SMOS forms three-pointed star in the sky (w/ Video)

Nov 03, 2009

(PhysOrg.com) -- Following the launch of ESA's SMOS satellite on 2 November, the French space agency CNES, which is responsible for operating the satellite, has confirmed that the instrument's three antenna arms have deployed as planned, and that the instrument is in good health.

During launch and the first few orbits around Earth, the Soil Moisture and Ocean Salinity (SMOS) instrument’s antenna arms remained safely folded up. Today, these three arms folded-out and now form a large three-pointed star shape. With its unusual shape, measuring eight metres across, SMOS can be dubbed a ‘star in the sky’.

This video is not supported by your browser at this time.
Credits: ESA - AOES Medialab

The SMOS instrument is called MIRAS - short for Microwave Imaging Radiometer with Aperture Synthesis - and is actually bigger than the satellite platform. It consists of a central hub and the three arms that have just deployed. This deployment is crucial to the success of the mission as they carry the key measuring devices: most of the 69 small antenna receivers called LICEFs.

To acquire data on soil moisture and ocean salinity, each of the LICEF antenna-receivers measures radiation emitted from Earth’s surface within the ‘L-band’, around a frequency of 1.4 GHz. This frequency provides the best sensitivity to variations in moisture in the soil and changes in the salinity of the surface waters of the oceans. In addition, this frequency is not affected too much by the weather, atmosphere and vegetation cover.

To achieve the spacial resolution required by the data users, the MIRAS instrument employs a novel use of technology. Under normal circumstances, measuring these two environmental variables using L-band would only work with a huge antenna - which would be too big to be carried by a satellite. To overcome this challenge, the SMOS mission has borrowed techniques used in radio astronomy.

Radio astronomers, searching for celestial objects that are not detectable in optical astronomy, also faced the challenge of needing to detect small signals from point sources in space at a long wavelength, requiring a big antenna. Since signals are detected as waves, signals from different telescopes can be added to synthesise the pinpointing of a much larger telescope. To achieve this, radio astronomers combined 27 radio telescopes, each 25 m in diameter, and deployed them on a Y-shaped track that can be extended up to 35 km. This is known as the Very Large Array in New Mexico, US.

Like the Very Large Array, the SMOS instrument also forms a Y-shape and through a process of interferometry the 69 small antenna receivers mimic a much larger antenna.

The deployment of the arms marks another significant milestone for ESA’s water mission. The satellite will now undergo a series of health checks within its six-month commissioning phase. So far, however, all the signs are good that this second of ESA’s Earth Explorer satellites in orbit is fit and healthy following launch and will be able to deliver the data to advance our understanding of Earth’s water cycle.

Provided by European Space Agency (news : web)

Explore further: NASA Webb's heart survives deep freeze test

add to favorites email to friend print save as pdf

Related Stories

SMOS water mission on track for launch

Feb 12, 2009

Following word from Eurockot that launch of the Earth Explorer SMOS satellite can take place between July and October this year, ESA, CNES and the prime contractor Thales Alenia Space are now making detailed preparations ...

SMOS ready to ship to launch site

May 28, 2009

ESA's next Earth Explorer, SMOS, has just passed the all-important Flight Acceptance Review, signifying that all the elements that make up the mission are in place for launch later this year. The satellite ...

SMOS arrives safely at Russian launch site

Sep 18, 2009

After leaving Thales Alenia Space in the south of France on 15 September, ESA’s SMOS Earth Explorer has arrived safely at the Plesetsk Cosmodrome in northern Russia, where it will be prepared for launch ...

Final look at ESA's SMOS and Proba-2 satellites

Oct 21, 2009

As preparations for the launch of SMOS and Proba-2 continue on schedule, the engineers and technicians at the Russian launch site say goodbye as both satellites are encapsulated within the half-shells of the ...

Recommended for you

NASA Webb's heart survives deep freeze test

1 hour ago

After 116 days of being subjected to extremely frigid temperatures like that in space, the heart of the James Webb Space Telescope, the Integrated Science Instrument Module (ISIM) and its sensitive instruments, ...

MAVEN studies passing comet and its effects

8 hours ago

NASA's newest orbiter at Mars, MAVEN, took precautions to avoid harm from a dust-spewing comet that flew near Mars today and is studying the flyby's effects on the Red Planet's atmosphere.

How to safely enjoy the October 23 partial solar eclipse

8 hours ago

2014 – a year rich in eclipses. The Moon dutifully slid into Earth's shadow in April and October gifting us with two total lunars. Now it's the Sun's turn. This Thursday October 23 skywatchers across much ...

How to grip an asteroid

8 hours ago

For someone like Edward Fouad, a junior at Caltech who has always been interested in robotics and mechanical engineering, it was an ideal project: help develop robotic technology that could one day fly on ...

User comments : 0