dimanche 24 septembre 2017

ULA Successfully Launches NROL-42 Mission for the National Reconnaissance Office












ULA - NROL-42 Mission patch.

Sept. 24, 2017


Image above: A United Launch Alliance (ULA) Atlas V rocket carrying a payload for the National Reconnaissance Office lifted off from Space Launch Complex-3. Designated NROL-42, the mission is in support of national security. Image Credits: United Launch Alliance/Jeff Spotts.

A United Launch Alliance (ULA) Atlas V rocket carrying a payload for the National Reconnaissance Office lifted off  from Space Launch Complex-3 on Sept. 23, at 10:49:47 p.m. PDT. Designated NROL-42, the mission is in support of national security.

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Atlas V NROL-42 Launch Highlights

“Congratulations to the entire team for overcoming multiple challenges throughout this launch campaign. From Hurricane Irma schedule impacts to replacing to a first stage battery this week – the team maintained a clear focus on mission success,” said Laura Maginnis, ULA vice president of Government Satellite Launch. “NROL-42 marks the 25th ULA-launched NRO mission, building upon our legacy of partnership with the NRO in providing reliable access to space for our nation’s most critical missions.”

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Atlas V NROL-42 Mission Profile

This mission was launched aboard an Atlas V Evolved Expendable Launch Vehicle (EELV) 541 configuration vehicle, which includes a 5-meter payload fairing (PLF) and four solid rocket boosters. The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine, and the Centaur upper stage was powered by the Aerojet Rocketdyne RL10C engine.

This is ULA’s sixth launch in 2017 and the 121st successful launch since the company was formed in December 2006.

ULA's next launch is the NROL-52 for the National Reconnaissance Office. The launch is scheduled for Oct. 5 from Space Launch Complex-41 at Cape Canaveral Air Force Station, Florida.

An artist's concept of SBIRS GEO in space. Image Credit: Lockheed Martin

The EELV program was established by the U.S. Air Force to provide assured access to space for Department of Defense and other government payloads. The commercially developed EELV program supports the full range of government mission requirements, while delivering on schedule and providing significant cost savings over the legacy launch systems.

With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 120 satellites to orbit that aid meteorologists in tracking severe weather, unlock the mysteries of our solar system, provide critical capabilities for troops in the field and enable personal device-based GPS navigation.

For more information on ULA, visit the ULA website at http://www.ulalaunch.com/

Images (mentioned), Videos, Text, Credit: United Launch Alliance (ULA).

Greetings, Orbiter.ch

samedi 23 septembre 2017

Weekly Recap From the Expedition Lead Scientist, week of September 18, 2017












ISS - Expedition 53 Mission patch.

Sept. 23, 2017

(Highlights: Week of September 18, 2017) - Crew members on the International Space Station wrapped up a low-temperature combustion investigation that was sparked by a discovery made during a previous run of experiments aboard the orbiting laboratory, and could help scientists develop new engines and fuels that are more efficient and less harmful to the environment.


Image above: The Zero Boil-OFF Tank (ZBOT) on the International Space Station has a large "ullage" bubble and several smaller bubbles around it. The experimental hardware uses an experimental fluid to test active heat removal and forced jet mixing as alternative means for controlling tank pressure for volatile fluids. Image Credit: NASA.

“Cool flames” were first discovered during the Flammability and Extinction (FLEX) study on the space station in 2013. The Cool Flames investigation followed in an effort to better understand this unique burning behavior. The final run of Cool Flames Investigation led to the dismantling and stowing of the hardware, bringing the operations for the study on the space station to a close. Data from the investigation will now be analyzed by Earth scientists. Some types of fuels initially burn very hot, then appear to go out — but they continue burning at a much lower temperature with no visible flames. These phenomena are called cool flames. The Cool Flames Investigation provides new insight into this phenomenon, as well as new data on fire safety in space.

The Advanced Research Thermal Passive Exchange (ARTE) investigation was also completed. This new heat pipe design reduces the weight of thermal systems while also increasing their efficiency. Scientists want to evaluate the performance of the ARTE heat pipes to keep the overall mass low and save on energy. We won’t have to actively cool some areas with a fan, or actively heat other areas. If successful, this highly conductive pipe could be integrated into future spacecraft, aircraft of supercomputer systems on Earth.


Image above: NASA astronaut Randy Bresnik conducts a study into muscle atrophy on the International Space Station. He conducted an ultrasound on his calf muscle while exercising using a mechanism created by ESA. Image Credit: NASA.

As ARTE completed a heating investigation, the Zero Boil-Off Tank (ZBOT) study was working on better ways to regulate cryogenic fluid or gas. Rocket fuel, spacecraft heating and cooling systems and sensitive scientific instruments rely on very cold cryogenic fluids. Heat from the environment around the cryogenic tanks can cause their pressures to rise, which requires releasing or "boiling off" fluid to release the excess pressure, or actively cooling the tanks in some way. ZBOT uses an experimental fluid to test active heat removal to control tank pressure for volatile fluids.

Cryogenic tanks require complicated storage and flow solutions for fluids that act as both liquid and gas, depending on their temperatures. Results from this investigation into phase change and heat transport will provide data that could improve models used to design lightweight, efficient, and long-duration cryogenic storage in space for fuel tanks and engines, but can also help in the development of storage facilities in laboratories and other industries on Earth.


Image above: ESA astronaut Paolo Nespoli works on packing the SpaceX-Dragon cargo craft, which returned to Earth this week, returning a variety of technological and biological research. Image Credit: NASA.

NASA astronaut Randy Bresnik , ESA (European Space Agency) astronaut Paolo Nespoli and Russian cosmonaut Sergey Ryazanskiy participated in research into muscle atrophy in space with the Myotendinous and Neuromuscular Adaptation to Long-term Spaceflight (Sarcolab-3) study involving the Muscle Atrophy Research & Exercise System (MARES). This investigation studies the adaptation and deterioration of the soleus, or calf muscle, where it joins the Achilles tendon, which links it to the heel and carries loads from the entire body. Muscle fiber samples are taken from crew members before and after flight and analyzed for changes in structural or chemical properties. MRI and ultrasound tests and electrode stimulation are conducted to help assess muscle and tendon changes caused by microgravity exposure.

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Space to Ground: Busy Crew: 09/22/2017

Video above: NASA's Space to Ground is a weekly update on what is happening on the International Space Station. Social media users can post with #spacetoground to ask questions or make a comment. Video Credit: NASA.

By understanding the mechanisms behind loss of muscle mass in space, scientists can develop countermeasures that are more effective for the crews -- pharmacological, dietary or exercise-based – and maintain or improve the health and performance of astronauts in orbit. Scientists also can gain insight into certain muscular conditions on Earth. Solutions developed for astronauts could be used for rehabilitation of patients with a variety of muscular conditions.

International Space Station (ISS). Image Credit: NASA

Progress was made on other investigations this week, including: Tropical Cyclone, Combustion Integration Rack (CIR), Long Duration Sorbent Testbed (LDST), Marrow, Actiwatch, Dosetracker, ACME, Fine Motor Skills, FIR LMM, Rodent Research-9, and Lighting Effects.

Related links:

Cool Flames investigation: https://www.nasa.gov/mission_pages/station/research/experiments/1947.html

Advanced Research Thermal Passive Exchange (ARTE): http://www.nasa.gov/mission_pages/station/research/experiments/1911.html

Zero Boil-Off Tank (ZBOT): https://www.nasa.gov/mission_pages/station/research/experiments/1270.html

Sarcolab-3: https://www.nasa.gov/mission_pages/station/research/experiments/738.html

Muscle Atrophy Research & Exercise System (MARES): http://blogs.esa.int/iriss/2015/09/07/the-mares-machine/

Tropical Cyclone: http://www.nasa.gov/mission_pages/station/research/experiments/1973.html

Combustion Integration Rack (CIR): https://www.nasa.gov/mission_pages/station/research/experiments/326.html

Long Duration Sorbent Testbed (LDST): http://www.nasa.gov/mission_pages/station/research/long_duration_sorbent_testbed

Marrow: https://www.nasa.gov/mission_pages/station/research/experiments/1931.html

Dosetracker: https://www.nasa.gov/mission_pages/station/research/experiments/1933.html

ACME: https://www.nasa.gov/mission_pages/station/research/experiments/1908.html

Fine Motor Skills: http://www.nasa.gov/mission_pages/station/research/experiments/1767.html

FIR: https://www.nasa.gov/mission_pages/station/research/experiments/360.html

LMM: https://www.nasa.gov/mission_pages/station/research/experiments/541.html

Rodent Research-9: https://www.nasa.gov/mission_pages/station/research/experiments/2440.html

Lighting Effects: https://www.nasa.gov/mission_pages/station/research/experiments/2279.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA/Kristine Rainey/John Love, Lead Increment Scientist Expeditions 53 & 54.

Best regards, Orbiter.ch

vendredi 22 septembre 2017

Hubble's Cool Galaxy with a Hot Corona











NASA - Hubble Space Telescope patch.

Sept. 22, 2017


Galaxy NGC 6753, imaged here by the NASA/ESA Hubble Space Telescope, is a whirl of color — the bursts of blue throughout the spiral arms are regions filled with young stars glowing brightly in ultraviolet light, while redder areas are filled with older stars emitting in the cooler near-infrared.

But there is more in this galaxy than meets the Hubble eye.  At 150 million light-years from Earth, astronomers highlighted NGC 6753 as one of only two known spiral galaxies that were both massive enough and close enough to permit detailed observations of their coronas. Galactic coronas are huge, invisible regions of hot gas that surround a galaxy’s visible bulk, forming a spheroidal shape. Coronas are so hot that they can be detected by their X-ray emission, far beyond the optical radius of the galaxy. Because they are so wispy, these coronas are extremely difficult to detect.

Galactic coronas are an example of telltale signs astronomers seek to help them determine how galaxies form. Despite the advances made in past decades, the process of galaxy formation remains an open question in astronomy. Various theories have been suggested, but since galaxies come in all shapes and sizes — including elliptical, spiral, and irregular — no single theory has so far been able to satisfactorily explain the origins of all the galaxies we see throughout the Universe.

Hubble Space Telescope

For images and more information about Hubble, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
http://www.spacetelescope.org/

Image, Animation, Credits: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt/Text Credits: European Space Agency/NASA/Karl Hille.

Best regards, Orbiter.ch

Soaring Over Jupiter












NASA - JUNO Mission logo.

Sept. 22, 2017


This striking image of Jupiter was captured by NASA’s Juno spacecraft as it performed its eighth flyby of the gas giant planet.

The image was taken on Sept. 1, 2017 at 2:58 p.m. PDT (5:58 p.m. EDT). At the time the image was taken, the spacecraft was 4,707 miles (7,576 kilometers) from the tops of the clouds of the planet at a latitude of about -17.4 degrees.

Citizen scientist Gerald Eichstädt processed this image using data from the JunoCam imager. Points of interest are “Whale's Tail” and "Dan's Spot.”

JunoCam's raw images are available for the public to peruse and process into image products at:

http://www.missionjuno.swri.edu/junocam    

More information about Juno is at:

https://www.nasa.gov/juno and http://missionjuno.swri.edu

Image, Text,  Credits: NASA/Tony Greicius/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt.

Greetings, Orbiter.ch

Positive, Negative or Neutral, It All Matters: NASA Explains Space Radiation











NASA logo.

Sept. 22, 2017

Charged particles may be small, but they matter to astronauts. NASA’s Human Research Program (HRP) is investigating these particles to solve one of its biggest challenges for a human journey to Mars: space radiation and its effects on the human body.

“One of our biggest challenges on a mission to Mars is protecting astronauts from radiation,” said NASA Space Radiation Element Scientist Lisa Simonsen, Ph.D.. “You can’t see it; you can’t feel it.  You don’t know you’re getting bombarded by radiation.”

A common misconception of space radiation is that it’s similar to radiation on Earth. It’s actually quite different. On Earth, radiation coming from the sun and space is mainly absorbed and deflected by our atmosphere and magnetic field.

The main type of radiation people think of on Earth is found in the dentist's office – X-rays. Shielding against X-rays and other types of electromagnetic radiation usually consists of wearing a heavy, lead blanket.


Image above: Galactic cosmic rays (GCRs) are of most concern to NASA. It is challenging to shield against GCRs. They come from exploding stars called supernovae. Image Credit: NASA.

Space radiation, however, is different because it has sufficient energy to collide violently with the nuclei that make up shielding and human tissue. These so-called nuclear collisions cause both the incoming space radiation and shielding nuclei to break-up into many different types of new particles, referred to as secondary radiation.

“In space, there is particle radiation, which is basically everything on the periodic table, hydrogen all the way up through nickel and uranium, moving near the speed of light,” said NASA Research Physicist Tony Slaba, Ph.D. “NASA doesn’t want to use heavy materials like lead for shielding spacecraft because the incoming space radiation will suffer many nuclear collisions with the shielding, leading to the production of additional secondary radiation. The combination of the incoming space radiation and secondary radiation can make the exposure worse for astronauts.”

The HRP is focused on investigating these effects of space radiation on the human body especially those associated with galactic cosmic rays (GCRs).

“There are three main sources of space radiation, but GCRs are of most concern to researchers for a mission to Mars,” said NASA Research Physicist John Norbury, Ph.D. “GCRs that come from exploding stars known as supernovae outside the solar system are the most harmful to the human body.”

Other space radiation sources include the Van Allen Belts where radiation particles are trapped around the Earth and solar particle events (SPEs) which are associated with solar flares and coronal mass ejections and are more likely to occur during times of intense solar activity.

But GCRs are first in mind for the HRP researchers who create countermeasures to protect astronauts from space radiation. The challenge is obtaining adequate data on the GCR exposure and biological consequences. Researchers use NASA’s Space Radiation Laboratory (NSRL) to investigate the effects of ionizing radiation but space radiation is difficult to simulate on Earth. A radiation dose in a lab setting could be more concentrated and given over a shorter timeframe than what an astronaut actually experiences during a year in space.

As NASA prepares for a journey to Mars, it will continue to use, enhance and develop a variety of technologies to protect astronauts. International Space Station dosimeters, Orion’s Hybrid Electronic Radiation Assessor, and the Radiation Assessment Detector can measure and identify high-energy radiation. Protons, neutrons and electrons may be small but they will always matter to NASA.

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Positive, Negative or Neutral, It All Matters: NASA Explains Space Radiation

Video above: Charged particles may be small, but they matter to astronauts. NASA’s Human Research Program (HRP) is investigating these particles to solve one of its biggest challenges for a human journey to Mars: space radiation and its effects on the human body. Video Credit: NASA.

NASA's Human Research Program (HRP) is dedicated to discovering the best methods and technologies to support safe, productive human space travel. HRP enables space exploration by reducing the risks to astronaut health and performance using ground research facilities, the International Space Station, and analog environments. This leads to the development and delivery of a program focused on: human health, performance, and habitability standards; countermeasures and risk mitigation solutions; and advanced habitability and medical support technologies. HRP supports innovative, scientific human research by funding more than 300 research grants to respected universities, hospitals and NASA centers to over 200 researchers in more than 30 states.

Related links:

NASA’s Space Radiation Laboratory (NSRL): http://www.nasa.gov/analogs/nsrl

NASA's Human Research Program (HRP): http://www.nasa.gov/hrp

Orion’s Hybrid Electronic Radiation Assessor: https://www.nasa.gov/feature/scientists-and-engineers-evaluate-orion-radiation-protection-plan

Radiation Assessment Detector: https://mars.nasa.gov/msl/mission/instruments/radiationdetectors/rad/

Journey to Mars: https://www.nasa.gov/topics/journeytomars/index.html

Image (mentioned), Video (mentioned), Text, Credits: NASA/Timothy Gushanas/Human Research Strategic Communications/Amy Blanchett/Laurie Abadie.

Greetings, Orbiter.ch

Soyuz rocket carrying Glonass-M Successfully Increased on the Target Orbit












ROSCOSMOS - Glonass Program patch.

09/22/2017

Soyuz 2.1b carrying Glonass-M launch

On September 22, 2017 at 03:03 Moscow time from the State Test Cosmodrome Plesetsk in the Arkhangelsk Region, with the military calculation of the Space Forces of the Military Space Forces, a successful launch of the Soyuz-2.1b medium-range rocket with the Russian navigation satellite Glonass-M was carried out.

The launch was conducted under the general supervision of the commander of the Space Forces, the deputy commander-in-chief of the Air and Space Forces, Colonel General Alexander GOLOVKO.

video
Glonass-M launched by Soyuz-2.1b

Three minutes after the launch, the Soyuz-2.1b launch vehicle was taken for escorted by the ground-based automated control complex of the Main Test Space Center named after German Titov.

At the estimated time, the GLONASS-M spacecraft was launched into the target orbit by the Fregat upper stage and accepted for control of the ground forces of the Space Forces of the VKS.

A stable telemetry connection is established and maintained with the spacecraft. The on-board systems of the GLONASS-M spacecraft function normally.

Glonass-M navigation satellite

This is the third launch of the Soyuz-2 launch vehicle from the Plesetsk space center in 2017. Flight tests of the Soyuz-2 space rocket complex began at the Plesetsk space center on November 8, Over the past thirteen years, 31 launch of Soyuz-2 carrier rockets from modernization stages 1a, 1b and 1c have been carried out from the northern launch site. In addition, 20 launches of the Soyuz-2 rocket were carried out from the Baikonur cosmodrome.

The spacecraft put into orbit will join the orbital grouping of the Russian Global Navigation Satellite System GLONASS. At present, 25 spacecrafts are part of the GLONASS orbital group, of which the new-generation GLONASS-K spacecraft is being tested, and one GLONASS-M spacecraft is being investigated by the chief designer of the system.

The developers and manufacturers of the Soyuz-2.1b booster rocket, Fregat upper stage, Glonass-M spacecraft are the companies of the ROSKOSMOSA RKC Progress, NGOs Lavochkin and Information Satellite Systems named after Academician MF Reshetnev.

ROSCOSMOS Press Release: https://www.roscosmos.ru/24115/

Images, Video, Text, Credits: ROSCOSMOS/SciNews/Orbiter.ch Aerospace/Roland Berga.

Greetings, Orbiter.ch

jeudi 21 septembre 2017

NASA Measures Hurricane Maria's Torrential Rainfall, Sees Eye Re-open

















NASA - EOS Terra Mission patch / NASA - EOS Aqua Mission logo / NASA - Suomi NPP Mission logo.

Sept. 21, 2017

Maria (Atlantic Ocean)

Hurricane Maria has caused catastrophic flooding in Puerto Rico and left a wake of heavy rainfall that NASA measured using a fleet of satellites in space. NASA satellite imagery also saw Maria's eye close up as it tracked across Puerto Rico and re-open after its exit.

Calculating Maria's Rainfall 


Image above: From Sept. 17 to early Sept. 21, 2017 NASA's IMERG estimated that rainfall totals greater than 10 inches (254 mm) were common along Maria's track. IMERG rainfall estimates indicated that more than 20 inches (512 mm) of rain fell over a large part of Puerto Rico. During that period Maria dropped heavy rain in the Leeward Islands, Virgin Islands and Puerto Rico. Image Credit: NASA.

The Global Precipitation Measurement mission or GPM core satellite, a joint mission between NASA and the Japan Aerospace Exploration Agency can measure rainfall from space. That rainfall data, combined with data from other satellites provided a tally of Hurricane Maria's rainfall over the course of several days.

At NASA's Goddard Space Flight Center in Greenbelt, Maryland, NASA's Integrated Multi-satellitE Retrievals for GPM (IMERG) data were used to estimate the total amount of rain that Hurricane Maria dropped from Sept. 17 to early Sept. 21, 2017. During that period Maria dropped heavy rain in the Leeward Islands, Virgin Islands and Puerto Rico. IMERG estimated that rainfall totals greater than 10 inches (254 mm) were common along Maria's track. IMERG rainfall estimates indicated that more than 20 inches (512 mm) of rain fell over a large part of Puerto Rico.

Extreme flooding was reported in the streets of San Juan, the capital of Puerto Rico. The National Weather Service issued flash flood warnings for the entire island. Hurricane Maria has now moved to the northwest of Puerto Rico but is still expected to contribute to rainfall over the island on Friday. Feeder bands of thunderstorms are transporting rain over Puerto Rico and the Dominican Republic even as the hurricane moves toward the Turks and Caicos Islands.

Hurricane Maria's Eye Winks

Hurricane Maria made landfall near Yabucoa, Puerto Rico, around 6:15 a.m. EDT/AST on Sept. 20. Maximum sustained winds in the hurricane were reported to be 149.5 mph (130 knots) as Maria moved toward San Juan, Puerto Rico.


Image above: On Sept. 20 at 10:50 a.m. EDT (14:50 UTC) NASA's Terra satellite provided this visible image as Hurricane Maria was moving over Puerto Rico. The eye had become obscured by clouds. Image Credits: NASA Goddard MODIS Rapid Response Team.

On Sept. 20 at 10:50 a.m. EDT (14:50 UTC) NASA's Terra satellite provided a visible image as Hurricane Maria was moving over Puerto Rico. Maria's eye had become obscured by clouds.

On Sept. 21 at 1:54 a.m. EDT (0554 UTC) the VIIRS instrument aboard NASA-NOAA's Suomi NPP satellite provided a thermal image of Hurricane Maria after it re-emerged eye moved off the coast of Puerto Rico and as just northeast of Hispaniola. The image showed that the eye had become visible again and powerful thunderstorms with very cold cloud tops surrounded it's eye.


Image above: This infrared image of Hurricane Maria was taken from the AIRS instrument aboard NASA's Aqua satellite on Sept. 21 at 2:05 a.m. EDT (0605 UTC). Maria’s eye opened up, and the orange spots indicate that there are clear areas where the sea surface shows through. Powerful thunderstorms (purple) circle the large eye. Image Credits: NASA JPL, Ed Olsen.

Another infrared image of Hurricane Maria was taken from the Atmospheric Infrared Sounder or AIRS instrument aboard NASA's Aqua satellite on Sept. 21 at 2:05 a.m. EDT (0605 UTC). Maria’s eye opened up, and there were clear areas where the sea surface shows through. Powerful thunderstorms circle the large eye where cloud top temperatures of strong thunderstorms in Maria's eyewall as cold as or colder than minus 63 degrees Fahrenheit (minus 53 Celsius).

Warnings and Watches in Effect on Sept. 21

The National Hurricane Center (NHC) said a Hurricane Warning is in effect for the Dominican Republic from Cabo Engano to Puerto Plata, Turks and Caicos Islands and the Southeastern Bahamas. A Tropical Storm Warning is in effect for the Dominican Republic west of Puerto Plata to the northern border of the Dominican Republic and Haiti, Dominican Republic west of Cabo Engano to Andres/Boca Chica. A Tropical Storm Watch is in effect for the Central Bahamas.


Image above: On Sept. 21 at 1:54 a.m. EDT (0554 UTC) the VIIRS instrument aboard NASA-NOAA's Suomi NPP satellite provided this thermal image of Hurricane Maria after it re-emerged eye moved off the coast of Puerto Rico and as just northeast of Hispaniola. Image Credits: NOAA/NASA Goddard Rapid Response Team.

Location and Status of Maria on Sept. 21

At 11 a.m. EDT/AST (1500 UTC), the large eye of Hurricane Maria was located near 20.2 north latitude and 69.1 degrees west longitude. That's about 105 miles (175 km) east-northeast of Puerto Plata, Dominican Republic and about 155 miles (255 km) southeast of Grand Turk Island. Maria is moving toward the northwest near 9 mph (15 kph), and this general motion is expected to continue through tonight. The minimum central pressure based on aircraft data is 960 millibars.

Data from an Air Force Reserve reconnaissance aircraft indicate that maximum sustained winds remain near 115 mph (185 kph) with higher gusts. Maria is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Some strengthening is possible during the next day or so. Hurricane-force winds extend outward up to 60 miles (95 km) from the center and tropical-storm-force winds extend outward up to 150 miles (240 km).


video
NASA Measures Hurricane Maria's Track of Torrential Rainfall


Video above: From Sept. 17 to early Sept. 21, 2017 NASA's IMERG estimated that rainfall totals greater than 10 inches (254 mm) were common along Maria's track. IMERG rainfall estimates indicated that more than 20 inches (512 mm) of rain fell over a large part of Puerto Rico. During that period Maria dropped heavy rain in the Leeward Islands, Virgin Islands and Puerto Rico. Video Credits: NASA/JAXA, Hal Pierce.

The NHC said "A turn toward the north-northwest is forecast early Friday, with that motion continuing through early Saturday. On the forecast track, Maria's eye will continue to pass offshore of the northern coast of the Dominican Republic today, and then move near or just east of the Turks and Caicos Islands and southeastern Bahamas tonight and on Friday, Sept. 22.

For forecast updates on Maria, visit: http://www.nhc.noaa.gov/

Suomi NPP (National Polar-orbiting Partnership): http://www.nasa.gov/mission_pages/NPP/main/index.html

Aqua Satellite: https://www.nasa.gov/mission_pages/aqua/index.html

NASA's Integrated Multi-satellitE Retrievals for GPM (IMERG): https://pmm.nasa.gov/category/keywords/imerg

Terra Satellite: http://www.nasa.gov/mission_pages/terra/index.html

Images (mentioned), Video (mentioned), Text, Credits: NASA’s Goddard Space Flight Center, by Rob Gutro.

Greetings, Orbiter.ch