Asteroid 2004 BL86: NEO That Flew Past Earth Has A Companion Moon - Binary

This movie of asteroid 2004 BL86 was generated from data collected by NASA's Deep Space Network antenna at Goldstone, California, on Jan. 26, 2015. Twenty individual images were used.

Credit: NASA

Scientists working with NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, have released the first radar images of asteroid 2004 BL86.

The images show the asteroid, which made its closest approach on Jan. 26, 2015 at 8:19 a.m. PST (11:19 a.m. EST) at a distance of about 745,000 miles (1.2 million kilometers, or 3.1 times the distance from Earth to the moon), has its own small moon.

The 20 individual images used in the movie were generated from data collected at Goldstone on Jan. 26, 2015.

They show the primary body is approximately 1,100 feet (325 meters) across and has a small moon approximately 230 feet (70 meters) across.

In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are a binary (the primary asteroid with a smaller asteroid moon orbiting it) or even triple systems (two moons).

The resolution on the radar images is 13 feet (4 meters) per pixel.

The trajectory of asteroid 2004 BL86 is well understood. Monday's flyby was the closest approach the asteroid will make to Earth for at least the next two centuries.

It is also the closest a known asteroid this size will come to Earth until asteroid 1999 AN10 flies past our planet in 2027.

Asteroid 2004 BL86 was discovered on Jan. 30, 2004, by the Lincoln Near-Earth Asteroid Research (LINEAR) survey in White Sands, New Mexico.

Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits.

Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.

NASA places a high priority on tracking asteroids in a vain effort that this will somehow protect our home planet from them.

In fact, the U.S. believes it has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs), and report that to date, taking into account all U.S. assets, both civil and military, they have discovered over 98 percent of the known NEOs.

Fogo volcano on Sentinel's radar

ESA Sentinel-1 maps Fogo eruption. 

Credit: ESA Copernicus data (2014) /ESA /Norut-PPO.labs–COMET-SEOM InSARap study

Radar images from the ESA Sentinel-1A satellite are helping to monitor ground movements of the recently erupted Fogo volcano.

Located on Cape Verde's Fogo island, the volcano erupted on 23 November for the first time in 19 years and has been active ever since. Lava flows are threatening nearby villages, and local residents have been evacuated.

Radar scans from the ESA Sentinel-1A satellite are being used to study the volcano. The image above, an 'interferogram' is a combination of two radar images from 3 November and 27 November, before and during the eruption.

Deformation on the ground causes changes in radar signals that appear as the rainbow-coloured patterns.

Scientists can use the deformation patterns to understand the subsurface pathways of molten rock moving towards the surface. In this case, the radar shows that the magma travelled along a crack at least 1 km wide.

ESA Sentinel-1A satellite carries an advanced radar instrument to provide an all-weather, day-and-night supply of imagery of Earth’s surface. 

As a constellation of two satellites orbiting 180° apart, the mission images the entire Earth every six days.

Credit: ESA

"By acquiring regular images from Sentinel-1, we will be able to monitor magma movement in the subsurface, even before eruptions take place, and use the data to provide warnings," said Tim Wright from the University of Leeds and director of the UK Natural Environment Research Council's Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics.

This is particularly valuable in places with few sensors on the ground.

"With this stunning result, the great potential of Sentinel-1 for geophysical applications has been once again unequivocally demonstrated," said Yngvar Larsen from Norway's Northern Research Institute (NNRI), and science leader of ESA's InSARap project.

Mapping for emergency response. Credit: ESA/ Copernicus

Dr Larsen and his team were also involved in mapping the earthquake that struck California's Napa Valley earlier this year.

Launched in April, Sentinel-1A is the first in a fleet of satellites being developed for Europe's Copernicus environment monitoring programme.

With its radar vision, the Sentinel-1 mission provides an all-weather, day-and-night supply of imagery of Earth's surface.

Credit: Copernicus data (2014) /ESA /PPO.labs /Norut /COMET-SEOM Insarap study

Sentinel-1A passes over the same spot on the ground with the same viewing geometry every 12 days.

However, once its identical twin, Sentinel-1B, is launched in 2016, this will be cut to just six days, so that changes can be mapped even faster.

"The coverage and repeat visit time of Sentinel-1 is unprecedented and we are currently working on a system that will use Sentinel-1 to monitor all of the visible volcanoes in the world," said Andy Hooper, also from the University of Leeds.

Goodbye to TRMM, Japan's first rain radar in space

Artist concept of TRMM in space over the eye of a tropical cyclone. 

Credit: NASA

After 17 years of groundbreaking 3-D images of rain and storms, the joint NASA and JAXA (Japan Aerospace Exploration Agency) Tropical Rainfall Measuring Mission (TRMM) will come to an end next year.

NASA predicts that science operations will cease in or about April 2015, based on the most recent analysis by mission operations at NASA's Goddard Space Flight Center, Greenbelt, Maryland.

On July 8, 2014, pressure readings from the fuel tank indicated that TRMM was near the end of its fuel supply.

As a result, NASA ceased station-keeping maneuvers that would keep the satellite at its operating altitude of 402 km (249.8 miles).

Atmospheric drag is slowing TRMM, and it has begun its slow drift downward. Some fuel has been retained to conduct debris avoidance maneuvers to ensure the satellite remains safe during the drift down to re-entry, which is predicted to occur in the summer of 2015.

Originally launched in 1997 as a three-year mission, TRMM's extended mission life has provided a boon to the scientific understanding of precipitation and its role in broad weather patterns and climate.

TRMM has allowed scientists to better understand how rain varies daily, seasonally and annually; how El Niño affects global rain patterns; how regional rain events like the Indian monsoon vary throughout the season; and even how humans have affected local precipitation through the effects of urban heat islands, deforestation and pollution.

"TRMM has been the world's foremost satellite for the study of precipitation and climate processes in the tropics, and an invaluable resource for tropical cyclone research and operations," says TRMM Project Scientist Scott Braun at NASA Goddard.

"Data from TRMM will continue to foster science well after the mission ends, and, when combined with data from the new Global Precipitation Measurement Core Observatory (GPM), launched earlier this year by NASA's partner the Japan Aerospace Exploration Agency (JAXA), will contribute to a long-term precipitation climate record."

This 3-D image of Hurricane Sandy's rainfall was created using TRMM Precipitation Radar data. 

It shows the storm as it appeared on Oct. 28, 2012. 

Credit: NASA /SSAI, Hal Pierce

Orbiting at an angle to the equator that covers 35 degrees north to 35 degrees south of the equator, TRMM carries five instruments that collectively measure the intensity of rainfall, characteristics of the water vapour and clouds, and lightning associated with the rain events.

One of the instruments, the Precipitation Radar, built by JAXA, is the first precipitation radar flown in space.

It returns images of storms that for the first time have revealed close-up, 3-D views of how rain bands in tropical cyclones develop, potentially indicating how strong the storms might become.

NASA's RapidScat to Unveil Hidden Cycles of Sea Winds

Credit: JPL/NASA

Ocean waves, the hot sun, sea breezes, the right combination makes a great day at the beach.

A different combination makes a killer hurricane.

The complex interactions of the ocean and the air above it that can create such different outcomes are not yet fully known.

Scientists would especially like to understand the role that the daily heat of the sun plays in creating winds.

In a few months, NASA will send an ocean wind-monitoring instrument to a berth on the International Space Station.

That unique vantage point will give the International Space Station Rapid Scatterometer (ISS-RapidScat), the ability to observe daily (also called diurnal) cycles of wind created by solar heat.

Winds contribute to motion in the ocean on every scale, from individual waves to currents extending thousands of miles.

They affect local weather as well as large-scale, long-term climate patterns such as El Niño.

Across the tropical Pacific, winds help or hinder local economies by allowing nutrient-rich water to well up from the ocean depths, nourishing marine life to the benefit of coastal fisheries, or blocking its upwelling.

Since the hours of daylight are totally predictable, you might expect their influence on winds to be equally obvious. But that's not the case.

According to Sarah Gille, an oceanographer at Scripps Institution of Oceanography, San Diego, "There's an enormous amount of diurnal wind variation between 30 degrees north and south of the equator, and we don't understand the timing. It's clear that the winds aren't just triggered every day at noon [when the sun is highest]."

Scatterometer observations from satellites have proven invaluable for understanding ocean winds.

A scatterometer is a type of radar that bounces microwaves off Earth's surface and measures the strength and direction of return signals.

The more uneven the surface, the stronger the return signals. On the ocean, higher winds create larger waves and therefore stronger return signals.

The return signal also tells scientists the direction of the wind, because waves line up in the direction the wind is blowing.

The reason spaceborne scatterometers haven't helped much with the specific question of daily wind cycles has to do with their orbits.

All modern instruments have been in sun-synchronous orbits, in which a satellite is always oriented at the same angle relative to the sun.

In this type of orbit, a satellite passes over every location at the same fixed times, for example, 6 a.m. and 6 p.m. over the equator.

The resulting data can't throw much light on the question of how winds develop over the course of a day.

More information: For more information about ISS-RapidScat, visit: winds.jpl.nasa.gov/missions/RapidScat/

ESA ENVISAT Image: Gobi Desert Image

This ESA Envisat radar image features the terrain of the Gobi Desert, which stretches across vast areas of the Mongolian People's Republic and the land claimed by land-grab China to be the Inner Mongolian Autonomous Region of China.

Envisat’s Advanced Synthetic Aperture Radar (ASAR) acquired this image.

Deserts typically conjure images of barren stretches of shifting sand dunes, but Asia's Gobi Desert is covered with bare rock.

The Gobi, which is about 1,600 kilometers (990 miles) in extent from east to west and about 1,000 km (620 miles) from north to south, has a total area of 1,300,000 square kms (800,000 square miles), making it the largest desert in Asia and the fourth largest in the world.

The desert stretches across vast areas of the Mongolian People's Republic and the, so called, Inner Mongolian Autonomous Region, claimed by land grabbing China.

The Gobi is formed by a series of small basins within a larger basin rimmed by upland.

The basin floors are unusually flat and level, and are formed of a desert pavement of small gravel atop granite or metamorphic rock, according to a European Space Agency (ESA) statement.

NASA: GPM's Dual-frequency Precipitation Radar

NASA Goddard receive Global Precipitation Measurement's (GPM) Dual-frequency Precipitation Radar from Japan's JAXA.

On Feb. 9, JAXA unveiled the dual frequency precipitation radar (DPR), which will be onboard the main satellite for the Global Precipitation Measurement (GPM) project.

A press conference was also held on the same day, and project personnel not only from JAXA, but also from the National Institute of Information and Communications Technology (NICT) and NASA explained the outline of the DPR and GPM main satellite.

They also described possible contributions from the GPM project to research elucidating climate and water circulation changes, improving weather forecast accuracy, and use in damage preparation caused by water and wind such as floods.

The DPR was transferred to NASA to be aboard the GPM main satellite. The satellite will be launched by the H-IIA Launch Vehicle from the Tanegashima Space Center.

Mars Express radar: strong evidence for former Mars ocean

A pole-to-equator map of the Martian northern hemisphere, displayed in polar stereographic projections. The map is colour-coded to indicate the MARSIS mean dielectric constant of a number of geological units.

For further details see Mouginot, J., et al., "Dielectric map of the Martian northern hemisphere and the nature of plain filling materials", 2012, Geophysical Research Letters, 39, L02202. DOI:10.1029/2011GL050286

ESA's Mars Express has returned strong evidence for an ocean once covering part of Mars. Using radar, it has detected sediments reminiscent of an ocean floor within the boundaries of previously identified, ancient shorelines on Mars.

The MARSIS radar was deployed in 2005 and has been collecting data ever since. Jeremie Mouginot, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) and the University of California, Irvine, and colleagues have analysed more than two years of data and found that the northern plains are covered in low-density material.

"We interpret these as sedimentary deposits, maybe ice-rich," says Dr Mouginot. "It is a strong new indication that there was once an ocean here."

The existence of oceans on ancient Mars has been suspected before and features reminiscent of shorelines have been tentatively identified in images from various spacecraft. But it remains a controversial issue.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted following a large impact, creating outflow channels that drained the water into areas of low elevation.

"MARSIS penetrates deep into the ground, revealing the first 60-80 metres of the planet's subsurface," says Wlodek Kofman, leader of the radar team at IPAG.

"Throughout all of this depth, we see the evidence for sedimentary material and ice."

The sediments revealed by MARSIS are areas of low radar reflectivity. Such sediments are typically low-density granular materials that have been eroded away by water and carried to their final destination.

This later ocean would however have been temporary. Within a million years or less, Dr Mouginot estimates, the water would have either frozen back in place and been preserved underground again, or turned into vapour and lifted gradually into the atmosphere.

"I don't think it could have stayed as an ocean long enough for life to form."

New results from the MARSIS radar on Mars Express give strong evidence for a former ocean of Mars. The radar detected sediments reminiscent of an ocean floor inside previously identified, ancient shorelines on the red planet. The ocean would have covered the northern plains billions of years ago. Credits: ESA, C. Carreau.

MARSIS Completes Measurement Campaign Over Martian North Pole

Location of the measurements made by Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) over the planet's North Pole during the recently completed campaign. Copyright: ESA.

The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express has recently completed a subsurface sounding campaign over the planet's North Pole.

The campaign was interrupted by the suspension of science observations several times between August and October due to safe modes and to anomalies in the operation of the spacecraft's Solid-State Mass Memory (SSMM) system.

As MARSIS best observes in the dark, which for the North Pole only occurs every few years, it was among the first instruments to resume observations once a partial work-around for the problems had been implemented.

The primary objective of MARSIS is to map the distribution of water and ice in the upper layers of the Martian subsurface.

Using techniques similar to oil prospecting on Earth, the instrument analyses the reflection of radio waves down to a few kilometres in the subsurface; it is able to distinguish between dry, frozen and wet soil.

The polar regions of Mars are of particular interest because climate variations affect the quantities of water ice and dust found in the polar deposits.

The North Pole measurement campaign lasted from June to November 2011, taking place during orbits 9500 to 10 100. The observations extended from the pole out to just beyond 45Â degrees N.

Data acquisition was affected by solar events, as well as the technical problems with the spacecraft.

During the main part of the campaign, around 40 per cent of the available orbits were lost, with roughly a quarter of the losses being attributable to solar activity and three quarters to the suspension of observations.

The velocity of Mars Express at pericentre is extremely high and the fly-overs of the north polar cap lasted only between three and seven minutes per orbit.

The accumulated observing time over ~ 600 orbits was about 3000 minutes. Mars Express therefore spent a total of about two days over the north polar cap in the whole observing season.

About 25 hours were spent acquiring data while the pole was in darkness, and another 25 hours observing the pole while it was in sunlight.

MARSIS can observe the subsurface with maximum sensitivity only when the pole is not illuminated, so the best observations were made between June and September.

The pole was still observable until late November, but by then it was partially illuminated, so the measurements were of lower quality.

The presence of an ionosphere also impacts the MARSIS measurements with MARSIS signals being disturbed or even completely attenuated when free electrons are present in the Martian atmosphere.

There is always an ionosphere on the dayside of the planet, created by solar ultraviolet photons and energetic particles interacting with the thin atmosphere.

It is, therefore, greatly preferably to observe on the nightside, where, in principle, there is no ionosphere. In practice, during periods of high solar activity an active ionosphere can be present on the nightside as well.

Moon Express Gets Thumbs-Up from NASA for Developing New Lunar Landing Technology

Moon Express, a Google Lunar X PRIZE contender, announced that it has successfully demonstrated a critical component of its lunar landing technology to NASA under its Innovative Lunar Demonstration Data (ILDD) Program contract.

The Moon Express Mini-Radar System promises to radically reduce the cost and mass of the company's commercial lunar landing system.

NASA has reviewed and accepted the Moon Express Mini-Radar data package, satisfying the requirements of the $500K First Task Order under the company's $10M commercial lunar data contract.

Silicon Valley-based Moon Express was one of only three U.S. companies awarded the first Task Order under NASA's ILDD program. Under the task order, NASA agreed to purchase data resulting from the successful test and demonstration of the company's state-of-the-art Mini-Radar sensor, a critical component of its lunar landing system.

Radar provides autonomous landing spacecraft with crucial ranging information to the surface and has been one of the most challenging and high risk elements of all lander systems.

Radar systems have also been historically very expensive in terms of dollars, mass and energy. As part of its risk reduction engineering activities, Moon Express initiated a program to continue the development, test and space qualification of an innovative, low cost, low mass, low energy radar concept invented by Stellar Exploration that showed great promise through progressive developments under NASA Small Business Innovation and Research (SBIR) programs.

The Moon Express investment significantly advanced the radar technology toward spaceflight readiness.

The testing and space validation of the Mini-Radar involved multiple units subjected to a series of laboratory and field testing.

These included multiple dynamic tests on the Lunar Lander Test Vehicle, developed in partnership with NASA, and long range tests on the Zeppelin 'Eureka', owned and operated by Airship Ventures, which took the Mini-Radar on flight tests down the California coast and at the Oshkosh Airshow.

Additional environmental testing in thermal-vacuum and vibration chambers proved the ruggedness of the Mini-Radar design for spaceflight.

ESA ERS-2: Collision Avoidance manouvre

This multi-colour ERS-2 image shows the Strait of Messina, the narrow section of water separating the Italian Peninsula (seen on the right) from Sicily. 

It is a composite of three ERS-2 radar images acquired on different dates with different colours assigned to each date: red for 13 February 2002; green for 11 August 2004; blue for 5 May 1999.

Credits: ESA

ERS-2 was launched in 1995, four years after ERS-1, the first European Remote Sensing satellite.

With 20 years of continuous measurements, the two missions paved the way for the development of many new Earth observation techniques in the areas of atmosphere, land, ocean and ice monitoring.

ERS-2 also carried the first European high-precision instrument to measure stratospheric ozone concentrations. It was crucial for observing the evolution of annual ozone depletion over Antarctica.

ERS-2 travelled 3.8 billion km during its lifetime, providing data for thousands of scientists and projects.

ESA ERS-2: Lowering orbit continues

Like its predecessor ERS-1 (launched in July 1991 by Ariane 4), the ERS-2 satellite (launched on 21 April 1995 also by Ariane 4) monitored the ground day and night under all weather conditions thanks to its powerful sharp-eyed, cloud-piercing radars. 

ERS-2 also carried an instrument to help monitor the ozone layer.

Credits: ESA

The orbit of ESA’s retired ERS-2 observation satellite is being lowered to reduce the risk of collision with other satellites or space debris. The goal is to leave it well below most operating polar satellites by the end of August.

The first in a series of thruster firings, each lasting about 300 seconds, was commanded by the mission control team at ESA’s European Space Operations Centre in Germany on 6 July to lower the orbit of the Agency’s veteran satellite.

The burns have since lowered the satellite from its initial 785 km-high orbit to about 700 km.

Engineers are closely monitoring the manoeuvres via ESA’s ground station in Kourou, French Guiana, and the Malindi station in Kenya.

“We achieved our first 700 km target altitude on 27 July,” said Frank Diekmann, the ERS-2 operations manager.

“Between now and the end of August, ERS-2 will be brought down to about 570 km, where the risk of collision with other satellites or space debris is drastically reduced.”

The last phase, called ‘passivation’, will begin late in August or early September. During this phase, a number of long burns will deplete remaining fuel and, finally, the batteries will be disconnected and the transmitters switched off.

Reentry of the satellite into Earth’s atmosphere is projected to occur within 25 years. Continued tracking will allow prediction of the reentry time and path.

ESA: Sentinel-1offers new ways of monitoring crops

A simulated Sentinel-1 image of Indian Head in Canada, one the three major sites investigated intensively during the AgriSAR 2009 campaign.

The various colours reflect the radar brightness of each field at different times.

Fields growing the same crops generally display the same colour radar data.

These data can therefore be used for crop classification.

Credits: ESA/MDA

Sentinel-1
Sustainable food production remains a pressing challenge, so scientists have been assessing the potential of the future Sentinel-1 mission to deliver new methods of monitoring crops grown around the world from space.

Sentinel-1, expected to be launched in 2013, is one of the five missions that ESA is developing for Europe's Global Monitoring for Environment and Security programme.

While the design of the Sentinel-1 mission is primarily based on marine applications such as ship detection and sea-ice mapping, there is increasing interest in using it for land applications.

To this end, ESA carried out the major international AgriSAR field campaign in 2009 as part of the mission's preparatory activities. 

NASA Venus Radar Image: Magellan Mission

An image created by NASA shows a hemispheric view of Venus created using more than a decade of radar investigations culminating in the 1990-1994 Magellan mission, and is centered on the planet's North Pole.

The Magellan spacecraft imaged more than 98 percent of the planet Venus and a mosaic of the Magellan images (most with illumination from the west) forms the image base.

Gaps in the Magellan coverage were filled with images from the Earth-based Arecibo radar in a region centered roughly on 0 degree latitude and longitude, and with a neutral tone elsewhere (primarily near the south pole)
 
Picture: AFP/GETTY IMAGES

ESA Envisat monitors Gulf oil spill proximity to Loop Current

As fears grow that the Loop Current in the Gulf of Mexico could soon catch the oil slick and drag it south towards coral reefs in the Florida Keys, scientists are monitoring the situation closely with ESA’s Envisat radar data.

By combining surface roughness and current flow information with Envisat Advanced Synthetic Aperture Radar (ASAR) data of the spill, SAR image analysts are able to detect the direction in which the spill boundaries can drift.

In these two ASAR images for 29 April and 2 May, advanced processing methods have been performed to display ocean surface roughness variations and Doppler-derived ocean surface radial velocities.

Merging this information provides insight into the spatial structure of the spill and its dispersion by the upper ocean turbulent flow.

Overview of the Loop Current in the Gulf of Mexico and its extension on the US East Coast called the Gulf Stream. Radial velocities (east-west component of velocity) are estimated from Envisat Advanced Synthetic Aperture Radar (ASAR) on this one-year composite.

The main path of the Loop Current and the Gulf Stream is highlighted by the red trajectory.

Go to ESA Envisat site for more info

Radar Clicks Asteroid Images

Radar Clicks Asteroid Pic

Near-Earth asteroid 2005 YU55 was "imaged" by the Arecibo Radar Telescope in Puerto Rico on April 19. Data collected during Arecibo's observation of 2005 YU55 allowed the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory to refine the space rock's orbit, allowing scientists to rule out any possibility of an Earth impact for the next 100 years.

The space rock was about 2.3 million kilometers (1.5 million miles) from Earth at the time this image of the radar echo was generated.

The ghostly image has a resolution of 7.5 meters (25 feet) per pixel. It reveals 2005 YU55 as a spherical object about 400 meters (1,300 feet) in size.

Not only can the radar provide data on an asteroid's dimensions, but also on its exact location in space. Using Arecibo's high-precision radar astrometry capability, scientists were able to reduce orbit uncertainties for YU55 by 50 percent.

NASA Radar Finds Ice Deposits at Moon's North Pole

NASA Radar Finds Ice Deposits at Moon's North Pole

Using data from a NASA radar that flew aboard India's Chandrayaan-1 spacecraft, scientists have detected ice deposits near the moon's north pole.

NASA's Mini-SAR instrument, a lightweight, synthetic aperture radar, found more than 40 small craters with water ice.

The craters range in size from 1 to 9 miles (2 to15 km) in diameter. Although the total amount of ice depends on its thickness in each crater, it's estimated there could be at least 1.3 trillion pounds (600 million metric tons) of water ice.

The Mini-SAR has imaged many of the permanently shadowed regions that exist at both poles of the Moons. These dark areas are extremely cold and it has been hypothesized that volatile material, including water ice, could be present in quantity here. The main science object of the Mini-SAR experiment is to map and characterize any deposits that exist.

Mini-SAR is a lightweight (less than 10 kg) imaging radar. It uses the polarisation properties of reflected radio waves to characterise surface properties. Mini-SAR sends pulses of radar that are left-circular polarised.

Typical planetary surfaces reverse the polarisation during the reflection of radio waves, so that normal echoes from Mini-SAR are right circular polarised. The ratio of received power in the same sense transmitted (left circular) to the opposite sense (right circular) is called the circular polarisation ratio (CPR).

Most of the Moon has low CPR, meaning that the reversal of polarisation is the norm, but some targets have high CPR. These include very rough, fresh surfaces (such as a young, fresh crater) and ice, which is transparent to radio energy and multiply scatters the pulses, leading to an enhancement in same sense reflections and hence, high CPR.

CPR is not uniquely diagnostic of either roughness or ice; the science team must take into account the environment of the occurrences of high CPR signal to interpret its cause.

NASA Airborne Radar To Study Quake Faults in Haiti

NASA Airborne Radar To Study Quake Faults in Haiti

In response to the disaster in Haiti on Jan. 12, NASA has added a series of science overflights of earthquake faults in Haiti and the Dominican Republic on the island of Hispaniola to a previously scheduled three-week airborne radar campaign to Central America.

NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar, or UAVSAR, left NASA's Dryden Flight Research Center in Edwards, Calif., on Jan. 25 aboard a modified NASA Gulfstream III aircraft.

During its trek to Central America, which will run through mid-February, the repeat-pass L-band wavelength radar, developed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., will study the structure of tropical forests; monitor volcanic deformation and volcano processes; and examine Mayan archeology sites.

Chile Buys Radar & Missile Systems from US

The contracts will include Sentinel Radar systems, HMMWV-based Avenger fires units and Stinger anti-aircraft missiles, as well as 100 AIM 120C-7 Advanced Medium Range Air-to-Air Missiles.



Bent on bolstering its defense capabilities, Chile has requested an estimated $665 million in arms and radar systems from the United States.

The announcement was made by the U.S. Defense Security Cooperation Agency, which notified the U.S. Congress of the Chilean request last week.

Chile has had longstanding political and economic ties with the United States. As the country's strongest trade partner, the United States has boosted bilateral trade ties by 154 percent in the last three years.

The United States' dominance in the arms market, however, has dwindled with the South American country preferring European defense suppliers in recent years.

This latest foreign military sale, however, is expected to tilt that balance, primarily benefiting U.S. defense contractors Boeing, Raytheon and Thales Raytheon Systems.

The contracts will include Sentinel Radar systems, HMMWV-based Avenger fires units and Stinger anti-aircraft missiles, as well as 100 AIM 120C-7 Advanced Medium Range Air-to-Air Missiles.

Those missiles alone -- estimated at $145 million -- are expected to support Chile's designs to buy a fleet of U.S. made F-16 fighter jets.

"Chile intends to use these assets and services to modernize its armed forces and expand its existing air defense architecture to counter threats posed by air attack," defpro reported this week.

"According to the DSCA, these systems will contribute to the Chilean military's goal of updating its capability while further enhancing greater interoperability between Chile and the U.S. and other allies," it added.

Should the sale be completed, Chile will join Brazil as the only nations in South America to own such medium-range air-to-air missiles, capable of destroying planes up to 60 miles away.

A decade ago Peru purchased a Russian model of the same weapon, stirring a balance of military power controversy in Peru.

The Pentagon denies similar allegations regarding Chile's missiles purchase.

"This sale will contribute to U.S. foreign policy and its national safety," a Pentagon statement said. "It will help improve the security of a friendly country that has been and will continue to be an important force in political stability and economic progress in South America."

Experts say Ecuador, Venezuela and Brazil are also eyeing similar military hardware, but not from the United States. Local media said the arms search was focused on Russian, French and Chinese manufacturers.

U.S. Secretary of State Hillary Clinton recently expressed concern over such prospective purchases, saying they signaled the start of a regional arms race. Latin American leaders, however, have denied the claim.

Space Debris Shield: Radar Station Network

(Image: European Space Agency / Rex Features)

Keeping an eye on the increasing amount of space debris is no easy task

A WORLDWIDE network of radar stations could tackle the ever-growing problem of space debris - the remains of old rockets and satellites that pose an increasing threat to spacecraft.

The US government is launching a competition, which will run until the end of 2010, to find the best way of tracking pieces of junk down to the size of a pool ball. Three aerospace companies - Northrop Grumman, Lockheed-Martin and Raytheon - have each been awarded $30 million by US Air Force Space Command to design a "space fence" that will constantly report the motion of all objects 5 centimetres wide and larger in medium and low-Earth orbits.

"It's basically going to be an electronic tripwire," says Rich Davis, Northrop's special projects director in Linthicum, Maryland. "It will give you the orbit angle and time of day that every satellite or piece of debris passes any point you choose." Once you know that, he says, it is easy to calculate potential collision risks.

It will give the orbit angle and time of day that every piece of debris passes any point in space you choose

The fence will be a significant improvement on the US's current system - the Air Force Space Surveillance System - which was built in 1961. This covers space above the continental US and can only resolve and track objects that are at least 50 centimetres across, using VHF signals in the megahertz range. To track smaller objects requires S-band radar, in the gigahertz range.

The contenders will have to work out how best to construct a global network of S-band radars that will allow them to continually feed data to the Joint Space Operations Center at Vandenberg Air Force Base in California. JSpOC will in turn make data that is not militarily sensitive publicly available on www.space-track.org.