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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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NASA NTRS1991

The Advanced Receiver II telemetry test results at Goldstone

The telemetry performance of the Advanced Receiver II (ARX-II) in tracking and demodulating signals from various deep space missions is described. The tests were performed at Goldstone, and the spacecrafts tracked were Pioneer 10, Pioneer 11, Voyager 2, Magellan, and the International Cometary Explorer (ICE). These missions present a broad range of operating conditions to test the ARX-II in terms of signal-to-noise ratio (SNR) and the symbol rate of the received signal.

Sadr, R.↗

NASA NTRS1992

Determining maintenance cost ratios

This paper reports on the wide range of costs involved in maintaining equipment and discusses methods that different industries use to measure and report their maintenance cost. Results are presented of the study of maintenance costs in the NASA Deep Space Network (DSN) and of a comparison of DSN maintenance cost with the maintenance costs of a number of other reports. A comparison of the maintenance costs in terms of the maintenance cost ratio (annual maintenance cost/capital replacement cost) shows that DSN has the lowest maintenance cost ratio of the industries and organizations surveyed.

Remer, Donald S.↗

NASA NTRS1993

An overview of the Galileo Optical Experiment (GOPEX)

Uplink optical communication to a deep-space vehicle was demonstrated. In the Galileo Optical Experiment (GOPEX), optical transmissions were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The demonstration took place over an eight-day period (9 Dec. through 16 Dec. 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1-6 million km. At 6 million km (15 times the Earth-Moon distance), the laser beam transmitted from TMF eight days after Earth flyby covered the longest known range for transmission and detection.

Wilson, K. E.↗

NASA NTRS1999

Thermal Environmental Testing of NSTAR Engineering Model Ion Thrusters

NASA's New Millenium program will fly a xenon ion propulsion system on the Deep Space 1 Mission. Tests were conducted under NASA's Solar Electric Propulsion Technology Applications Readiness (NSTAR) Program with 3 different engineering model ion thrusters to determine thruster thermal characteristics over the NSTAR operating range in a variety of thermal environments. A liquid nitrogen-cooled shroud was used to cold-soak the thruster to -120 C. Initial tests were performed prior to a mature spacecraft design. Those results and the final, severe, requirements mandated by the spacecraft led to several changes to the basic thermal design. These changes were incorporated into a final design and tested over a wide range of environmental conditions.

Rawlin, Vincent K.↗

NASA NTRS2004

Europa's Icy Shell: A Bridge Between Its Surface and Ocean

Europa, a Moon-sized, ice-covered satellite of Jupiter, is second only to Mars in its astrobiological potential. Beneath the icy surface, an ocean up to 150 km deep is thought to exist, providing a potential habitat for life,and a tempting target for future space missions. The Galileo mission to the Jovian system recently ended, but there are already long-range plans to send much more capable spacecraft,such as the proposed Jupiter Icy Moons Orbiter (JIMO), to take a closer look at Europa and her siblings, Ganymede and Callisto, some time in the next two decades. Europak outer icy shell is the only interface between this putative ocean and the surface, but many aspects of this shell are presently poorly understood; in particular, its composition, thickness, deformational history, and mechanical properties. To discuss the ice shell and our current understanding of it, 78 scientists from the terrestrial and planetary science communities in the United States and Europe gathered for a 3-day workshop hosted by the Lunar and Planetary Institute in Houston in February. A key goal was to bring researchers from disparate disciplines together to discuss the importance and limitations of available data on Europa with a post-Galileo perspective. The workshop featured 2 days of reviews and contributed talks on the composition, physical properties, stratigraphy, tectonics, and future exploration of the ice shell and underlying ocean. The final morning included an extended discussion period, moderated by a panel of noted experts, highlighting outstanding questions and areas requiring future research.

Schenk, Paul↗

NASA NTRS2021

Mars 2020 Perseverance trajectory reconstruction and performance from launch through landing

The Mars 2020 (M2020) Mission carrying Perseverance, the most advanced rover ever sent to Mars, successfully launched on an Atlas V 541 (AV-088) launch vehicle from the Eastern Test Range (ETR) at Cape Canaveral Air Force Station (CCAFS) in Florida at 11:50:00 UTC (T-Zero time) on July 30, 2020. After some station reconfiguration, carrier/telemetry were locked at both Deep Space Network (DSN) Canberra and Goldstone stations. Perseverance entered the Martian atmosphere at 20:36:50 Spacecraft Event Time (SCET) UTC, and landed inside Jezero Crater at 20:43:49 SCET UTC on February 18, 2021. Confirmation of nominal landing was received at the DSN Goldstone and Madrid tracking stations via the Mars Reconnaissance Orbiter at 20:55:11 Earth Received Time (ERT) UTC. This paper summarizes in detail the actual vs. predicted performance in terms of launch vehicle events, launch vehicle injection performance, actual DSN spacecraft lockup, trajectory correction maneuver performance, Entry, Descent, and Landing events, and overall trajectory and geometric characteristics.

Abilleira, Fernando↗

NASA NTRSDate not supplied

Maneuver Reconstruction, Tracking Scheduling, and Bias Estimation in the Near Rectilinear Halo Orbit (NRHO)

NASA’s Gateway program will build a crew-tended station in an Earth-Moon Near Rectilinear Halo Orbit (NRHO) to support deep space missions to the lunar surface and heliocentric space. The station in the NRHO will be tracked by the Deep Space Network (DSN) with 2-way radiometric tracking data to produce an estimated state that is utilized to target Orbit Maintenance Maneuvers (OMMs). However, the tracking data is corrupted with measurement noise and range bias, which results in state estimation error and OMM execution error. This paper reports on analysis performed to improve the geometry of the tracking data problem with the inclusion of cross-hemispheric partner sites and explores the performance impact of handovers between partner sites and DSN sites. The OMM execution error is estimated directly using a Batch Least Squares (BLS) process, and the range bias estimation is analyzed among both original DSN sites and a combined DSN + partner sites scenario.

Clark P Newman↗

NASA NTRS2021

Mars 2020 Perseverance Trajectory Reconstruction and Performance from Launch through Landing

Wong, Mau↗

NASA NTRS2004

Spitzer Orbit Determination During In-orbit Checkout Phase

The Spitzer Space Telescope was injected into heliocentric orbit on August 25, 2003 to observe and study astrophysical phenomena in the infrared range of frequencies. The initial 60 days was dedicated to Spitzer's "In-Orbit Checkout (IOC)" efforts. During this time high levels of Helium venting were used to cool down the telescope. Attitude control was done using reaction wheels, which in turn were de-saturated using cold gas Nitrogen thrusting. Dense tracking data (nearly continuous) by the Deep Space network (DSN) were used to perform orbit determination and to assess any possible venting imbalance. Only Doppler data were available for navigation. This paper deals with navigation efforts during the IOC phase. It includes Dust Cover Ejection (DCE) monitoring, orbit determination strategy validation and results and assessment of non-gravitational accelerations acting on Spitzer including that due to possible imbalance in Helium venting.

helium venting↗

NASA NTRS1987

Technological status and future challenges of deep space optical communication

An account is given of the concepts, techniques, and system design features that may be used to realize an optical communications link for future planetary missions. Such a spacecraft subsystem would encompass a 10-30 cm aperture optical telescope for both transmitting and receiving. Uplink from a laser, in the form of pulsed ranging signals or command information, will be extracted by a tracking detector; downlink data, as well as detected ranging pulses, will be properly formatted and used to modulate the downlink laser. The optical receiving station may be either on the ground or in earth orbit.

Lesh, James R.↗

NASA NTRS1988

Long-lived thermal control materials for high temperature and deep space applications

Considerable effort has been put into developing thermal-control materials for the Galileo space-craft. This paper presents a summary of these findings to date with emphasis on requirements, testing and results for the post-Challenger Galileo mission. Polyimide film (Kapton), due to its inherent stability in vacuum, UV, and radiation environments, combined with good mechanical properties over a large temperature range, has been the preferred substrate for spacecraft thermal control materials. Composite outer layers, using Kapton substrates, can be fabricated to meet the requirements of severe space environments. Included in the processing of Kapton-based composite outer layers can be the deposition of metal oxide, metallic and/or polymeric thin-film coatings to provide desirable electrical, optical and thermo-optical properties. In addition, reinforcement of Kapton substrates with fabrics and films is done to improve mechanical properties. Also these substrates can be filled with varying amounts of carbon to achieve particular electrical properties. The investigation and material development reported on here has led to improved thermo-gravimetric stability, surface conductivity, RF transparency, radiation and UV stability, flammability and handle-ability of outer layer thermal control materials for deep space and near-sun spacecraft. Designing, testing, and qualifying composite thermal-control film materials to meet the requirements of the Galileo spacecraft is the scope of this paper.

Whitt, Robin↗

NASA NTRS1991

The role of clocks in operating deep space missions

Operation of deep space missions requires stable frequency references and clocks to perform several mission critical functions. These references are used in generating the telecommunication links to maintain communications between earth and spacecraft, in generating accurate doppler, range, and very long baseline interferometry (VLBI) observables for determining the spacecraft's time varying position, and to generate on-board timing information for clocking out timed commands and time tagging instrument data. In addition, science applications exist, particularly those utilizing radio instrumentation, which can require additional functions and levels of performance. The design necessary to support these functions affects both the spacecraft and the ground tracking stations. This paper provides a brief description of these functions and some of the key requirements needed to support them.

S. W. Asmar↗

NASA NTRS1994

A model for analysis of TDA budget allocation

There is an ever-increasing need to achieve greater efficiency in the operation of the Deep Space Network (DSN), i.e., increased productivity at reduced cost. One of the tools used in the course of a planning workshop on this subject was a methodology for budget allocation applicable to long-range planning. This article presents a model for analysis of the TDA budget allocation. For the 1994 through 1999 period, the percentage of the total TDA budget allocated to capacity and capability is being cut in half, whereas the percentage spent on efficiency of delivery will be increasing.

Remer, D. S.↗

NASA NTRS2003

Coupled Attitude and Orbit Dynamics and Control in Formation Flying Systems

Formation flying systems can range from global constellations offering extended service coverage to clusters of highly coordinated vehicles that perform distributed sensing. Recently, the use of groups of micro-satellites in the areas of near Earth explorations, deep space explorations, and military applications has received considerable attention by researchers and practitioners. To date, most proposed control strategies are based on linear models (e.g., Hill-Clohessy-Wiltshire equations) or nonlinear models that are restricted to circular reference orbits. Also, all models in the literature are uncoupled between relative position and relative attitude. In this paper, a generalized dynamic model is proposed. The reference orbit is not restricted to the circular case. In this formulation, the leader or follower satellite can be in either a circular or an elliptic orbit. In addition to maintaining a specified relative position, the satellites are also required to maintain specified relative attitudes. Thus the model presented couples vehicle attitude and orbit requirements. Orbit perturbations are also included. In particular, the J(sub 2) effects are accounted in the model. Finally, a sliding mode controller is developed and used to control the relative attitude of the formation and the simulation results are presented.

Yunjun Xu↗

NASA NTRS2003

Minimum impulse thruster valve design and development

The design and development of a minimum impulse thruster valve was conducted, by Moog, under contract by NASA's Jet Propulsion Laboratory, California Institute of Technology, for deep space propulsion systems. The effort was focused on applying known solenoid design techniques scaled to provide a 1 -millisecond response capability for monopropellant, hydrazine ACS thruster applications. The valve has an extended operating temperature range of 20(deg)F to +350(deg)F with a total mass of less than 25 grams and nominal power draw of 7 watts. The design solution resulted in providing a solenoid valve that is one-tenth the scale of the standard product line. The valve has the capability of providing a mass flow rate of 0.0009 pounds per second hydrazine. The design life of 1,000,000 cycles was demonstrated both dry and wet. Not all design factors scaled as expected and proved to be the focus of the final development effort. These included the surface interactions, hydrodynamics and driver electronics. The resulting solution applied matured design approaches to minimize the program risk with innovative methods to address the impacts of scale.

impulse thruster valve↗

NASA NTRS2008

James Webb Space Telescope - L2 Communications for Science Data Processing

JWST is the first NASA mission at the second Lagrange point (L2) to identify the need for data rates higher than 10 megabits per second (Mbps). JWST will produce approximately 235 Gigabits of science data every day that will be downlinked to the Deep Space Network (DSN). To get the data rates desired required moving away from X-band frequencies to Ka-band frequencies. To accomplish this transition, the DSN is upgrading its infrastructure. This new range of frequencies are becoming the new standard for high data rate science missions at L2. With the new frequency range, the issues of alternatives antenna deployment, off nominal scenarios, NASA implementation of the Ka-band 26 GHz, and navigation requirements will be discussed in this paper. JWST is also using Consultative Committee for Space Data Systems (CCSDS) standard process for reliable file transfer using CCSDS File Delivery Protocol (CFDP). For JWST the use of the CFDP protocol provides level zero processing at the DSN site. This paper will address NASA implementations of Ground Stations in support of Ka-band 26 GHz and lesson learned from implementing a file base (CFDP) protocol operational system.

Johns, Alan↗

NASA NTRS2018

Synoptic Ozone, Cloud Reflectivity, and Erythemal Irradiance from Sunrise to Sunset for the Whole Earth as Viewed by the DSCOVR Spacecraft from the Earth-Sun Lagrange 1 Orbit

EPIC (Earth Polychromatic Imaging Camera) on board the DSCOVR (Deep Space Climate Observatory) spacecraft is the first earth science instrument located near the earth-sun gravitational plus centrifugal force balance point, Lagrange 1. EPIC measures earth-reflected radiances in 10 wavelength channels ranging from 317.5 to 779.5 nm. Of these channels, four are in the UV range 317.5, 325, 340, and 388 nm, which are used to retrieve O3, 388 nm scene reflectivity (LER: Lambert equivalent reflectivity), SO2, and aerosol properties. These new synoptic quantities are retrieved for the entire sunlit globe from sunrise to sunset multiple times per day as the earth rotates in EPIC's field of view. Retrieved ozone amounts agree with ground-based measurements and satellite data to within 3 %. The ozone amounts and LER are combined to derive the erythemal irradiance for the earth's entire sunlit surface at a nadir resolution of 1818 km2 using a computationally efficient approximation to a radiative transfer calculation of irradiance. The results show very high summertime values of the UV index (UVI) in the Andes and Himalayas (greater than 18), and high values of UVI near the Equator at equinox.

Cloud reflectivity↗

NASA NTRS2015

NASA's Space Launch System: An Evolving Capability for Exploration

Designed to enable human space exploration missions, including eventually landings on Mars, NASA's Space Launch System (SLS) represents a unique launch capability with a wide range of utilization opportunities, from delivering habitation systems into the "proving ground" of lunar-vicinity space to enabling high-energy transits through the outer solar system. Substantial progress has been made toward the first launch of the initial configuration of SLS, which will be able to deliver more than 70 metric tons of payload into low Earth orbit (LEO). Preparations are also underway to evolve the vehicle into more powerful configurations, culminating with the capability to deliver more than 130 metric tons to LEO. Even the initial configuration of SLS will be able to deliver greater mass to orbit than any contemporary launch vehicle, and the evolved configuration will have greater performance than the Saturn V rocket that enabled human landings on the moon. SLS will also be able to carry larger payload fairings than any contemporary launch vehicle, and will offer opportunities for co-manifested and secondary payloads. Because of its substantial mass-lift capability, SLS will also offer unrivaled departure energy, enabling mission profiles currently not possible. The basic capabilities of SLS have been driven by studies on the requirements of human deep-space exploration missions, and continue to be validated by maturing analysis of Mars mission options, including the Global Exploration Roadmap. Early collaboration with science teams planning future decadal-class missions have contributed to a greater understanding of the vehicle's potential range of utilization. As SLS draws closer to its first launch, the Program is maturing concepts for future capability upgrades, which could begin being available within a decade. These upgrades, from multiple unique payload accommodations to an upper stage providing more power for inspace propulsion, have ramifications for a variety of missions, from human exploration to robotic science.

Robinson, Kimberly F.↗