7 results on '"Spacecraft"'
Search Results
2. The 90-Year-Old Would-Be Astronaut Who Finally Gets His Chance at Space.
- Author
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De Avila, Joseph
- Subjects
- *
ASTRONAUTS , *INDUSTRIAL goods , *AEROSPACE industries - Abstract
Ed Dwight, the first Black man to train as an astronaut in the 1960s, will finally get his chance to go to space at the age of 90. Although he never made it to space during his initial training, Dwight became a celebrity in the Black community and later became a renowned sculptor focusing on Black history. He will be the oldest person to fly to space, joining five others on a Blue Origin flight that will last approximately 11 minutes. Dwight's flight is seen as a vindication and a correction of past injustices. [Extracted from the article]
- Published
- 2024
3. U.S. Moon Lander Is Safe—but Resting on Its Side.
- Author
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Maidenberg, Micah
- Subjects
- *
MOON , *LUNAR surface - Abstract
Intuitive Machines, the company behind the Odysseus moon lander, announced that the spacecraft tipped over after landing on the moon. The vehicle is currently resting on its side, supported by a rock. While some antennas are facing the lunar surface and cannot be used, the scientific devices on board are still functional. The company is investigating the cause of the tipping and plans to continue with operations on the moon's surface. [Extracted from the article]
- Published
- 2024
4. Detecting early warning signals of tree mortality in boreal North America using multiscale satellite data.
- Author
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Rogers BM, Solvik K, Hogg EH, Ju J, Masek JG, Michaelian M, Berner LT, and Goetz SJ
- Subjects
- Arctic Regions, North America, Time Factors, Trees growth & development, Climate Change, Environmental Monitoring methods, Forests, Spacecraft, Trees physiology
- Abstract
Increasing tree mortality from global change drivers such as drought and biotic infestations is a widespread phenomenon, including in the boreal zone where climate changes and feedbacks to the Earth system are relatively large. Despite the importance for science and management communities, our ability to forecast tree mortality at landscape to continental scales is limited. However, two independent information streams have the potential to inform and improve mortality forecasts: repeat forest inventories and satellite remote sensing. Time series of tree-level growth patterns indicate that productivity declines and related temporal dynamics often precede mortality years to decades before death. Plot-level productivity, in turn, has been related to satellite-based indices such as the Normalized difference vegetation index (NDVI). Here we link these two data sources to show that early warning signals of mortality are evident in several NDVI-based metrics up to 24 years before death. We focus on two repeat forest inventories and three NDVI products across western boreal North America where productivity and mortality dynamics are influenced by periodic drought. These data sources capture a range of forest conditions and spatial resolution to highlight the sensitivity and limitations of our approach. Overall, results indicate potential to use satellite NDVI for early warning signals of mortality. Relationships are broadly consistent across inventories, species, and spatial resolutions, although the utility of coarse-scale imagery in the heterogeneous aspen parkland was limited. Longer-term NDVI data and annually remeasured sites with high mortality levels generate the strongest signals, although we still found robust relationships at sites remeasured at a typical 5 year frequency. The approach and relationships developed here can be used as a basis for improving forest mortality models and monitoring systems., (© 2018 John Wiley & Sons Ltd.)
- Published
- 2018
- Full Text
- View/download PDF
5. Terrestrial gross primary production inferred from satellite fluorescence and vegetation models.
- Author
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Parazoo NC, Bowman K, Fisher JB, Frankenberg C, Jones DB, Cescatti A, Pérez-Priego O, Wohlfahrt G, and Montagnani L
- Subjects
- Carbon Cycle, Europe, Fluorescence, Models, Theoretical, North America, Photosynthesis, Seasons, South America, Spacecraft, Sunlight, Chlorophyll analysis, Chlorophyll metabolism, Climate, Environmental Monitoring methods, Plants metabolism
- Abstract
Determining the spatial and temporal distribution of terrestrial gross primary production (GPP) is a critical step in closing the Earth's carbon budget. Dynamical global vegetation models (DGVMs) provide mechanistic insight into GPP variability but diverge in predicting the response to climate in poorly investigated regions. Recent advances in the remote sensing of solar-induced chlorophyll fluorescence (SIF) opens up a new possibility to provide direct global observational constraints for GPP. Here, we apply an optimal estimation approach to infer the global distribution of GPP from an ensemble of eight DGVMs constrained by global measurements of SIF from the Greenhouse Gases Observing SATellite (GOSAT). These estimates are compared to flux tower data in N. America, Europe, and tropical S. America, with careful consideration of scale differences between models, GOSAT, and flux towers. Assimilation of GOSAT SIF with DGVMs causes a redistribution of global productivity from northern latitudes to the tropics of 7-8 Pg C yr(-1) from 2010 to 2012, with reduced GPP in northern forests (~3.6 Pg C yr(-1) ) and enhanced GPP in tropical forests (~3.7 Pg C yr(-1) ). This leads to improvements in the structure of the seasonal cycle, including earlier dry season GPP loss and enhanced peak-to-trough GPP in tropical forests within the Amazon Basin and reduced growing season length in northern croplands and deciduous forests. Uncertainty in predicted GPP (estimated from the spread of DGVMs) is reduced by 40-70% during peak productivity suggesting the assimilation of GOSAT SIF with models is well-suited for benchmarking. We conclude that satellite fluorescence augurs a new opportunity to quantify the GPP response to climate drivers and the potential to constrain predictions of carbon cycle evolution., (© 2014 John Wiley & Sons Ltd.)
- Published
- 2014
- Full Text
- View/download PDF
6. Satellite-observed photosynthetic trends across boreal North America associated with climate and fire disturbance.
- Author
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Goetz SJ, Bunn AG, Fiske GJ, and Houghton RA
- Subjects
- Arctic Regions, Environmental Monitoring, Fires, North America, Seasons, Time, Climate, Photosynthesis physiology, Spacecraft, Trees physiology
- Abstract
We analyzed trends in a time series of photosynthetic activity across boreal North America over 22 years (1981 through 2003). Nearly 15% of the region displayed significant trends, of which just over half involved temperature-related increases in growing season length and photosynthetic intensity, mostly in tundra. In contrast, forest areas unaffected by fire during the study period declined in photosynthetic activity and showed no systematic change in growing season length. Stochastic changes across the time series were predominantly associated with a frequent and increasing fire disturbance regime. These trends have implications for the direction of feedbacks to the climate system and emphasize the importance of longer term synoptic observations of arctic and boreal biomes.
- Published
- 2005
- Full Text
- View/download PDF
7. Continuous time transfer using GPS carrier phase.
- Author
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Dach R, Schildknecht T, Springer T, Dudle G, and Prost L
- Subjects
- Calibration, Environmental Monitoring instrumentation, Environmental Monitoring methods, Europe, Geography, North America, Radio Waves, Sensitivity and Specificity, Spacecraft, Stochastic Processes, Time Factors, Computer Simulation, International Cooperation, Models, Theoretical, Satellite Communications instrumentation, Satellite Communications standards
- Abstract
The Astronomical Institute of the University of Berne is hosting one of the Analysis Centers (AC) of the International GPS Service (IGS). A network of a few GPS stations in Europe and North America is routinely analyzed for time transfer purposes, using the carrier phase observations. This work is done in the framework of a joint project with the Swiss Federal Office of Metrology and Accreditation (METAS). The daily solutions are computed independently. The resulting time transfer series show jumps of up to 1 ns at the day boundaries. A method to concatenate the daily time transfer solutions to a continuous series was developed. A continuous time series is available for a time span of more than 4 mo. The results were compared with the time transfer results from other techniques such as two-way satellite time and frequency transfer. This concatenation improves the results obtained in a daily computing scheme because a continuous time series better reflects the characteristics of continuously working clocks.
- Published
- 2002
- Full Text
- View/download PDF
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