For generations of astronauts, engineers, and researchers, the path to space has included a rite of passage that is equal parts scientific preparation and surreal thrill ride: floating weightless inside an aircraft diving through the sky. Long before a rocket ever leaves the launchpad, NASA astronauts experience microgravity aboard specially modified jets that fly a series of steep parabolic arcs, briefly creating the same sensation of weightlessness they will encounter in orbit.
These flights — evocatively nicknamed the “Vomit Comet” — have been a cornerstone of spaceflight training and research for nearly 70 years. But now, NASA is signaling that the future of zero-gravity access may look very different from its storied past.
A newly issued contract solicitation from NASA’s Armstrong Flight Research Center, supporting the agency’s Flight Opportunities Program, invites industry to propose innovative new approaches to delivering reduced-gravity and microgravity environments. While parabolic flights remain the gold standard, NASA is explicitly encouraging companies to think beyond the traditional aircraft platforms that have defined the program for decades.
The move opens the door to business jets, experimental aircraft, supersonic platforms, autonomous systems, and other unconventional solutions — potentially reshaping how scientists, engineers, and astronauts access weightlessness on Earth.
Microgravity training before launch is not merely a spectacle. It is a critical component of astronaut readiness.
In orbit, astronauts must maneuver, conduct experiments, operate tools, and manage emergencies without the benefit of gravity. Even simple tasks — drinking water, fastening equipment, or orienting one’s body — behave differently in weightlessness. Parabolic flights allow astronauts to rehearse these realities in a controlled environment before committing to space.
The aircraft achieves this by climbing steeply at roughly a 45-degree angle, then pitching over the top of the arc into a ballistic trajectory. During the crest of the parabola, both the aircraft and everything inside it are in freefall. For about 20 to 30 seconds, occupants float.
Then gravity returns — often abruptly.
During a typical flight, passengers experience approximately 1.8 times Earth’s gravity during the pull-up and pull-out phases before entering the near-weightless portion. The alternating forces can be physically taxing, giving rise to the aircraft’s enduring nickname.
But the value extends far beyond astronaut training. These flights provide one of the few accessible means of conducting short-duration microgravity experiments without going to space.
From fluid dynamics and combustion studies to biomedical research and hardware testing, parabolic flights serve as an intermediate step between laboratory simulations and orbital deployment.
Since the late 2000s, NASA has relied on a single commercial provider to conduct parabolic flights: Zero Gravity Corporation, better known as Zero-G.
Based in Florida, Zero-G operates a retrofitted Boeing 727-200 named G-Force One. During a standard 90-minute flight, the aircraft climbs to roughly 24,000 feet before beginning its parabolic maneuvers, peaking around 32,000 feet.
Each flight typically includes 15 parabolas, offering passengers a cumulative several minutes of weightlessness divided into short intervals. The company provides specialized research flights for NASA and private industry, while also offering commercial experiences to the public.
For $8,900 per person — or $295,000 to charter the entire 28-seat aircraft — civilians aged eight and older can experience weightlessness. The aircraft has also supported television productions and feature films, backed by an in-house production director.
In 2021, NASA awarded Zero-G a five-year Indefinite Delivery, Indefinite-Quantity contract valued at $7.5 million, formalizing a partnership that had already spanned more than a decade.
Zero-G says it remains the only FAA-approved provider of parabolic flights in the United States.
Yet NASA’s latest solicitation suggests that exclusivity may not endure indefinitely.
The history of NASA’s “Vomit Comet” stretches back to the dawn of the space age.
In 1957, the U.S. Air Force began using a Convair C-131 Samaritan — originally designed for VIP transport and medical evacuation — to simulate zero gravity. NASA assumed responsibility for the program in 1973 as the agency expanded its human spaceflight operations.
Eventually, the role shifted to a Boeing KC-135 Stratotanker, a military aerial refueling aircraft. The KC-135 variant used for parabolic flight became iconic, executing tens of thousands of parabolas over its service life.
One aircraft reportedly flew more than 58,000 parabolic arcs and even supported filming for the Hollywood blockbuster Apollo 13, allowing actors to float authentically in microgravity.
But maintaining a unique, aging aircraft solely for parabolic missions proved increasingly difficult. The KC-135 was retired from NASA service in 2004. A C-9B (a modified DC-9) succeeded it for about a decade before also being phased out.
By the mid-2010s, parabolic flight responsibilities had transitioned entirely to the private sector.
NASA’s renewed call for competitors may reflect lessons learned from recent disruptions.
During the height of the COVID-19 pandemic in 2020, Zero-G temporarily suspended operations. In 2022, G-Force One was sidelined for a period due to unspecified equipment issues. Air Force Academy cadets expecting a zero-gravity experience had their plans replaced with scuba diving exercises instead.
Such interruptions underscore the vulnerability of relying on a single aircraft platform — particularly one based on the increasingly rare Boeing 727.
As commercial 727s disappear from service worldwide, sourcing spare parts and maintaining airworthiness becomes progressively more complex and costly. Over time, these challenges could limit availability or increase prices.
NASA’s solicitation appears designed to diversify risk while potentially improving performance and expanding capability.
The new request for information does not mandate adherence to legacy platforms. Instead, it invites “innovative approaches” to delivering parabolic flight services.
Eligible contractors must demonstrate the ability to simulate multiple gravity conditions in a single flight — including microgravity, lunar gravity (approximately one-sixth of Earth’s gravity), and Martian gravity (about one-third of Earth’s gravity). Each condition must be sustained for at least 10 seconds, with 30 seconds or longer preferred.
NASA acknowledges that different missions may prioritize different parameters.
In some cases, maximizing the duration of weightlessness may be more important than precision — particularly for experiential flights. In others, strict accuracy and stability of gravitational levels may be critical for sensitive payloads.
Importantly, NASA notes that many payloads will require human tending. While autonomous systems are mentioned as possibilities, fully unmanned platforms may not be sufficient for all research needs.
Still, the openness to alternative systems hints at potential transformation.
High-performance business jets could theoretically deliver steeper climbs and longer ballistic arcs than older commercial airliners. Supersonic aircraft, if certified and properly configured, might expand performance envelopes further.
Meanwhile, unmanned aerial systems are emerging as viable tools for specialized microgravity research.
In 2023, British company Gravitilab demonstrated a drone-based microgravity experiment using a modified quadcopter to conduct a 2,000-foot drop test. The system created brief periods of weightlessness for onboard payloads, potentially lowering the barrier to entry for small-scale experiments.
Such approaches cannot yet replicate the duration of traditional parabolic flights, but they illustrate how new technology could complement or partially replace existing methods.
Lower-cost platforms could democratize microgravity research, enabling universities, startups, and small businesses to test hardware without the expense of chartering large aircraft.
While Zero-G currently dominates the U.S. market, Europe offers multiple alternatives.
France’s Novespace, a subsidiary of the French Space Agency, operates an Airbus A310 for parabolic flights serving researchers and private participants. In the United Kingdom, startup Blue Abyss has announced ambitions to provide similar services using a modified Boeing 757.
Blue Abyss recently broke ground on a large space training facility in Brook Park, Ohio, partnering with NASA on aspects of its development. The company has signaled intentions to expand into parabolic flight operations, potentially positioning itself as a direct competitor in the U.S. market.
If international firms establish American operations, NASA’s diversification goals could align with broader commercial expansion.
The solicitation falls under NASA’s Flight Opportunities Program, which aims to accelerate the development of space technologies by providing suborbital test environments.
Microgravity testing is often a key milestone in raising a technology’s readiness level before it qualifies for spaceflight.
Hardware designed for lunar missions, Mars expeditions, or orbital platforms must function reliably in reduced gravity. Parabolic flights provide an affordable, repeatable testing ground before committing to launch.
By encouraging flexible and scalable operational concepts, NASA appears to be seeking more than just redundancy. The agency may be aiming to expand access, reduce costs, and increase flight frequency.
If successful, the initiative could enable more researchers to test payloads more often, shortening development cycles.
NASA’s dual mission — supporting serious research while fostering experiential training — presents unique requirements.
For astronauts, precision matters. The gravitational profile must match expectations, and safety margins must be uncompromising.
For educational or outreach flights, longer periods of low gravity might be preferable, even if precision is less stringent.
Future providers may specialize in distinct niches, with some platforms optimized for high-accuracy research and others tailored for extended experiential exposure.
Such specialization could mirror broader trends in commercial spaceflight, where diverse providers address varied segments of the market.
NASA’s solicitation remains open through March 2, and the agency has not indicated when a new contract might be awarded.
Zero-G continues to operate G-Force One and maintains its FAA approval. The company’s track record — including more than 2,300 research parabolas flown for NASA as of 2025 — positions it strongly for continued partnership.
But the competitive landscape may soon evolve.
If business jets, experimental aircraft, or autonomous systems can demonstrate improved performance, lower costs, or greater flexibility, NASA’s decades-old approach to simulating space on Earth could enter a new era.
Despite technological shifts, one constant remains: the profound impact of experiencing weightlessness.
Astronauts often describe their first moments of floating as transformative — a visceral reminder that they are leaving Earth’s familiar constraints behind.
For researchers, those fleeting seconds can reveal behaviors that no Earth-bound simulation can fully replicate.
For civilians fortunate enough to afford it, parabolic flights offer a glimpse of the extraordinary — a brief departure from gravity’s grip.
NASA’s latest move suggests that while the “Vomit Comet” nickname may endure, the aircraft delivering the experience may soon change.
After nearly seven decades of parabolic flight, the next generation of zero-gravity providers could redefine how humanity rehearses for space — not by abandoning tradition, but by expanding it.
As the commercial space sector matures and new aerospace technologies emerge, access to microgravity may become more flexible, more scalable, and more innovative than ever before.
And somewhere above 30,000 feet, another aircraft — perhaps sleeker, faster, or even unmanned — may soon trace the familiar arc that turns sky into orbit, if only for 30 seconds at a time.
