Posted on by VirtualAstro

June 21 ATV Re-Entry: A Man-Made Fireball In The Sky

ATV re-entry. Credit: ESA

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The Johannes Kepler ATV (Automated Transfer Vehicle) has undocked from the International Space station and will re- enter Earth’s atmosphere on June 21st ending its mission in fiery destruction.

The ATV has been docked with the ISS since February, where it delivered supplies, acted as a giant waste disposal and boosted the orbit of the International Space Station with its engines.

The X-wing ATV delivered approximately 7 tonnes of supplies to the station and will be leaving with 1,200kg of waste bags, including unwanted hardware.

The Johannes Kepler ATV-2 approaches the International Space Station. Docking of the two spacecraft occurred on Feb. 24, 2011. Credit: NASA

On June 21st at 17:07 GMT the craft will fire its engines and begin its suicide mission, tumbling and burning up as a bright manmade fireball over the Pacific Ocean. Any leftover debris will strike the surface of the Pacific ocean at 20:50 GMT.

During the ATV’s re-entry and destruction there will be a prototype onboard flight recorder (Black Box) transmitting data to Iridium satellites, as some aspects of a controlled destructive entry are still not well known.

ESA says that this area is used for controlled reentries of spacecraft because it is uninhabited and outside shipping lanes and airplane routes. Extensive analysis by ESA specialists will ensure that the trajectory stays within safe limits.

There still are some chances to see the ISS and Johannes Kepler ATV passing over tonight, but if you in a location where you can see the south Pacific skies starting at about 20:00 GMT, keep an eye out for a glorious manmade fireball.

A shower of debris results as the ATV continues its plunge through the atmosphere. Credit: ESA

Read more about the re-entry at ESA.

Posted on by Nancy Atkinson

ATV In-Flight Refueling for ISS Set for Mid-May

The ATV Johannes Kepler docked at the International Space Station. Credit: NASA

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ESA’s Automated Transfer Vehicle Johannes Kepler is more than just a cargo carrier for the International Space Station, it is also an on-orbit refueling station and orbit booster. On May 17-19, 2011 the Kepler ATV is scheduled to conduct its first refueling of the ISS, as it will transfer about 850.6 liters (225 gallons) of propellant for the station’s own thrusters for future boosts in orbit.

Preparations for the ISS refueling began on March 22 with a leak test of the propellant transfer lines, to ensure the connections between the ISS and ATV-2 were completely sealed; the test was a success, meaning that as of now, everything is go for the station’s refueling.

The Johannes Kepler ATV-2 approaches the International Space Station. Docking of the two spacecraft occurred on Feb. 24, 2011. Credit: NASA

In mid-March, the ATV increased the ISS’s orbit with a 882-second (14 and a half minutes) burn, giving the ISS an extra push of about 2.1 m/s. In all, Kepler brought nearly 10,000 pounds (4,500 kilograms) of propellant that has been used by its thrusters to boost the space station to a new altitude of 400 kilometers (248 miles) above the Earth. This will be the new “normal” for the station’s orbit. Previously, the ISS orbited about 350 km (220 miles) up.

The main benefit of raising the station’s altitude is to cut the amount of fuel needed to keep it there by more than half. This also means that visiting vehicles will not be able to carry as much cargo as they could if they were launching to the station at a lower altitude since they will need more fuel to reach the station, but it also means that not as much of that cargo needs to be propellant.

The orbit of the ISS degrades because Earth’s atmosphere — though tenuous at those altitudes – expands and contracts through the Sun’s influence, and there are enough molecules that contact the surfaces of its large solar array panels, the large truss structure, and pressurized modules to change its speed, or velocity, which is about 28,000 kilometers an hour (17,500 mph).

At the ISS’s old altitude, the space station uses about 19,000 pounds of propellant a year to maintain a consistent orbit. At the new, slightly higher altitude, the station is expected to expend about 8,000 pounds of propellant a year. And that will translate to a significant amount of food, water, clothing, research instruments and samples, and spare parts that can be flown on the cargo vehicles that will keep the station operational until 2020 and beyond.

Kepler also sent a breath of fresh air to the station by transferring about 8kg of oxygen to the ISS in March, which was the first re-pressurization of the ISS’s internal atmosphere conducted by Kepler.

A view the space station as Discovery approaches for docking. Credit: NASA

Sources: ATV Blog, NASA