Physics Update Course Summer 2013

Visiting the National Space Centre

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The above right picture is of a pressure suit.

Space, skydiving and Red Bull – the Physics behind the Stratos Skydive

Anu Ojha

Director (National Space Academy), National Space Centre

On the 14th October 2012 a global audience held its breath as Felix Baumgartner leapt from 39km above New Mexico and became the first person to break the sound barrier with his body.

What were the physics and engineering challenges he faced in surviving the dynamic conditions he encountered on his plunge through a near-vacuum? Was this just a giant leap for a sports drink’s marketing or a meaningful breakthrough in space/aerospace technology applications?

How can teachers use the engineering challenges encountered during the programme and the data acquired to go beyond “edutainment” and make a meaningful difference to students’ understanding of fundamental concepts in physics?

When an object falls through air it will eventually reach terminal velocity. This occurs when the air resistance acting against the falling object is equal to (but acting in the opposite direction) to the weight of the object. The value of the air resistance or drag force is given by the equation

where ρ is the density of the fluid, v^2 is the square of the speed of the body, A is the area and Cd is the drag coefficient (related to the shape and surface roughness of the body).

The weight of the object is the force due to gravity F = mg, where m is the mass of the body and g is the gravitational acceleration.

For an object falling from the edge of space terminal velocity will be very large due to the thin atmosphere. This because the object will spend a greater time accelerating until the forces become equal. If the object is a living thing then it needs to be protected from the lack of air and the effects of the acceleration if in free fall.

The Karman line, lies at an altitude of 100 kilometres above the Earth’s sea level, and is commonly used to define the boundary between the Earth’s atmosphere and outer space. This definition is accepted by the Fédération Aéronautique Internationale (FAI), which is an international standard setting and record-keeping body for aeronautics and astronautics.

A sub-orbital space flight is a spaceflight in which the spacecraft reaches space, but its trajectory intersects the atmosphere or surface of the gravitating body from which it was launched, so that it does not complete one orbital revolution.

The importance of Felix Baumgartner’s free fall from the edge of space wasn’t just about breaking records but also about the technology involved in keeping people alive at such heights. There are many projects at the moment all with the aim of suborbital space tourism but the problem with these is what to do if something goes wrong. Passengers need to be protected from low oxygen levels, low air pressure and very low temperatures. This would require some form of a pressure suit.

In the video below marshmallows are used to show the effect of reduced air pressure on a living organism. You can imagine the lungs, amongst all the other organs, being badly affected.

The video below shows water boiling at 41 degrees Celsius at reduced pressure. A common misconception is that an unprotected human’s blood would start boiling in the arteries and veins at low pressure, but since the skin is a reasonably good pressure vessel this would not be the case.

However, the dramatic outgassing of nitrogen dissolved in the bloodstream (similar to, but far more rapid than the experiences of divers who ascend too quickly from depth) coupled with the effects of explosive decompression and lack of oxygen would result in unconsciousness in seconds, and death within a minute or two.

Like sky diving, space diving refers to the act of jumping from an aircraft or spacecraft in outer space and falling to Earth’s atmosphere before parachuting to a landing.

Felix Baumgartner wasn’t the first person to attempt the leap from the edge of space. On 16 August 1960 US Air Force test pilot Joe Kittinger jumped from a helium balloon 31,341m (102,800ft) above the deserts of New Mexico and set a free-fall skydiving record until 14th October 2012.

Colonel Joseph William Kittinger II (born July 27, 1928 in Tampa, Florida, United States) is a former USAF Command Pilot, career military officer and retired Colonel in the United States Air Force. He is most famous for his participation in Project Manhigh and Project Excelsior in 1960, setting the record longest skydive from a height greater than 31 kilometres.

As jet planes flew higher and faster in the 1950s, the USAF became increasingly worried about the safety of flight crews who had to eject at high altitude. Tests in Operation High Dive with dummies had shown that a body in free-fall at high altitude would often go into a flat spin at a rate of up to 200 revolutions per minute. This would be potentially fatal. Some of the dummies actually lost limbs.

Project Excelsior was initiated in 1958 to design a parachute system that would allow a safe, controlled descent after a high-altitude ejection.

During Kittenger’s first test, the stabilizer parachute was deployed too soon, catching him around the neck and causing him to spin at 120 revolutions per minute. He lost consciousness, but his life was saved by his main parachute which opened automatically at a height of 3,048 m.

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Above left Kittinger next to the Excelsior gondola.

The video below is about Kittenger’s jump.

The next person to attempt the jump was Yevgeni (Eugene) Nikolayevich Andreyev (September 4, 1926 – February 9, 2000). He was a colonel in the Soviet Air Force.

Andreyev set an official record for the longest distance free-fall parachute jump on 1 November 1962, which the Guinness Book of Records put at 24,500 meters. The record was previously held by Joseph Kittinger, whose jump was for a longer distance, but was stabilized by a drogue parachute. Andreyev was awarded the Hero of the Soviet Union for his feat. The free fall distance record stood for nearly 50 years until broken by Felix Baumgartner in 2012.

A drogue parachute is a parachute designed to be deployed from a rapidly moving object in order to slow the object, or to provide control and stability, or as a pilot parachute to deploy a larger parachute. It was invented by Giovanni Agusta in 1911.


Nicholas John Piantanida (August 15, 1932 – August 29, 1966) was an American amateur parachute jumper who reached 37642 meters, with his Strato Jump II balloon on February 2, 1966, flying a manned balloon higher than anyone before, a record that stood until Felix Baumgartner’s flight on October 14, 2012.

On the morning of May 1, 1966, he began his third ascent for a planned super-sonic free fall from over 120,000 feet. However, during the descent Piantanida’s face mask had depressurized at about the 57,000-foot mark. Ground controllers immediately jettisoned the balloon at close to 56,000 feet (17,000 m) — higher than the cruising altitude for commercial jets — and Piantanida’s gondola parachuted to the ground. Piantanida barely survived the fall, and the lack of oxygen left him brain damaged and in a coma from which he never recovered. Piantanida died four months later at the Veterans Hospital in Philadelphia, on August 29.

Bill Weaver (1930-) was a test pilot and on the 25th of January 1966 he was testing a modified SR-71 Blackbird. While in flight the right engine developed a fault and the plane started to disintegrate. Luckily his pressure suit inflated and his small guide parachute deployed. His inflated pressure suit acted as a sort of escape pod. Unfortunately the man with him, Jim Zwayer, wasn’t so lucky.


Michael James Adams (May 5, 1930 – November 15, 1967) was an American aviator and USAF astronaut. He was the first American space mission fatality, according to the United States definition.

Adams’ seventh X-15 flight, Flight 3-65-97, took place on 15 November 1967. He reached a peak altitude of 81 km; the nose of the aircraft was off heading by 15 degrees to the right. While descending, at 70 km the aircraft encountered rapidly increasing aerodynamic pressure which impinged on the airframe, causing the X-15 to enter a violent Mach 5 spin. As the X-15 neared 20 km, it was diving at Mach 3.93 and experiencing more than 15-g vertically (positive and negative), and 8-g laterally, which inevitably exceeded the design limits of the aircraft. The aircraft broke up 10 minutes and 35 seconds after launch, killing Adams. The United States Air Force posthumously awarded him Astronaut Wings for his last flight.


The purpose of the Red Bull Stratos mission was to transcend human limits. Supported by a team of experts Felix Baumgartner ascended to 128,100 feet in a stratospheric balloon and made a freefall jump rushing toward earth at supersonic speeds before parachuting to the ground. His successful feat on October 14, 2012 holds the potential to provide valuable medical and scientific research data for future pioneers.

Felix Baumgartner (born 20 April 1969) is an Austrian skydiver, daredevil and BASE jumper. He set the world record for skydiving an estimated 39 kilometres, reaching an estimated speed of 1357.64 km/h, or Mach 1.25, on 14 October 2012, and became the first person to break the sound barrier without vehicular power on his descent. He is also renowned for the particularly dangerous nature of the stunts he has performed during his career. Baumgartner spent time in the Austrian military where he practiced parachute jumping, including training to land on small target zones.

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Below is the link to a compilation video of the descent.

In the physics classroom Felix Baumgartner’s exploits can be used to produce distance-time graphs and velocity-time graphs to analyse how his motion changed during descent.

Tracking software can be used to analyse the video of the descent.

The forces experienced by Felix can be calculated.

Calculations involving the gas laws.

Mars Curiosity Rover

Dr John Bridges

Reader in Planetary Science University of Leicester

Unfortunately Dr Bridges wasn’t able to give his lecture but you can find information about his work on the Mars Curiosity Rover by clicking on the links above.

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