Felix Baumgartner’s supersonic freefall from the edge of space on 14 October 2012, reached an even faster speed than originally estimated: Mach 1.25. The statistic was just part of the news shared in a report detailing the results of a three-month-long analysis of mission data conducted by the Red Bull Stratos science team.
The wide-ranging science findings, including the first physiologic data ever captured from a human freefalling faster than the speed of sound, also led to some revisions in the initial figures from the jump, which collected knowledge for future aerospace travel while breaking numerous records. Baumgartner’s record-breaking maximum vertical speed was revised upwards to 1 357,6 km/h / Mach 1.25 from an initial estimate of 1 342,8 km/h / Mach 1.24. With the help of additional data recorder analysis, the jump altitude was revised slightly down to 38 969,4 m from the previous estimate of 39 045 m.
The most important finding of the mission’s analysis was already abundantly evident to the countless millions of viewers who watched the leap live around the world. The Austrian adventurer’s freefall demonstrated that, with the right equipment and proper training, a human being can safely accelerate through the sound barrier. That is a vital breakthrough for the aerospace industry as it looks for answers to the questions of crew and passenger escape in emergency situations, especially with commercial space travel on the horizon.
“Together we proved that a human in freefall can break the speed of sound returning from near space, going through a transonic phase and landing safely on the ground,” said Dr Jonathan Clark, Red Bull Stratos Medical Director. “That was a big part of the programme, and monitoring the mission was a meaningful event in aerospace medicine and physiology.”
The documentation was finalised after the mission’s science team conducted a private peer review, the Red Bull Stratos Scientific Summit, at the California Science Centre on 23 January 2013, where the attendees included Nasa astronauts, US Air Force officers, and representatives from commercial aerospace companies such as Virgin Galactic, Northrop Grumman, SpaceX, XCOR, Sierra Nevada Corporation and more. Also revealed were the final figures submitted for records approval – including the slight upward revision in Baumgartner’s supersonic speed.
Red Bull Stratos was a historic mission to the edge of space in which Baumgartner, a professional BASE jumper, fulfilled a lifelong dream: jumping from a capsule that had ascended 39 kilometres above Earth, attached to a helium balloon. He became the first human to break the sound barrier in freefall and established numerous additional records in the process. From its inception, the mission was envisioned as a flight test program for medical and scientific advancement in human flight.
The release of findings from the mission is the culmination of five years of active flight test programme development, and topics range from technical breakthroughs to medicine and meteorology. Some the most eagerly awaited information was Baumgartner’s preliminary physiologic data, which includes heart and respiratory rate at key points during the ascent and record-breaking freefall back to Earth.
Baumgartner’s physiologic monitoring provided the team with more than 100 million data points – including the first physiologic data ever gathered from a human travelling at supersonic velocity. The newly released data not only includes his heart and respiratory rate, but also indicates the forces he encountered at milestones throughout the mission.
Baumgartner’s heartbeat reached a maximum of 185 beats per minute (bpm) when he exited the capsule and ranged from 155 to 175 bpm during freefall. Baumgartner, whose heartbeat during the pre-launch oxygen pre-breathe period was 40 to 100 bpm, had a heartbeat of 60 to 100 bpm during the ascent and 169 bpm when he hit Mach. 1.25 on the way back to Earth, 155 to 180 during the parachute descent, 163 upon landing and 100 as the recovery helicopter flew him back to Mission Control. His respiratory rate hit a maximum of 30 to 43 breaths per minute during the freefall.
Baumgartner experienced 25,2 seconds of absolute weightlessness during the initial stage of his freefall. Subsequently, he entered a period of turning and spinning that reached a maximum rate of 60 revolutions per minute and put the 43-year-old in a “flat spin” position for about 13 seconds He was able to stabilise his trajectory using his skydiving skills. All physiologic data were well within anticipated parameters, never exceeding safety margins. (For example, the G meter worn on Baumgartner’s wrist never experienced the 6 continuous seconds at 3.5 G that would have triggered deployment of his stabilisation parachute; in fact the area of most concern, Baumgartner’s cranial region, remained under 2 G for the duration of his spin.)
Baumgartner described the freefall sensation as he accelerated to and through the sound barrier: “It feels like you are floating into space, and then you pick up speed very fast – but you don’t feel the air because the air density is so low. For almost 35 seconds I couldn’t sense the air around me because basically there was none. That kind of helpless feeling is annoying as a professional skydiver. And then when you finally enter a thicker air layer you have to keep yourself completely symmetrical because otherwise you start spinning, which is what happened to me.”
Space suit and parachute
The mission achieved many science innovation milestones such as: the development and validation of pressure suit and personal parachute rig innovations; the development of new medical treatment protocols, including a protocol for the condition of embolism anticipated to become the new standard of care; and the introduction of a “reefed” parachute system to the task of high-altitude payload recovery, offering potential benefits for both passengers and cargo.
Baumgartner’s space suit was custom designed to provide the mobility necessary for controlled freefall, as well as modifications to enhance visual acuity, GPS tracking and thermal protection. “He could have gone to the Moon in that suit, but yet he was also able to fall in a head-down position and be comfortable inside it,” said Mike Todd, the life support engineer from Sage Cheshire Aerospace who personally dressed Baumgartner for every jump.
Following weeks of post-mission analysis, Brian Utley, Official Observer for the Contest and Records Board of the United States’ National Aeronautic Association, was able to provide updates to the World Record figures currently under review for confirmation by the Fédération Aéronautique Internationale governing body (a process that typically requires an extended timeframe):
Maximum Vertical Speed: * 1 357,6 km/h / Mach 1.25
Previous estimate: 1 342,8 km/h / Mach 1.24
Highest Exit (Jump) Altitude: 38 969,4 m
Previous estimate: 39 045 m
Vertical Freefall Distance: * 36 402,6 m
Previous estimate: 36 529 m
*without drogue or stabilization device
Utley pointed out that Baumgartner’s jump altitude was a “quantum” 24-per cent higher than the previously known highest exit altitude, Joe Kittinger’s 1960 jump from 31 333 metres. He also reconfirmed Baumgartner’s originally stated freefall time: 4 minutes, 20 seconds, and noted that Baumgartner’s balloon reached a peak altitude of 39 068,5 metres, the highest manned ascent known, before descending slightly as the Austrian prepared to jump.
Utley pointed out that the Maximum Vertical Speed category is a new one for the FAI, established especially to accommodate the groundbreaking nature of the Red Bull Stratos program.
The Red Bull Stratos team continues to analyse deeper layers of data, with results to be shared in venues such as journal publications and conferences. But the true legacy of the mission will become apparent as new projects and programs take inspiration from the information provided by Baumgartner’s mission to make pioneering efforts of their own.