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NASA NTRSDate not supplied

NASA's Biosentinel Mission: Lessons Learned and What's Next

In the last two years, two BioSentinel payloads were launched to space. The ISS mission launched in December 2021, and returned to the ground in August 2022 after successfully completing eight biological experiments while validating the different instruments. On the other hand, the deep space mission launched onboard Artemis I in November 2022, and is currently in a heliocentric orbit over 20 million kilometers away from the Earth. Even though all hardware subsystems were validated in deep space, the microfluidic subsystems experienced anomalies throughout the initial 6-month mission. The main goals of this presentation are (1) to present flight data from the deep space payload, including biology, fluidics, electronics, data processing, and mission operations, and (2) to discuss the lessons learned – what worked and what did not – from this unique complex mission, and how these lessons are aiding in the development of the Lunar Exploration Instrument for space biology Applications (LEIA) mission, launching to the lunar surface on a commercial lander in 2026. As of the writing of this abstract, the satellite continues to work nominally, communicating to Earth via the Deep Space Network (DSN) twice per week. Importantly, the mission received and extension to continue recording data on the deep space radiation environment on its way to solar maximum (i.e., higher probability of solar particle events). BioSentinel is supported by NASA Exploration Systems Development Mission Directorate (ESDMD).

BioSentinel↗

NASA NTRS1992

LDEF: Dosimetric measurement results (AO 138-7 experiment)

One of the objectives of the AO 138-7 experiment on board the LDEF was a total dose measurement with Thermo Luminescent Detectors (TLD 100). Two identical cases, both including 5 TLDs inside various aluminum shields, are exposed to the space environment in order to obtain the absorbed dose profile induced. Radiation fluence received during the total mission length was computed, taking into account the trapped particles (solar maximum and solar minimum periods) and the cosmic rays; due to the magnetospheric shielding, the solar proton fluences are negligible on the LDEF orbit. The total dose induced by these radiations inside a semi-infinite plane shield of Al are computed with radiation transport codes. TLD reading are performed after flight; due to the mission duration increase, a post-flight calibration was necessary in order to cover the range of the flight induced dose. The results obtained, similar (+ or - 30 pct.) in both cases, are compared with the dose profile computation. In practice, these LDEF results, with less than a factor 1.4 between measurements and forecasts, reinforce the validity of the computation methods and models used for the long term evaluation of space radiation intensity on low inclination Earth orbits.

Bourrieau, J.↗

NASA NTRS1973

Mission building blocks for outer solar system exploration.

Description of the technological building blocks required for exploring the outer planets with maximum scientific yields under stringent resource constraints. Two generic spacecraft types are considered: the Mariner and the Pioneer. Following a discussion of the outer planet mission constraints, the evolutionary development of spacecraft, probes, and propulsion building blocks is presented. Then, program genealogies are shown for Pioneer and Mariner missions and advanced propulsion systems to illustrate the soundness of a program based on spacecraft modification rather than on the development of new spacecraft for each mission. It is argued that, for minimum costs, technological advancement should occur in an evolutionary manner from mission to mission. While this strategy is likely to result in compromises on specific missions, the realization of the overall objectives calls for an advance commitment to the entire mission series.

Herman, D.↗

NASA NTRS1986

The HESP (High Energy Solar Physics) project

A project for space observations of solar flares for the coming solar maximum phase is briefly described. The main objective is to make a comprehensive study of high energy phenomena of flares through simultaneous imagings in both hard and soft X-rays. The project will be performed with collaboration from US scientists. The HESP (High Energy Solar Physics) WG of ISAS (Institute of Space and Astronautical Sciences) has extensively discussed future aspects of space observations of high energy phenomena of solar flares based on successful results of the Hinotori mission, and proposed a comprehensive research program for the next solar maximum, called the HESP (SOLAR-A) project. The objective of the HESP project is to make a comprehensive study of both high energy phenomena of flares and quiet structures including pre-flare states, which have been left uncovered by SMM and Hinotori. For such a study simultaneous imagings with better resolutions in space and time in a wide range of energy will be extremely important.

Kai, K.↗

NASA NTRS1998

The Solar Wind-Inner Heliosphere

The Solar wind in the inner heliosphere, inside approximately 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses.

Suess, S. T.↗

NASA NTRS2004

Model for Solar Proton Risk Assessment

A statistical model for cumulative solar proton event fluences during space missions is presented that covers both the solar minimum and solar maximum phases of the solar cycle. It is based on data from the IMP and GOES series of satellites that is integrated together to allow the best features of each data set to be taken advantage of. This allows fluence-energy spectra to be extended out to energies of 327 MeV.

Xapos, M. A.↗

NASA NTRS1972

Solar cosmic ray hazard to interplanetary and earth-orbital space travel

A statistical treatment of the radiation hazards to astronauts due to solar cosmic ray protons is reported to determine shielding requirements for solar proton events. More recent data are incorporated into the present analysis in order to improve the accuracy of the predicted mission fluence and dose. The effects of the finite data sample are discussed. Mission fluence and dose versus shield thickness data are presented for mission lengths up to 3 years during periods of maximum and minimum solar activity; these correspond to various levels of confidence that the predicted hazard will not be exceeded.

Yucker, W. R.↗

NASA NTRS1973

Radiation hazards to synchronous satellites: The IUE (SAS-D) mission

The ambient trapped particle fluxes incident on the IUE (SAS-D) satellite were studied. Several synchronous elliptical and circular flight paths were evaluated and the effect of inclination, eccentricity, and parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 MeV, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗

NASA NTRS1973

Space radiation incident on SATS missions

A special orbital radiation study was conducted in order to evaluate mission encountered energetic particle fluxes. This information is to be supplied to the project subsystem engineers for their guidance in designing flight hardware to withstand the expected radiation levels. Flux calculations were performed for a set of 20 nominal trajectories placed at several altitudes and inclinations. Temporal variations in the ambient electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model, extrapolated to the tentative SATS launch epoch with linear time terms. Orbital flux integrations ware performed with the latest proton and electron environment models, using new computational methods. The results are presented in graphical and tabular form. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗

NASA NTRS1974

Radiation environment for ATS-F

The ambient trapped particle fluxes incident on the ATS-F satellite were determined. Several synchronous circular flight paths were evaluated and the effect of parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗

NASA NTRS2006

Visual Risk Assessment of Space Radiation Exposure for Future Space Exploration Missions

Protecting astronauts from space radiation exposure during an interplanetary mission is an important challenge for mission design and operations. If sufficient protection is not provided near solar maximum, the risk can be significant due to exposure to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR). Polyethylene shielded "storm shelters" inside spacecraft have been shown to limit total exposure from a large SPE to a permissible level, preventing acute risks and providing a potential approach to fulfill the ALARA (as low as reasonably achievable) requirement. For accurate predictions of radiation dose to astronauts involved in future space exploration missions, detailed variations of radiation shielding properties are required. Radiation fluences and doses vary considerably across both the spacecraft geometry and the body-shielding distribution. A model using a modern CAD tool ProE(TradeMark), which is the leading engineering design platform at NASA, has been developed to account for these local variations in the radiation distribution. Visual assessment of radiation distribution at different points inside a spacecraft module and in the human body for a given radiation environment are described. Results will ultimately guide in developing requirements for maximal protection for astronauts from space radiation.

Hussein, Hesham F.↗

NASA NTRSDate not supplied

Passive Cooling for Mercury Surface Lander Electronics

A significant barrier to operation of a mission on the surface of Mercury is the temperature. At Mercury’s perihelion distance of 0.313 AU, the solar intensity is 10.6 times the solar flux at Earth orbit, and at the subsolar point, the maximum surface temperature reaches 427°C. For a mission landing on the surface of Mercury at latitude of 40°S, we analyzed using passive thermal control to reduce the temperature of the critical electronics to within the operation temperature limits of silicon devices. The thermal control requires reducing the thermal conductance and infrared flux from the high temperature surface and surrounding spacecraft, and moderating the solar heat input using a surface coating with high solar reflectivity, and maximizing thermal cooling with high infrared emissivity. Using this approach, we find that we can passively cool an electronics box to a temperature of 393K (120°C) using a radiator-white surface with solar absorptivity 0.11 and infrared emissivity 0.91. This temperature is well under 175C target we use for the limits of high-temperature silicon integrated circuits, including RAM and microcontrollers. We could further reduce this operating temperature to as low as 321K (48°C) with an advanced thermal coating, a temperature well within the operational limits of conventional electronics.

Mercury↗

NASA NTRSDate not supplied

Passive Cooling for Mercury Surface Lander Electronics

Mercury↗

NASA NTRS2008

Mitigating Aviation Communication and Satellite Orbit Operations Surprises from Adverse Space Weather

Adverse space weather affects operational activities in aviation and satellite systems. For example, large solar flares create highly variable enhanced neutral atmosphere and ionosphere electron density regions. These regions impact aviation communication frequencies as well as precision orbit determination. The natural space environment, with its dynamic space weather variability, is additionally changed by human activity. The increase in orbital debris in low Earth orbit (LEO), combined with lower atmosphere CO2 that rises into the lower thermosphere and causes increased cooling that results in increased debris lifetime, adds to the environmental hazards of navigating in near-Earth space. This is at a time when commercial space endeavors are posed to begin more missions to LEO during the rise of the solar activity cycle toward the next maximum (2012). For satellite and aviation operators, adverse space weather results in greater expenses for orbit management, more communication outages or aviation and ground-based high frequency radio used, and an inability to effectively plan missions or service customers with space-based communication, imagery, and data transferal during time-critical activities. Examples of some revenue-impacting conditions and solutions for mitigating adverse space weather are offered.

Tobiska, W. Kent↗

NASA NTRS1991

Flight Support System (FSS) docking and umbilical services systems

The Satellite Servicing Project at GSFC in the early 80's developed a facility for servicing observatories in orbit when docked on the shuttle. The facility includes a three point docking ring and one or two umbilicals to provide power, data and command capability to docked payloads. This facility was used in the 1984 repair of the Solar Maximum satellite. It will be used for the Hubble repair mission in 1993, and it is planned to be used on the Explorer Platform retrieval mission in 1995 and for servicing AXAF in the late 90's. The basic three point docking mechanisms and umbilical interfaces were adopted by the OMU Project for that vehicle's remote rendezvous and docking mission capability. This would have assured a common interface for a serviceable payload for either shuttle based or remote servicing, i.e., HST. For OMU remote servicing, quick reaction docking latches were under development when that Project was cancelled. Although there is no remote servicing capability being funded at present, the EOS spacecraft configuration does include three pins compatible with the FSS latches as a contingency planning measure.

Falkenhayn, Edward↗

NASA NTRS2004

Near-Term Interstellar Sailing

A number of techniques are investigated that allow the possibility of near- ecliptic exploration beyond the Sun's heliopause (200 AU) using contemporary solar-sail spacecraft (with areal mass thickness about 0.0082 kilograms per square meters). Maximum mission duration to the heliopause was defined as one human working lifetime; missions to the Sun's gravity focus at 550 AU from the sun must take less time than one human lifetime. Options include unfurling the sail at the 0.2-AU perihelion of a parabolic solar orbit, unfurling the sail at the 0.2-AU perihelion of a 2.5-AU aphelion solar orbit, and performing a grazing gravity-assist flyby of Jupiter. Although these techniques are capable of performing the defined mission, higher-technology sails are faster.

Matloff, Gregory L.↗

NASA NTRS1979

Problems of extremely long-duration missions in the inner solar system - Example Helios

The paper deals with the exploration of the region between the earth and the sun by means of the Helios I and II spacecraft, launched in December 1974 and January 1976, respectively. Initially intended for quiet-sun observations over a period of 18 months, the mission has been extended to cover the twenty first solar cycle for which an intense sun spot maximum is predicted. The spacecraft configuration, the onboard systems, the requirements of the scientific experiments, and the operational aspects of the mission are discussed.

Kehr, J.↗

NASA NTRS2006

Impact of the Ionosphere on an L-band Space Based Radar

We have quantified the impact that the ionosphere would have on a L-band interferometric Synthetic Aperture Radar (SAR) mission using a combination of simulation, modeling, Global Positioning System (GPS) data collected during the last solar maximum, and existing spaceborne SAR data. We conclude that, except for high latitude scintillation related effects, the ionosphere will not significantly impact the performance of an L-band InSAR mission in an appropriate orbit. We evaluated the strength of the ionospheric irregularities using GPS scintillation data collected at Fairbanks, Alaska and modeled the impact of these irregularities on azimuth resolution, azimuth displacement, peak sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR). Although we predict that less than 5% of auroral zone data would show scintillation related artifacts, certain sites imaged near the equinoxes could be effected up to 25% of the time because the frequency of occurrence of scintillation is a strong function of season and local time of day. Our examination of ionospheric artifacts observed in InSAR data has revealed that the artifacts occur primarily in the polar cap data, not auroral zone data as was previously thought.

Synthetic Aperture Radar (SAR) ionospheres↗