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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

SEDS: The Spitzer Extended Deep Survey. Survey Design, Photometry, and Deep IRAC Source Counts

The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46 deg(exp 2) to a depth of 26 AB mag (3sigma) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5 micron. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z = 2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six-month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300,000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6 +/- 1.0 and 4.4 +/- 0.8 nW / square m/sr at 3.6 and 4.5 micron to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.

Spitzer↗
NASA NTRS1999

The Future of the Deep Space Network: Technology Development for K2-Band Deep Space Communications

Projections indicate that in the future the number of NASA's robotic deep space missions is likely to increase significantly. A launch rate of up to 4-6 launches per year is projected with up to 25 simultaneous missions active [I]. Future high resolution mapping missions to other planetary bodies as well as other experiments are likely to require increased downlink capacity. These future deep space communications requirements will, according to baseline loading analysis, exceed the capacity of NASA's Deep Space Network in its present form. There are essentially two approaches for increasing the channel capacity of the Deep Space Network. Given the near-optimum performance of the network at the two deep space communications bands, S-Band (uplink 2.025-2.120 GHz, downlink 2.2-2.3 GHz), and X-Band (uplink 7.145-7.19 GHz, downlink 8.48.5 GHz), additional improvements bring only marginal return for the investment. Thus the only way to increase channel capacity is simply to construct more antennas, receivers, transmitters and other hardware. This approach is relatively low-risk but involves increasing both the number of assets in the network and operational costs.

Bhanji, Alaudin M.↗
NASA NTRS2020

Results of the Deep Space Atomic Clock Deep Space Navigation Analog Experiment

The timing and frequency stability provided by the Deep Space Atomic Clock (DSAC) is almost comparable with the Deep Space Network’s ground clocks, and will enable one-way radiometric measurements with accuracy equivalent to cur- rent two-way tracking data. A demonstration unit of the clock was launched into low Earth orbit on June 25, 2019, for the purpose of validating DSAC’s perfor- mance in the space environment. GPS data collected throughout the mission was utilized not only for precise clock estimation, but also as a proxy for deep space tracking data to conduct the Deep Space Navigation Analog Experiment. Through careful processing of GPS Doppler data and limited modeling fidelity representa- tive of deep space navigation capabilities, the analog orbit solutions are compared to higher-fidelity solutions, demonstrating DSAC’s viability as a navigation instru- ment in conditions typical for a low altitude Mars orbiter.

Stuart, Jeffrey↗
NASA NTRS2021

Scheduling the NASA Deep Space Network with Deep Reinforcement Learning

With three complexes spread evenly across the Earth, NASA’s Deep Space Network (DSN) is the primary means of communications as well as a significant scientific instrument for dozens of active missions around the world. A rapidly rising number of spacecraft and increasingly complex scientific instruments with higher bandwidth requirements have resulted in demand that exceeds the network’s capacity across its 12 antennae. The existing DSN scheduling process operates on a rolling weekly basis and is time-consuming; for a given week, generation of the final baseline schedule of spacecraft tracking passes takes roughly 5 months from the initial requirements submission deadline, with several weeks of peer-to-peer negotiations in between. This paper proposes a deep reinforcement learning (RL) approach to generate candidate DSN schedules from mission requests and spacecraft ephemeris data with demonstrated capability to address real-world operational constraints. A deep RL agent is developed that takes mission requests for a given week as input, and interacts with a DSN scheduling environment to allocate tracks such that its reward signal is maximized. A comparison is made between an agent trained using Proximal Policy Optimization and its random, untrained counterpart. The results represent a proof-of-concept that, given a well-shaped reward signal, a deep RL agent can learn the complex heuristics used by experts to schedule the DSN. A trained agent can potentially be used to generate candidate schedules to bootstrap the scheduling process and thus reduce the turnaround cycle for DSN scheduling.

Wilson, Brian↗
NASA NTRS1981

Radio frequency interference protection of communications between the Deep Space Network and deep space flight projects

The increasing density of electrical and electronic circuits in Deep Space Station systems for computation, control, and numerous related functions has combined with the extension of system performance requirements calling for higher speed circuitry along with broader bandwidths. This has progressively increased the number of potential sources of radio frequency interference inside the stations. Also, the extension of spectrum usage both in power and frequency as well as the greater density of usage at all frequencies for national and international satellite communications, space research, Earth resource operations and defense, and particularly the huge expansion of airborne electronic warfare and electronic countermeasures operations in the Mojave area have greatly increased the potential number and severity of radio frequency interference incidents. The various facets of this problem and the efforts to eliminate or minimize the impact of interference on Deep Space Network support of deep space flight projects are described.

Johnston, D. W. H.↗
NASA NTRS2022

Enabling a Larger Deep Space Mission Suite: A Deep Space Network Queuing Antenna for Demand Access

The advent of deep space small spacecraft, as exemplified by the Mars Cubesat One (MarCO), Lunar Trailblazer, Janus, the Escape and Plasma Acceleration and Dynamics Explorers (EscaPADE), and the thirteen Artemis 1 missions, opens the possibility that a much larger number of deep space spacecraft may be launched over the next 10 years and beyond. While scientifically exciting, the prospect of a (much) larger mission suite raises significant challenges for the current approach to ground stations and mission operations. We have been investigating an integrated approach for ground stations and missions operations to enable new modes of operation while maintaining the capabilities of the current operational techniques. This integrated approach is built around three core capabilities: (1) A queuing antenna that enables monitoring the status of a much larger number of spacecraft, and allows spacecraft to transmit requests for telemetry with NASA’s Deep Space Network (DSN); (2) a flexible scheduling system that expands the current DSN scheduling services to enable allocating time on DSN antennas in near real-time; and (3) a cloud-based ground data system that can be spun up and down according to how tracks are assigned by the flexible scheduling system. We shall show that an 18 meter DSN queuing antenna equipped with cyrogenic receivers would enable use of the DSN Demand Access Service for small spacecraft throughout the inner Solar System, thus providing service to a large mission suite. We first discuss the architecture of the queuing antenna and its supporting systems, including, for instance, the service required to generate the schedule for the queueing antenna (which dictates how it slews to monitor multiple spacecraft in a day of operations). Next, we describe the signaling scheme used to encode a request, which is inherited from the already operational DSN Beacon Tone Service, and describe two alternative ways to detect the incoming tone at the ground station, one based on maximum likelihood estimation (MLE), and another one based on Fast-Fourier Transfer (FFT) processing. We then use these results to estimate the maximum range at which a request can be reliably detected as a function of the spacecraft and ground station communication capabilities. Finally, the last part of this part of this paper briefly describes the prototyping effort undertaken at Morehead State University (MSU) and JPL to demonstrate the viability of this new DSN demand access. In particular, we describe the suite of tests conducted using MSU’s 21 meter ground station to validate its use a queuing antenna.

Mattle, Emily↗
NASA NTRS1982

The Deep Space Network. An instrument for radio navigation of deep space probes

The Deep Space Network (DSN) network configurations used to generate the navigation observables and the basic process of deep space spacecraft navigation, from data generation through flight path determination and correction are described. Special emphasis is placed on the DSN Systems which generate the navigation data: the DSN Tracking and VLBI Systems. In addition, auxiliary navigational support functions are described.

Renzetti, N. A.↗
NASA NTRS1983

The Deep Space Network: A Radio Communications Instrument for Deep Space Exploration

The primary purpose of the Deep Space Network (DSN) is to serve as a communications instrument for deep space exploration, providing communications between the spacecraft and the ground facilities. The uplink communications channel provides instructions or commands to the spacecraft. The downlink communications channel provides command verification and spacecraft engineering and science instrument payload data.

Renzetti, N. A.↗
NASA NTRS1991

Interference prediction for deep space spacecraft from ground stations - Interference to the Galileo deep space spacecraft from the GOMS geostationary network

A technique for predicting the interference power spectral density from a ground station to a spacecraft in deep space is described. The interference prediction throughout the complete mission is simulated, and distance between the ground station and the deep space spacecraft is calculated. A power spectral density from the GOMS satellite network to the Galileo spacecraft receiver is computed using the thermal noise density level at the Galileo spacecraft as the interference criterion. Data obtained indicate that all three GOMS stations cause at least 30 minutes of interference during Galileo earth flyby number one, and two GOMS ground stations cause at least four minutes of interference during Galileo earth flyby number.

Bishop, Dennis F.↗
NASA NTRS2012

Preliminary Results of a U.S. Deep South Warm Season Deep Convective Initiation Modeling Experiment using NASA SPoRT Initialization Datasets for Operational National Weather Service Local Model Runs

The initiation of deep convection during the warm season is a forecast challenge in the relative high instability and low wind shear environment of the U.S. Deep South. Despite improved knowledge of the character of well known mesoscale features such as local sea-, bay- and land-breezes, observations show the evolution of these features fall well short in fully describing the location of first initiates. A joint collaborative modeling effort among the NWS offices in Mobile, AL, and Houston, TX, and NASA s Short-term Prediction Research and Transition (SPoRT) Center was undertaken during the 2012 warm season to examine the impact of certain NASA produced products on the Weather Research and Forecasting Environmental Modeling System. The NASA products were: a 4-km Land Information System data, a 1-km sea surface temperature analysis, and a 4-km greenness vegetation fraction analysis. Similar domains were established over the southeast Texas and Alabama coastlines, each with a 9 km outer grid spacing and a 3 km inner nest spacing. The model was run at each NWS office once per day out to 24 hours from 0600 UTC, using the NCEP Global Forecast System for initial and boundary conditions. Control runs without the NASA products were made at the NASA SPoRT Center. The NCAR Model Evaluation Tools verification package was used to evaluate both the forecast timing and location of the first initiates, with a focus on the impacts of the NASA products on the model forecasts. Select case studies will be presented to highlight the influence of the products.

Medlin, Jeffrey M.↗
NASA NTRS1997

Deep Space One: NASA's First Deep-Space Technology Validation Mission

Under development for launch in July 1998, Deep Space One (DS1) is the first flight of NASA's New Millennium Program, Chartered to validate selected technologies required for future low-cost space science programs. Advanced technologies chosen for validation on DS1 include solar electric propulsion, high-power solar concentrator arrays, autonomous on-board optical navigation, two low-mass science instrument packages, and several telecommunications and microelectronics devices.

Deep↗
NASA NTRS2000

Microbial Life in the Deep Subsurface: Deep, Hot and Radioactive

Recent studies, motivated in part by the search for extraterrestrial life, continue to expand the recognized limits of Earth's biosphere. This work explored evidence for life a high-temperature, radioactive environment in the deep subsurface.

DeStefano, Andrea L.↗
NASA NTRS1997

A Deep Imaging Survey of NGC 6475 and a Deep Survey of the Young Open Cluster Alpha Persei

We have published three papers directly related to the x-ray data (see below), and one other paper directly related to the optical photometry obtained in connection to the ROSAT data analysis (also listed below). In addition, we have used the x-ray data in combination with the optical photometry and with high resolution optical spectra that we have obtained (to derive spectroscopic rotational velocities) to address questions related to the dependence of coronal activity on the rotation rate, mass, and other characteristics of the target stars. The overall goal of our ROSAT projects has been to determine the time evolution of coronal activity in low mass stars, and from that behavior place constraints on the physical processes involved in generating coronal activity. NGC 6475 and Alpha Persei are important parts of that process. We are now beginning to address how these data constrain theoretical models of angular momentum evolution and dynamo magnetic field generation (see paper by Stauffer et al. and Krishnamurthi et al. listed below in the "related papers" section). We are still working on two papers pertaining to this grant (rotational velocities and chromospheric activity of Alpha Persei x-ray sources and rotational velocities and lithium abundances of NGC 6475 sources), but we will publish those papers using funds from other grants.

Stauffer, John R.↗
NASA NTRS2000

Environmental Effects on Volcanic Eruptions:From Deep Ocean to Deep Space. Chapter 3. Volcanism and Ice Interactions on Earth and Mars

CONCLUSION Volcano/ice interactions produce meltwater. Meltwater can enter the groundwater cycle and under the influence of hydrothermal systems, it can be later discharged to form channels and valleys or cycled upward to melt permafrost. Water or ice-saturated ground can erupt into phreatic craters when covered by lava. Violent mixing of meltwater and volcanic material and rapid release can generate lahars or jokulhlaups, that have the ability to freight coarse material, great distances downslope from the vent. Eruption into meltwater generate unique appearing edifices, that are definitive indicators of volcano/ice interaction. These features are hyaloclastic ridges or mounds and if capped by lava, tuyas. On Earth, volcano/ice interactions are limited to alpine regions and ice-capped polar and temperate regions. On Mars, where precipitation may be an ancient phenomenon, these interactions may be limited to areas of ground ice accumulation or the northern lowlands where water may have ponded fairly late in martian history. The recognition of features caused by volcano/ice interactions could provide strong constraints for the history of volatiles on Mars.

Chapman, Mary G.↗