Category: Satellites

A Delta 2 rocket blasted off early this morning at 3:46 a.m. EDT bringing the Ocean Surface Topography Mission-Jason 2 into Earth orbit. The satellite will use a radar altimeter to precisely measure the height of ocean surfaces, which have been rising in recent years because of increasing temperatures. The data will be used to monitor effects of climate change on sea level and to improve global weather, climate and ocean forecasts. NASA said the new satellite, which is a cooperative effort between the US and France, will also improve hurricane forecasting.

“Global warming is causing the oceans to rise at a rate of about 3 millimeters per year, and this is a direct result of increasing the temperature of the atmosphere,” said Josh Willis an oceanographer from JPL. “That causes glaciers and ice sheets to melt, raising the levels of the ocean. But also, the ocean itself absorbs heat. And when that happens, again the water expands, stands a little taller, and this causes sea level rise as well, so the altimeter on OSTM, or Jason 2, will see both of these effects at it circles the Earth.”

Similar observations began in 1992 with a spacecraft dubbed TOPEX/Poseidon and have continued with the current Jason 1 satellite. The two Jasons will fly in tandem.

Together with Jason 1, the two spacecraft will double global data coverage. This tandem mission will improve our knowledge of tides in coastal and shallow seas and internal tides in the open ocean, while improving our understanding of ocean currents and eddies.

Jason 2 will map the sea surface highs and lows every 10 days, tracking changes and helping scientists keep tabs on climate, and even weather.

Measurements of sea-surface height, or ocean surface topography, reveal the speed and direction of ocean currents and tell scientists how much of the sun’s energy is stored by the ocean. Combining ocean current and heat storage data is key to understanding global climate variations.

OSTM/Jason 2’s five primary instruments are improved versions of those flying on Jason 1. These technological advances will allow scientists to monitor conditions in ocean coastal regions — home to about half of Earth’s population. Compared with Jason 1 measurements, OSTM/Jason 2 will have substantially increased accuracy and provide data to within 25 kilometers (15 miles) of coastlines, nearly 50 percent closer to shore than in the past. Such improvements will be welcome news for all those making their living on the sea, from sailors and fishermen to workers in offshore industries. NOAA will use the improved data to better predict hurricane intensity, which is directly affected by the amount of heat stored in the upper ocean.

Sources: NASA, JPL

When a solar flare blasts energetic particles and magnetic flux at Earth, our satellites are on the front line. As coronal mass ejections (CMEs) interact with the Earth’s magnetosphere, there is a huge injection of energetic electrons into the Earth’s radiation belts. This can have dire consequences for the satellites that we depend on for communications around the globe. All is not lost however. An international team of scientists have stumbled upon a possible, innovative solution to discharge these troublesome electrons into the atmosphere: bathe the skies in radio waves.

The magnetosphere (protective layers of geomagnetic field lines) traps energetic particles in a volume of space known as the Van Allen belt. Our satellites are constantly travelling through this high radiation environment. Most satellites are shielded from all but the worst the Van Allen belt can throw at them, but should the Sun send a high concentration of energetic particles at the Earth after a solar flare, the environment in the magnetosphere becomes a very dangerous place. Should the delicate circuitry on board the spacecraft be hit by energetic particles (a situation that possibly caused Mars Odyssey to be switched to “safe-mode”), the satellite could be irreversibly damaged.

Now, a chance discovery by French and New Zealand scientists indicate that magnetospheric electrons can be discharged into the atmosphere by using ground-based radio transmitters. This finding comes from a new paper to be published in the journal Geophysical Research Letters. Rory Gamble, a PhD student of the University of Otago in Dunedin, New Zealand, and his colleagues were analysing the data from DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), a satellite sensitive to radiation changes in the magnetosphere. As the satellite passed over a military transmitter in Western Australia, they noticed that magnetospheric electrons were discharged into the atmosphere, thereby removing them from the magnetosphere.

“We were able to determine that this transmitter has a direct effect on the electrons in the radiation belts [in the magnetosphere], it caused those electrons to crash into the top of the atmosphere and be removed from the radiation belts.” – Rory Gamble

This finding is a very exciting development for the human-influenced manipulation of the levels of radiation in the magnetosphere. During periods of high solar activity, when energetic electrons are expected to populate the radiation belts in higher densities, there could be a system in place to bathe the sky in radio waves, allowing safer passage for satellites. This phenomenon has been known to exist when transmitting radio waves in space, but this is the first example of electron discharge from a ground-based transmitter.

Source: ABC

Where you want to go depends on where you are. And if you’ve got a GPS system in your hands, and the most accurate clock ever sent into space overhead, you’ll always know exactly where you are. ESA’s GIOVE-B satellite blasted into space on Sunday, taking the next step for the deployment of a European satellite navigation system.

The GIOVE-B satellite lifted off from the Baikonur Cosmodrome on April 27th at 4:16 am local time (22:13 UTC Saturday), and placed the Galileo In-Orbit Validation Element B (GIOVE-B) satellite into a 23,200 km orbit.

Ground controllers confirmed that the satellite deployed its twin solar panels, and it was generating electricity within about 5 hours of launch.

On board GIOVE-B are two redundant rubidium atomic clocks, but these are just backups. The really accurate timepiece is the Passive Hydrogen Maser, which has a stability of better than 1 nanosecond a day. There’s no risk of losing track of time with this – it’s the most stable clock operating in Earth orbit.

GIOVE-B is still just a technology demonstration. It will be followed in 2010 by the launch of the first 4 operational satellites that make up the Galileo navigation system. The European plan to eventually have a constellation of 30 identical satellites operating in a constellation.

Original Source: ESA News Release

Space junk, space debris, space waste — call it what you want, but just as junk and waste cause problems here on Earth, in space spent booster stages, nuts and bolts from ISS construction, various accidental discards such as spacesuit gloves and cameras, and fragments from exploded spacecraft could turn into a serious problem for the future of spaceflight if actions to mitigate the threat are not taken now. The European Space Operations Centre has put together some startling images highlighting this issue. Above is a depiction of the trackable objects in orbit around Earth in low Earth orbit (LEO–the fuzzy cloud around Earth), geostationary Earth orbit (GEO — farther out, approximately 35,786 km (22,240 miles) above Earth) and all points in between.


Between the launch of Sputnik on 4 October 1957 and 1 January 2008, approximately 4600 launches have placed some 6000 satellites into orbit; about 400 are now travelling beyond Earth on interplanetary trajectories, but of the remaining 5600 only about 800 satellites are operational – roughly 45 percent of these are both in LEO and GEO. Space debris comprise the ever-increasing amount of inactive space hardware in orbit around the Earth as well as fragments of spacecraft that have broken up, exploded or otherwise become abandoned. About 50 percent of all trackable objects are due to in-orbit explosion events (about 200) or collision events (less than 10).

Officials from the space shuttle program have said the shuttle regularly takes hits from space debris, and over 80 windows had to be replaced over the years. The ISS occasionally has to take evasive maneuvers to avoid collisions with space junk. And of course, this debris is not just sitting stationary: in orbit, relative velocities can be quite large, ranging in the tens of thousands of kilometers per hour.

For the Envisat satellite, for example, the ESA says the most probable relative velocity between the satellite and a debris object is 52,000 kilometers per hour. If a debris objects hits a satellite, the ISS or the Shuttle, at those speeds it could cause severe damage or catastrophe.

Above is a depiction of debris in polar orbit around Earth. From the image below, it’s evident how explosions of spacecraft causes even more scattered debris. Even after the end of the mission, batteries and pressurised systems as well as fuel tanks explode. This generates debris objects, which contribute to the growing population of materials in orbit, ranging from less than a micrometer to 10 centimeters or more in size.

About 40% of ground-trackable space debris come from explosions, now running at four to five per year. In 1961, the first explosion tripled the amount of trackable space debris. In the past decade, most operators have started employing on-board passive measures to eliminate latent sources of energy related to batteries, fuel tanks, propulsion systems and pyrotechnics. But this alone is insufficient. At present rates, in 20 or 30 years, collisions would exceed explosions as a source of new debris.

The ESA says it is crucial to start immediately to implement mitigation measures. This image shows a simulation of the the 2112 GEO environment in the case when no measures are taken. In the top panel, with mitigation measures, a much cleaner space environment can be observed if the number of explosions is reduced drastically and if no mission-related objects are ejected. The bottom panel shows the “business-as-usual” scenario, without any mitigation measures taken. However, to stop the ever-increasing amount of debris, more ambitious mitigation measures must be taken. Most importantly, spacecraft and rocket stages have to de-orbited and returned to Earth after the completion of their mission.

They’ll burn up in the atmosphere, or splash down in uninhabited ocean areas. In the case of telecommunication and other satellites operating in the commercially valuable geostationary zone, they should boost their satellites to a safe disposal orbit, as shown below.

There are other measures, like reducing the number of mission-related objects and controlling the risk for reentry, but these are the basics. The issue is that such mitigation measures cost fuel and operational time, and therefore they increase cost. In the commercial world, this may competitiveness, unless there is an international consensus to accept such costs.

Original News Source: ESA

On the March 24th, a story hit the web from Brazil asking for help identifying a mysterious-looking sphere found in farmland. The black, shiny object appeared to be wrapped in fibrous material and it was hot to the touch. Immediately thoughts of extra-terrestrial origin came to mind…

Today, several news sources covered the discovery of a mysterious spherical object found in the Australian outback last year. The farmer who made the discovery has only just started to make enquiries into what the object actually is.

So are the two objects connected in some way? Are they indeed from outer space?

The answer is “yes”, and “yes”. But don’t go getting too excited, they’re not bits from a broken alien spacecraft.

Before their origins are explained, a bit of background: The first story to be released was from Brazil on Monday. Just a small story on Daniel Drehmer’s blog, asking “a space geek from Digg” (Digg.com being the social bookmarking site) for help to identify this strange object found by Sebastião Marques da Costa who described the orb as being hot to the touch. Either it has been heated by the Sun, or it had just crashed to Earth. On seeing the object, it does make for good science fiction material. It’s a very strange looking thing, one meter in diameter, contrasting with the green countryside.

I was so intrigued by the story, I kept an eye on the blog. The following day, the Second Wave reported that an answer had been found. Obviously the geeks on Digg had been paying attention and identified the object as a Composite Overwrapped Pressure Vessel (or COPV). Put very basically, it’s a high pressure container for inert gases. The space shuttle carries COPVs and it seems likely that these containers will be used for a variety of space missions. They are built with a carbon fibre or Kevlar overcoat to provide reinforcement against the vast pressure gradient between the inside and outside of the container.

If the COPVs are so reinforced, it seems reasonable that they may survive re-entry through the Earth’s atmosphere.

So what about our Australian farmer? Looking at the picture, the strange object in the Australian outback has some striking similarities to the Brazilian orb (only a lot more damaged).

Today many news sites picked up on the Australian find (well, last year’s find), and call me suspicious, but the timing couldn’t be better. The Australian farmer, James Stirton, who found the object made the surprising statement to the Reuters news agency:

“I know a lot of about sheep and cattle but I don’t know much about satellites. But I would say it is a fuel cell off some stage of a rocket.”

That’s one very well informed guess. Perhaps he’s a Digg reader…?

Either way, it would be interesting to find out to what space mission these COPVs belonged to, as it appears they are highly efficient at not only storing fuels being flown into space, they also crash to Earth pretty much intact.

Sources: Reuters, The Second Wave