ROBONAUT IN ISS & DISCOVERY’S LAST MISSION STS-133

The Space Shuttle Discovery, carrying Robonaut 2 as part of its payload, has now joined the International Space Station (ISS).

This is the 39th flight of Discovery, known as mission STS-133, a historical last mission before it goes into history as the first re-usable spacecraft retiring from the programme.

NASA’s Shuttle Space programme started in the late 1960s, the beginning of the Space Age. The first Shuttle was Columbia, launched on 12 April, 1981. After 133 flights, the programme is nearing its end with three of its five spacecraft still in operation.

On 24 February 2011, the day of the launch of mission STS-133, the external liquid hydrogen tank No 137 propelled Discovery into orbit. Video surveillance of the launch showed a piece of foam from the tank getting liberated during the first 4 to 6 minutes of flight. The trajectory of the released piece of foam was traced on video recordings and although it seemed to touch the Shuttle, it was thought to be of minor concern.

During the launch operation, the external liquid hydrogen tank needs to remain extremely cold, requiring foam insulation to maintain its temperature. As burning takes place, there is a rapid use of propellant with a build-up of air at the top of the tank, this air expands rapidly generating high temperatures, which sometimes results in cracks of the insulating foam, fragments of which may break off at high speed.

The integrity of the heat shield is crucial for the success of a Shuttle mission, particularly during re-entry into Earth’s atmosphere, when friction between air particles and the spacecraft travelling at 25 times the speed of sound, generates extremely high temperatures (20,000 degrees or more). Most objects arriving to Earth from space burn-up completely at this stage (e.g. meteorites seen as shooting stars). On 1st February 2003, damage to Shuttle Columbia’s heat shield tiles lead to disintegration of the spacecraft during re-entry; a disaster from which many lessons were learnt.

As a standard procedure, a camera mounted on the Shuttle’s robotic arm is used to inspect the thermo reinforced carbon-carbon panels and heat shield tiles, looking for damage that might have occurred during launch. Data obtained from the inspection of the bottom of the wings, body and tip of the shuttle is transmitted live to Mission Control in Huston, where it is compiled into approximately 20min of video, which will be carefully examined by experts.

Among other activities, the crew from Discovery will check the spacesuits that will be transferred onto the station in preparation of space-walks of astronauts Drew and Bowen on days 5 and 7 of this mission; a “centre-line camera” will be installed in the orbital docking system in preparation for docking with the ISS.

The cargo on the Discovery includes:

• The Express Logistics Carrier (ELC), a platform designed to support external payloads that will be mounted to the space station.
• Robonaut2 (R2), the first humanoid robot that will be tested in micro-gravity and ultimately used to assist spacewalk operations.
• Leonardo, the new Italian module that will be installed in the Space Station. Once its payload of supplies is emptied, it will add storage space to the station.
• The Developmental Test Objective (DTO) that will use the DragonEye 3D Flash light intensification detection and ranging (LIDAR) sensor, a 3-dimensional navigation sensor that will be tested for the Dragon Spacecraft. The latter is the first privately operated spacecraft designed to carry up to 7 passengers or cargo to and from the ISS. It will be launched by a rocket and splashdown in the Pacific Ocean on return, the project is in its final testing stages.

Previous to docking with the ISS on 26Feb at 19:16UTC (approximately 19:16 GMT), Discovery will perform a head-to-tail turn to expose its underside to the space station. From the ISS, astronauts will use cameras equipped with telephoto lenses to take photographs of the heat shield for further examination.

DISCOVERY DOCKS TO ISS – 26 FEBRUARY 2011

At 18:00UTC on 26 February 2011, Discovery was given the “go” command from Flight Control Huston to initiate the “rendezvous-pitch manoeuvre,” flipping over as it approached the ISS. Astronauts Cady Coleman and Paolo Nespoli took many pictures from the station, using cameras fitted with 400mm and 800mm lenses respectively; a planned procedure they practiced thoroughly during training at NASA.

The manoeuvre went well with spectacular views of Discovery as both spacecraft travelled over South America. Just before the flip, the shadow of ISS could be seen on the shuttle.

Shortly after recovery from the pitch, the shuttle initiated approach for docking, moving slowly towards the station controlled manually by the crew.

At 19:10 UTC they initiated their final approach as the spacecraft travelled over Australia. Shuttle Discovery docked to the Harmony Module of the ISS at 19:14 UTC.

A slight misalignment of the spacecraft delayed the opening of the hatches. They were eventually opened at 21:16 UTC. Shortly after, the crew of Discovery entered the ISS in a joyful meeting marking the completion of the first part of mission STS-133, the last mission of this spacecraft. Almost all members had cameras to record this historical moment.

Once the astronauts were on board, they continued with their scheduled activities. Before the end of their working day, the crew installed the Express Logistics Carrier (ELC - 2), which was done exclusively via the Canadarms (No1 on board the Shuttle and No2 on the Space Station). They also transferred the spacesuits that they prepared for the spacewalks scheduled for Monday 28 Feb. and Wednesday 2nd March.

References

¤ “My Exploration - About Robonaut 2” (2011). National Aeronautics and Space Administration (NASA). [Online]. Available here. (Accessed: 25 February 2011).
¤ “NASA-TV” (2011). NASA. [Online]. Available here. (Accessed: 25 February 2009).
¤ Nuscorpii223 (2008). “Answer to: Why do things burn up in the atmosphere upon re-entry?” Yahoo Answers. [Online]. Available here. (Accessed: 25 February 2009).
¤ “Space Shuttle” (2006). NASA. [Online]. Available here. (Accessed: 25 February 2011).
¤ “STS-133: Discovery” (2011). NASA. [Online]. Available here. (Accessed: 25 February 2011).

Images

¤ All images edited by ren@rt. Source: NASA.

ATV “JOHANNES KEPLER” LAUNCHED BY ESA

The European Space Agency (ESA) launched the rocket Ariane-5 from French Guiana on Wednesday 16 February 2011. The spacecraft carries the Automated Transfer Vehicle (ATV) “Johannes Kepler,” named after the famous German astronomer and mathematician author of “Astronomia Nova,” published 400 years ago (ESA, 2009).

This was the 42nd successful launch of the expendable launch system Ariane-5 and its heaviest to date with a weight of 20.1 ton (Thisdell, 2011).

Once into orbit, the ATV will approach and autonomously dock with Russia’s Zvezda module of the International Space Station and deliver its 7ton cargo including: 800 kg of fuel, 840 litres of water, 100 kg of oxygen and other gases, and vital supplies for the crew of the space station.

The ATV’s size is close to that of a double decker bus, it is 9.7m tall with a diameter of 4.4m, its solar arrays span 22m. The frontal payload zone contains racks with supplies, the middle section holds gas and water tanks and the propulsion module is located in the back. It was built in Bremen, Germany with contributions from many European countries (ESA, 2011).

The artist impression above shows the automatic docking of ATV “Johannes Kepler” with the International Space Station planned for 24 February 2011. The laser beams guide the orientation of the coupling as both spaceships synchronize speeds at 27743.8 km/h (ESA, 2011).

Like its predecessor, ATV-1 “Jules Verne” in 2008, the new ATV will collect debris from the Space Station. In a few months it will separate to head towards the Earth in a controlled destructive re-entry over the Pacific Ocean, burning up as it enters our atmosphere.

References

¤ “ATV Johannes Kepler operating flawlessly” (2011). European Space Agency (ESA). [Online]. Available here. (Accessed: 19 February 2011).
¤ “Europe’s ATV Johannes Kepler supply ship on its way to Space Station” (2011). European Space Agency (ESA). [Online]. Available here. (Accessed: 19 February 2011).
¤ “Second ATV named after Johannes Kepler” (2009). European Space Agency (ESA). [Online]. Available here. (Accessed: 19 February 2009).
¤ Thisdell, D. (2011). “Kepler launch marks 42nd straight Ariane 5 success.” Flightglobal [Online]. Available here. (Accessed: 19 February 2011).

Images

¤ All images edited by ren@rt. Source: NASA and ESA.

STARDUST & TEMPEL - THE MORNING AFTER

Our “Date in space” was a success!

Starship “Stardust-NExT” and Comet “Tempel-1” crossed trajectories on Valentine’s day.

The happy news resulted in 72 pictures sent to Earth and plenty of data recorded by NASA’s spacecraft during the encounter.

It all happened shortly after 4:30 GMT. Stardust, travelling at a speed of 10km/sec got as close as 180 km and used its on-board navigation camera to snap a pictures of Tempel-1 every 6 seconds while receiving impacts from particles flying off the comet at 6km/sec. Sensibly, Stardust had adequate protection behind the Nextel blankets of ceramic cloth that form part of its Whipple Shield.

The exploration of Comet Tempel-1 begun with mission “Deep Impact” in 2005, when the first pictures showed most interesting features with bumps and curves on a slender 14km tall body with a diameter of 4km (JPL 2008). Further analysis will determine the changes that occurred after two successive orbits around the sun (perihelion passes).

The images taken yesterday arrived in 2 hours and were carefully processed. The results display amazing images of areas previously unseen, showing banded slopes about 2km wide and circular areas 150m in diameter (JPL 2011).

The mission was successful, fulfilling its objectives and even getting 20km closer than predicted and obtaining valuable data along the way.

Learning about comets is part of a strategy delineated by NASA in 2003:

• To learn how the solar system originated and evolved to its current state.
• To understand how life begins and determine the characteristics of the solar system that led to the origin of life.
• To catalogue and understand the potential impact hazard to Earth from space (NASA-JPL, 2011).

Pictures of the surface of Tempel-1 obtained in 2005 raise a number of questions related to the structure and history of the comet. A number of crater-like structures suggest previous collisions with smaller objects. Closer inspection also reveals smooth areas that may suggest some type of flow, possibly caused by a constant shed of particles from its surface or perhaps eruptions from the interior. Recent images from a different point of view and a new orientation of light reveal new features and allow calculation of depth and confirmation of sizes.

Using the Stardust’s navigation camera provided lower resolution images than the ones taken by the Impactor’s dedicated camera sacrificed in 2005, nevertheless, the pictures are invaluable for recording and measurement purposes.

The animation shows the strike of the Impactor deployed from Deep Impact spacecraft in 2005. Despite its small size, the collision resulted in a spectacular blow due to the high kinetic energy of the impactor (19 Gigajoules, equal to 4.8tons of TNT). This force was the result of the combination of its weight (370kg) and its velocity (10km/sec). Considering the relatively massive volume of the 14km comet, no change in trajectory was expected as a consequence of the impact (JPL 2009).

Although the latest images of the comet are not as sharp, it looks like the impactor not only flattened a 50m wide mound but also created a 150m crater on the surface of Tempel-1. This crater can be seen in the following images marked by a double yellow circle, where the outer line marks the rim and the inner circle delineates its floor. The depth of the crater is still being studied comparing photos from both visits to the comet. The location of the impact can be seen in the insert. Note its relation to the flat area, which can be seen in pictures above, close to a pair of craters believed to be 300m across.

The efficiency of re-using the spacecraft Stardust is unprecedented. The US$ 29million mission is one of the most economical at NASA, producing magnificent results and will continue "chasing comets in space."

References

¤ “Deep Impact - Mission – What did we hope to see” (2008) . NASA-University of Meryland- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 14 February 2011).
¤ “Impactor - Technology” (2009) NASA- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 15 February 2011).
¤ “Stardust – Image Gallery” (2011) NASA [Online]. Available here. (Accessed: 16 February 2011).
¤ “Stardust - Mission and Science Objectives” (2011). NASA- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 15 February 2011).
¤ “Stardust - New Territory on Tempel-1” (2011). NASA- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 15 February 2011).
¤ “Stardust-NExT Mission” (2011). NASA- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 14 February 2011).

Images

¤ All images edited by ren@rt. Source: NASA and JPL.

STARDUST MEETS COMET TEMPEL-1 – 14FEB2011

On Monday 14 February 2011, the Spacecraft Stardust-NExT will encounter Comet Tempel-1, a historical meeting with this comet after a first encounter in 2005.

Scientists believe that the elements that started life on Earth arrived in comets, which are thought to contain water ice, dust and carbon-based compounds. Obtaining further evidence of the presence of these substances directly from a comet in space would strongly support that theory (Yeomans 2008).

Comet Tempel-1 was the subject of mission “Deep Impact” in 2005. In that occasion, an “Impactor” was deployed aiming to strike the comet. As the impactor approached its target, it took close-up pictures of the surface. The cameras of spaceship Deep Impact recorded the collision from a safe distance. The comet continued its trajectory towards the sun.

This time, Stardust-NExT will approach Tempel-1 on its way back from its orbit around the sun hoping to observe changes that might have occurred since 2005, including the man-made crater created by the hit of Deep Impact’s mission.

Stardust was launched by NASA in 1999 and so far it has travelled 5.6million kilometres. Three years after leaving Earth, the spacecraft flew close to Asteroid Annefrank, obtaining valuable data. In 2006 it approached Comet Wild 2 and captured samples of particles shed in its coma. When the spacecraft was close to Earth, it sent those samples in a capsule that landed safely and became a historical landmark; that was the first time scientists examined elements captured from a comet in space.

Late in 2009, the course of Stardust was corrected to target a flyby meeting with Tempel-1. According to plan, one hour before the meeting, the spacecraft will use its camera to target the brightness of the comet and re-align itself automatically. Due to the location of the encounter, at a distance similar to that from Earth to the Sun but on the other side of our star, communications with Stardust take around 40 minutes to arrive to Earth. This delay, together with the limited amount of fuel, makes controlling the mission a real challenge.

This is also the first time a comet is approached by a spacecraft on a second occasion; an invaluable opportunity to obtain new images and study the comet’s coma. Images are expected to arrive to NASA in 2 hours and become available in 12 hours, the time required for processing (JPL, 2011).

Many observatories around the world collaborated in the calculation of the trajectory of the comet. Their findings showed that Tempel-1 is gradually accelerating and probably rotating. Hopefully the calculations will be correct and the meeting will happen despite unpredictable changes of the course of the comet.

WAITING FOR THE BIG MOMENT

Many observatories around the world collaborated in the calculation of the trajectory of the comet. Their findings showed that Tempel-1 is gradually accelerating and probably rotating.

Along its elliptical orbit around the Sun, the comet sheds particles that form its coma. These particles travel at very high speeds (approximately 6km/sec) becoming dangerous projectiles for any object that happens to be on their way.

Stardust was built with a set of protective shields, which proved to be effective during its encounter with Comet Wild-2 in 2004. The image shows an artistic impression of particles hitting the shields. As the model shows, the protection is located at one end of the spaceship; this means that alignment parallel to the trajectory of particles is crucial for the survival of the instruments. It also means that most instruments cannot “see” directly into the comet while it is travelling across the coma.

Despite the risks, the historical mission went ahead and on the night of St. Valentine’s day (14 February 2011), events unfolded as planned. The Space Agency shared the moments with the world via NASA-TV in a live broadcast from mission control in Denver, Colorado (Spacevidcast, 2011).

Below is the list of tasks carried out by Stardust as it crossed the path of comet Tempel-1. A night charged with emotion and expectations that finally brought a smile of satisfaction to everyone, those directly involved in the mission and millions of followers around the world.

References

¤ Live broadcast of Stardust meeting Tempel-1 (2011). Spacevidcast - NASA- JPL [Online]. Available here. (Accessed: 14 February 2011).
¤ “Stardust-NExT: Encounter of Tempel-1, February 14, 2011” (2011). NASA-- Jet Propulsion Laboratory [Online]. Available here. (Accessed: 13 Feb. 2011).
¤ Yeomans, D. (2008). Why Study comets? NASA - Jet Propulsion Laboratory [Online]. Available here. (Accessed: 13 Feb. 2011).

Images

¤ All images edited by ren@rt. Source: NASA and JPL.