Tim Peake: How the UK astronaut gets to space and back

UK astronaut Tim Peake will travel to the International Space Station (ISS) on 15 December. Since the space shuttle's retirement, the Russian Soyuz launch system is now the only way for crew members to get to the ISS.

The basic design for the Soyuz capsule was laid down as far back as the 1960s. It was originally intended to serve as the craft that would carry cosmonauts to the Moon.

When the US beat them to the lunar surface in 1969, the USSR's lunar programme was scrapped. But the Soyuz was retained, and became the Soviet - and subsequently Russian - vehicle of choice for launching humans to low-Earth orbit.

It was the craft that carried the first crew to the International Space Station in 2000, and has been the only craft ferrying humans to the orbiting outpost since the retirement of the US space shuttle in 2011.

"International Space Station after undocking of STS-132" by NASA/Crew of STS-132 -Licensed under Public Domain via Commons 

The current version, known as the Soyuz-TMA, can transport up to three cosmonauts and a limited amount of cargo to and from the ISS. At least one Soyuz is docked to the space station at all times to be used as a lifeboat in an emergency.

At one end of the spacecraft is the spherical orbital module. It's about the size of a large van and provides extra living space for the crew during flight. It can be used to store supplies and other cargo, such as experiments, and there's also a toilet.

The orbital module contains the mechanism used to dock with the space station and the hatch that allows crew members to enter the ISS.

The craft's mid-section is known as the descent module, and is where crew members sit during launch and the journey back to Earth. It contains the spacecraft's controls and displays, including a periscope that allows the crew to see the docking target on the ISS.

The seats have custom-fitted liners, individually moulded to each person's body. This is designed to help cushion the crew members when they land on Earth after a mission.

The third module is known as the instrument module. It contains the thrusters, oxygen and propellant tanks, communications equipment and the onboard computer.

Launched from Baikonur Cosmodrome in Kazakhstan, the 50m-high launcher consists of three sections, or stages. The first stage consists of four identical liquid-booster rockets. These are strapped around the core, or second, stage. The third, or upper, stage carries the Soyuz spacecraft.

The vehicle uses refined kerosene and liquid oxygen as fuel and can deliver payloads of more than seven tonnes - about the weight of a small lorry - into orbit.

Crew members enter the spacecraft two-and-a-half hours before launch to prepare it. At T-minus zero, the four boosters and core engine ignite, propelling the rocket into the air. About two minutes into the flight, the four booster rockets are jettisoned.

The core stage keeps firing, until it too separates at about 4 minutes 48 seconds after launch. A third stage engine then propels the Soyuz to its desired orbit at an altitude of some 220km. During the nine-minute sequence, crew members have to withstand forces up to three-and-a-half times their bodyweight.

The spacecraft then has to perform five engine burns in order to catch up with the ISS. This generally takes six hours, but if things don't go as planned, mission control may decide to fall back to an alternative two-day transfer mode.

Rendezvous and docking with the space station is automated by the onboard computer. It keeps track of the positions of the Soyuz and ISS using measurements from mission control and a radar system called Kurs. However, crew members closely monitor the process and have the ability to intervene or take over manual control if required.

During the final approach, a docking probe on the end of the Soyuz inserts into a cone on the ISS. Once "capture" is confirmed, the docking probe retracts, bringing the two vehicles together. A series of hooks and latches then close over, securing the Russian capsule to the ISS.

Once a tight seal is confirmed, the air pressure in the Soyuz is equalised with that of the ISS and the hatch is opened, so the new arrivals can enter the station.

When crew members are ready to return to Earth, a command is given to start opening the hooks and latches that hold the Soyuz to the ISS. The spacecraft then separates from the space station at a graceful speed of 10cm/s (4ins/s). Once the Soyuz has reached a distance of 20m (66ft) the Soyuz fires its thrusters for 15 seconds.

When the capsule reaches a distance of 19km (12mi) from the ISS, the Soyuz makes its main "de-orbit burn", firing the engines for 4 minutes, 21 seconds to begin the return to Earth. The descent module carrying the crew separates from the empty orbital module which burns up in the atmosphere.

About 15 minutes before landing, the capsule deploys a drogue parachute to slow its descent speed from 230m/s (755 ft/s) to 80m/s (262 ft/s). The main parachute is then released, cutting the capsule's speed to 7 m/s (24ft/s) and shifting it to a vertical position.

Six engines fire on the underside of the capsule to cushion the craft just before it thuds down on the Kazakh steppe.

A recovery and rescue team then arrives to extract the crew members.

For more information visit:-

http://www.bbc.co.uk/news/science-environment-34727773

https://www.prlabs.co.uk/lab-supplies.php?N=oxygen-emptied-cylinder&Id=60499

Liquid water flows on today's Mars: NASA confirms evidence

New findings from NASA's Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars.

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times.

Martian slopes. Credit: NASA/JPL-Caltech/Univ. of Arizona

"Our quest on Mars has been to 'follow the water,' in our search for life in the universe, and now we have convincing science that validates what we've long suspected," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "This is a significant development, as it appears to confirm that water -- albeit briny -- is flowing today on the surface of Mars."

These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it's likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.

"We found the hydrated salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration. In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks," said Lujendra Ojha of the Georgia Institute of Technology (Georgia Tech) in Atlanta, lead author of a report on these findings published Sept. 28 by Nature Geoscience.

Ojha first noticed these puzzling features as a University of Arizona undergraduate student in 2010, using images from the MRO's High Resolution Imaging Science Experiment (HiRISE). HiRISE observations now have documented RSL at dozens of sites on Mars. The new study pairs HiRISE observations with mineral mapping by MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).

The spectrometer observations show signatures of hydrated salts at multiple RSL locations, but only when the dark features were relatively wide. When the researchers looked at the same locations and RSL weren't as extensive, they detected no hydrated salt.

Ojha and his co-authors interpret the spectral signatures as caused by hydrated minerals called perchlorates. The hydrated salts most consistent with the chemical signatures are likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate. Some perchlorates have been shown to keep liquids from freezing even when conditions are as cold as minus 94 degrees Fahrenheit (minus 70 Celsius). On Earth, naturally produced perchlorates are concentrated in deserts, and some types of perchlorates can be used as rocket propellant.

Perchlorates have previously been seen on Mars. NASA's Phoenix lander and Curiosity rover both found them in the planet's soil, and some scientists believe that the Viking missions in the 1970s measured signatures of these salts. However, this study of RSL detected perchlorates, now in hydrated form, in different areas than those explored by the landers. This also is the first time perchlorates have been identified from orbit.

MRO has been examining Mars since 2006 with its six science instruments.

"The ability of MRO to observe for multiple Mars years with a payload able to see the fine detail of these features has enabled findings such as these: first identifying the puzzling seasonal streaks and now making a big step towards explaining what they are," said Rich Zurek, MRO project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

For Ojha, the new findings are more proof that the mysterious lines he first saw darkening Martian slopes five years ago are, indeed, present-day water.

"When most people talk about water on Mars, they're usually talking about ancient water or frozen water," he said. "Now we know there's more to the story. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for RSL."

The discovery is the latest of many breakthroughs by NASA's Mars missions.

"It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington. "It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future."

For more information visit:-

http://www.sciencedaily.com/releases/2015/09/150928094114.htm

https://www.prlabs.co.uk/lab-supplies.php?N=regeneration-salt&Id=62072

Back in 1984

On this day in 1984....

The first untethered spacewalk was made by American Bruce McCandless II on February 7, 1984, during Challenger mission STS-41-B, utilising the Manned Maneuvering Unit. He was subsequently joined by Robert L. Stewart during the 5 hour 55 minute spacewalk. Such a self-contained spacewalk was first attempted by Eugene Cernan in 1966 on Gemini 9A, but Cernan could not reach the maneuvering unit without tiring.

Untethered U.S. astronaut Bruce McCandless uses a manned maneuvering unit. photo taken by Robert "Hoot" Gibson

The Manned Maneuvering Unit (MMU) is an astronaut propulsion unit that was used by NASA on three Space Shuttle missions in 1984. The MMU allowed the astronauts to perform untethered EVA spacewalks at a distance from the shuttle. The MMU was used in practice to retrieve a pair of faulty communications satellites, Westar VI and Palapa B2. Following the third mission the unit was retired from use. A smaller successor, the Simplified Aid for EVA Rescue (SAFER), was first flown in 1994, and is intended for emergency use only.

While orbiting around the Earth at a speed of 17,500 miles per hour, McCandless floated from the cargo bay into outer space, 150 nautical miles above Earth, an experience he described as "a heck of a big leap." Mission specialist Robert L. Stewart, an Army lieutenant colonel, also flew the MMU on shuttle mission 41-B.

While flying the MMU, these men were in a journalistic phrase of the time "human satellites." They checked out the equipment, maneuvered within the cargo bay, flew away from and back to the orbiter, performed docking exercises, recharged the MMU nitrogen tanks, and collected engineering data. The MMU, according to Martin Marietta's post mission report, "performed as expected and no anomalies were reported.

Gaseous nitrogen was used as the propellant for the MMU. Two aluminium tanks with Kevlar wrappings contained 5.9 kilograms of nitrogen each, enough propellant for a six-hour EVA depending on the amount of manoeuvring done. Typical MMU delta-v (velocity change) capability was about 80 feet per second (24.4 m/s).

There were 24 nozzle thrusters placed at different locations on the MMU. To operate the propulsion system, the astronaut used his fingertips to manipulate hand controllers at the ends of the MMU's two arms. The right controller produced rotational acceleration for roll, pitch, and yaw. The left controller produced translational acceleration for moving forward-back, up-down, and left-right. Coordination of the two controllers produced intricate movements in the unit. Once a desired orientation was achieved, the astronaut could engage an automatic attitude-hold function that maintained the inertial attitude of the unit in flight. This freed both hands for work.

Yet the MMU has not been used since 1984. There are several reasons for this. First, most extravehicular activities were effective without use of the MMU. Tethers, safety grips, hand bars, and other restraints allowed astronauts to work in the open cargo bay. Furthermore, the maneuverability of the Space Shuttle itself and the utility of the shuttle's robotic manipulator arm had proved capable of rescuing satellites-the primary function for which the MMU had been designed.



For more information visit:-
http://history.nasa.gov/SP-4219/Chapter13.html
http://en.wikipedia.org/wiki/Manned_Maneuvering_Unit