dose escalation was performed until the maximum tolerated dose was established. Toxicity was assessed using the National Cancer Institute common toxicity criteria. Results : Two of 6 patients treated at the second dose level of 330 mg sustained a dose-limiting toxicity: grade III stomatitis, grade 3 hypercholesterolemia, or grade 4 hypertriglyceridemia. The maximum tolerated dose was reached at 250 mg IV. Pharmacokinetic profiles were similar to those previously described, but the area under the whole blood concentration-time curve of rapamycin was 1.6 fold lower for patients on EIAEDs. Conclusions : The recommended phase II dose of CCI 779 for patients on enzyme-inducing antiepileptic drugs is 250 mg IV weekly. A phase II study is ongoing to determine the efficacy of this agent.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45250/1/10637_2004_Article_5273867.pd

Origin and temporal variability of unusually low δ13C-DOC values in two High Arctic catchments

The stable carbon isotopic composition of dissolved organic matter (δ13C-DOC) reveals information about its source and extent of biological processing. Here we report the lowest δ13C-DOC values (−43.8‰) measured to date in surface waters. The streams were located in the High Arctic, a region currently experiencing rapid changes in climate and carbon cycling. Based on the widespread occurrence of methane cycling in permafrost regions and the detection of the pmoA gene, a proxy for aerobic methanotrophs we conclude that the low δ13C-DOC values are due to organic matter partially derived from methanotrophs consuming biologically produced, 13C-depleted methane. These findings demonstrate the significant impact that biological activity has on the stream water chemistry exported from permafrost and glaciated environments in the Arctic. Given that the catchments studied here are representative of larger areas of the Arctic, occurrences of low δ13C-DOC values may be more widespread than previously recognized, with implications for understanding C cycling in these environments.Publisher PDFPeer reviewe

Phase II study of CCI-779 in patients with recurrent glioblastoma multiforme

Purpose : Loss of PTEN, which is common in glioblastoma multiforme (GBM), results in activation of the mammalian target of rapapmycin (mTOR), thereby increasing mRNA translation of a number of key proteins required for cell-cycle progression. CCI-779 is an inhibitor of mTOR. The primary objectives of this study were to determine the efficacy of CCI-779 in patients with recurrent GBM and to further assess the toxicity of the drug. Experimental Design : CCI-779 was administered weekly at a dose of 250 mg intravenously for patients on enzyme-inducing anti-epileptic drugs (EIAEDs). Patients not on EIAEDs were initially treated at 250 mg; however, the dose was reduced to 170 mg because of intolerable side effects. Treatment was continued until unacceptable toxicity, tumor progression, or patient withdrawal. The primary endpoint was 6-month progression-free survival. Results : Forty-three patients were enrolled; 29 were not on EIAEDs. The expected toxicity profile of increased lipids, lymphopenia, and stomatitis was seen. There were no grade IV hematological toxicities and no toxic deaths. One patient was progression free at 6 months. Of the patients assessable for response, there were 2 partial responses and 20 with stabilization of disease. The median time to progression was 9 weeks. Conclusions : CCI-779 was well tolerated at this dose schedule; however, there was no evidence of efficacy in patients with recurrent GBM. Despite initial disease stabilization in approximately 50% of patients, the durability of response was short. Because of the low toxicity profile, CCI-779 may merit exploration in combination with other modalities.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45273/1/10637_2005_Article_1444.pd