Red Bull Stratos was a privately funded high-altitude balloon program that combined aerospace research with a human freefall mission from the stratosphere. The project originated in 2005 when Austrian skydiver and BASE jumper Felix Baumgartner discussed with aerospace engineer Art Thompson the possibility of exceeding the altitude reached by Joseph W. Kittinger during Project Excelsior in 1960. Early studies considered both a balloon capsule and a rocket-powered spacecraft. The spacecraft concept was abandoned because of its cost, complexity, certification requirements and crew escape issues. The team selected a zero-pressure helium balloon and a pressurized capsule as the safest and most practical solution for reaching about 36.6 km (120,000 ft).

Development began in 2007 under Red Bull sponsorship. Progress was interrupted in 2010 by legal disputes over intellectual property, delaying the program for almost two years. During this period the engineering team refined the flight systems, operational procedures and human factors program before flight testing resumed.

The primary objective was to demonstrate that a person could safely ascend beneath a helium balloon to the upper stratosphere and perform a controlled freefall while collecting biomedical and engineering data relevant to future high-altitude escape systems. The mission also evaluated pressure suits, life-support equipment, capsule systems, communications, telemetry and recovery procedures under near-space conditions.

Another objective was to improve knowledge of human performance during transonic freefall. Project Excelsior had been limited by the instrumentation available in 1960. Red Bull Stratos employed modern sensors to measure acceleration, body attitude, suit performance, physiological parameters and environmental conditions throughout the mission.

The project also sought Fédération Aéronautique Internationale records for highest manned balloon flight, highest parachute jump, longest freefall distance and first supersonic freefall without mechanical propulsion. Although these records attracted public attention, the project emphasized its engineering and research objectives.

The program was financed by Red Bull and managed through Red Bull Stratos LLC. Engineering development was directed by Sage Cheshire Aerospace under Mission Director Art Thompson. Program management was led by Marle Hewett, a former U.S. Navy commander and NASA flight test engineer. Operations brought together specialists in aerospace engineering, medicine, meteorology, communications, ballooning and parachute systems.

Felix Baumgartner served as test subject and mission pilot. Retired U.S. Air Force Colonel Joseph W. Kittinger, who performed the Project Excelsior III jump in 1960, served as technical adviser, capsule communicator and mentor. His experience influenced emergency procedures, freefall stabilization and mission planning.

Flight surgeon Jonathan Clark directed the biomedical program, developing medical protocols, physiological monitoring and emergency procedures. Meteorologist Don Day was responsible for launch weather analysis. Jay Nemeth supervised imaging systems, Riedel Communications developed the communications architecture, and balloon operations were conducted by an ATA Aerospace launch crew led by Ed Coca.

Specialized suppliers produced the pressure suit, capsule, electronics, telemetry, environmental control systems and recovery equipment. Most hardware adapted existing aerospace technology instead of developing new space-qualified systems.

The flight system consisted of a helium balloon, pressurized capsule, pressure suit, life-support equipment, parachute system and ground control infrastructure.

The zero-pressure helium balloons used in the different missions of the project were manufactured from thin polyethylene film by India’s Tata Institute of Fundamenteal Research and Raven Aerostar, measured about 170 m in length at launch while only partially inflated. During ascent it expanded to a sphere about 120 m in diameter containing approximately 850,000 m³ of helium. Inflation required calm winds and a carefully coordinated launch sequence using cranes, restraints and weather balloons to stabilize the envelope.

The pressurized capsule was the most complex component. A spherical fiberglass pressure vessel was selected for its structural efficiency and thermal stability. The cabin maintained an internal pressure of about 0.55 atm throughout ascent while external pressure approached near-vacuum conditions. A steel frame supported batteries, gas cylinders, telemetry equipment and parachute attachments, while crushable landing structures beneath the pressure vessel absorbed landing loads.

The cockpit emphasized redundancy and manual control. About eighty circuit breakers allowed individual systems to be isolated, and communications, environmental controls, balloon systems and telemetry could all be operated manually. Ergonomic studies using full-scale mockups ensured Baumgartner could perform all required tasks while wearing a pressurized suit. The exit sequence required more than thirty actions before leaving the capsule.

The pressure suit functioned as an individual life-support system. Derived from aerospace pressure-suit technology, it provided pressure, oxygen and thermal protection during ascent and freefall. Baumgartner breathed pure oxygen before launch to reduce decompression sickness risk. Suit qualification included repeated altitude chamber tests simulating mission conditions. During development Baumgartner experienced claustrophobia and anxiety while wearing the suit, requiring a dedicated psychological training program.

The capsule carried multiple high-definition, still and high-speed cameras mounted inside and outside the vehicle. The equipment was modified for operation in near-vacuum conditions through specialized electronics, solid-state storage, nitrogen-filled housings and thermal management. The system recorded several terabytes of data while transmitting live video to Mission Control.

Following two unmanned qualification flights and two manned test jumps from 21,818 m and 29,456 m in 2012, the final mission launched from Roswell, New Mexico, on 14 October 2012. The balloons used for the unmanned qualification flights were supplied by the Tata Institute of Fundamental Research (TIFR) of India, while the manned flights employed the full-scale Raven Aerostar balloon developed for the final mission. Baumgartner reached 38,969 m (127,852 ft), exceeding the planned altitude. After depressurizing the capsule he entered freefall and accelerated to Mach 1.25 (1,357.6 km/h), becoming the first person to exceed the speed of sound in freefall without mechanical propulsion. A brief flat spin developed shortly after exit before aerodynamic stabilization occurred. He landed safely in eastern New Mexico.

The mission established new world records for highest manned balloon flight, highest parachute jump and first supersonic freefall. The longest freefall record was surpassed by Alan Eustace as part of Stratex project in 2014.

Red Bull Stratos also demonstrated the value of corporate sponsorship in aerospace projects and became a milestone in science communication. Red Bull documented the engineering, training and flight campaign through documentaries, web content and printed publications. The final mission was broadcast live through YouTube and television networks. More than eight million viewers watched simultaneously on YouTube, setting a platform record at the time, while total television and online audiences reached tens of millions, making the mission one of the most widely viewed live aerospace events of the early twenty-first century.

Launch base	Date	Flight Duration	Experiment	Payload landing place or cause of the failure
Roswell (NM)	12/15/2011	---	RED BULL STRATOS - Unmanned test - POD	Balloon failure at launch
Roswell (NM)	12/16/2011	---	RED BULL STRATOS - Unmanned test - POD	--- No Data ---
Roswell (NM)	1/18/2012	---	RED BULL STRATOS - Unmanned test - POD	--- No Data ---
Roswell (NM)	3/13/2012	---	RED BULL STRATOS I - (Baumgartner)	Balloon failure at launch
Roswell (NM)	3/15/2012	---	RED BULL STRATOS I - (Baumgartner)	20 miles E of Roswell, New Mexico, US
Roswell (NM)	7/25/2012	---	RED BULL STRATOS II - (Baumgartner)	Near Roswell, New Mexico, US
Roswell (NM)	10/9/2012	---	RED BULL STRATOS III - Sonde	--- No Data ---
Roswell (NM)	10/9/2012	---	RED BULL STRATOS III - (Baumgartner)	Ground Abort. Balloon destroyed by a gust of wind during inflation
Roswell (NM)	10/14/2012	---	RED BULL STRATOS III - Sonde	--- No Data ---
Roswell (NM)	10/14/2012	---	RED BULL STRATOS III - (Baumgartner)	37 miles E of Roswell, New Mexico, US