NASA Astronomy Picture of the Day

Apr 28 2023

Runaway Star Alpha Camelopardalis

Like a ship plowing through cosmic seas, runaway star Alpha Camelopardalis has produced this graceful arcing bow wave or bow shock. The massive supergiant star moves at over 60 kilometers per second through space, compressing the interstellar material in its path. At the center of this nearly 6 degree wide view, Alpha Cam is about 25-30 times as massive as the Sun, 5 times hotter (30,000 kelvins), and over 500,000 times brighter. About 4,000 light-years away in the long-necked constellation Camelopardalis, the star also produces a strong stellar wind. Alpha Cam's bow shock stands off about 10 light-years from the star itself. What set this star in motion? Astronomers have long thought that Alpha Cam was flung out of a nearby cluster of young hot stars due to gravitational interactions with other cluster members or perhaps by the supernova explosion of a massive companion star.

https://apod.nasa.gov/apod/astropix.html?

NASA’s Quesst: Reassessing a 50-Year Supersonic Speed Limit

Apr 27 2023

Fifty years ago, the federal government banned all civilian supersonic flights over land.

The rule prohibits non-military aircraft from flying faster than sound so their resulting sonic booms won’t startle the public below or concern them about potential property damage.

Officially put into effect on April 27, 1973, the ban’s introduction was strongly influenced by public opinion surveys in cities where supersonic military jets were flown overhead, and many folks said they didn’t like what they heard or the way their windows rattled because of the sonic booms.

Although some research suggested ways to soften the impact of sonic booms, aeronautical technology during the 1960s and early 1970s wasn’t sophisticated enough to fully solve the problem in time to prevent the rule from being enacted.

But today, NASA is working on a solution.

“It’s a rule that many people today aren’t aware of, yet it’s at the heart of what our Quesst mission with its quiet supersonic X-59 airplane is all about,” said Peter Coen, NASA’s Quesst mission integration manager.

NASA’s X-59 is designed to fly faster than sound, but with drastically reduced noise – people below would hear sonic “thumps” rather than booms, if they hear anything at all. To test the public’s perception of this noise, part of the Quesst plan includes flying the X-59 over several communities to survey how people react.

NASA will deliver the results to U.S. and international regulators, who will consider new rules that would lift the ban that has been in place for so long. The goal is for a regulatory shift that focuses on the sound an aircraft creates, instead of a speed limit.

“We’re definitely ready to write a new chapter in the history of supersonic flight, making air travel over land twice as fast, but in a way that is safe, sustainable, and so much quieter than before,” Coen said.

Boom Boom

The origins of the federal ban on supersonic flight go back to 1947, the first time the rocket-powered XS-1 airplane broke the sound barrier and initiated the heroic era of faster-than-sound research.

At first, it was all about learning to fly X-planes faster and higher. No one gave the sonic booms a second thought, mostly because few people lived where the research was taking place.

Despite early interest in what was then a mysterious phenomenon created as an airplane flies faster than the speed of sound and generate atmospheric shock waves we hear as sonic booms, there were few tools and only limited data available to help understand what was happening.

But as the Air Force and Navy began to deploy large numbers of supersonic jets at bases around the nation, interest in sonic booms quickly grew as more of the public became exposed to the often-alarming noise.

Beginning in 1956 and continuing well into the 1960s, the Air Force, Navy, NASA, and the Federal Aviation Administration (FAA) employed resources to study how sonic booms formed under various conditions, what their effects might be on buildings, and how the public would react in different locations.

Through those years, using many types of supersonic jets, residents of Atlanta, Chicago, Dallas, Denver, Los Angeles, and Minneapolis, among others, all were exposed to sonic booms from military fighter jets and bombers flying overhead at high altitude.

Two concentrated studies – one over St. Louis in 1961 and the other over Oklahoma City in 1964 (dubbed Bongo and Bongo II, respectively) – left no doubt the public was not fully supportive of routine sonic booms coming down from above.

The tests generated national news and fueled strongly negative sentiment about supersonic flight.

The Supersonic Transport

As this work to better understand and predict sonic boom formation continued and gave rise to the first notions of how to minimize a sonic boom by changing an airplane’s shape, the U.S. government began to work with industry in an attempt to develop the Supersonic Transport, or SST.

The announcement of the SST by President John F. Kennedy in June 1963 raised interest in studying and mitigating sonic booms from a technical standpoint, turning the research into a top priority.

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The SST project aimed to produce the prototype for a new commercial supersonic airliner, capable of carrying as many as 300 passengers anywhere in the world at speeds as great as three times the speed of sound.

(Note that the speed of sound varies depending on things like temperature and altitude. At sea level and 68 degrees Fahrenheit it is 768 mph)

The aviation community was racing to develop its understanding of supersonic shockwaves to reduce the SST’s potential sonic boom noise levels. But those researchers couldn’t outpace the speed at which environmental concerns and policy discussions were cropping up, threatening to ground the aircraft before it was even built.

Three events during the summer of 1968 demonstrated this:

• On May 31, during a ceremony at the Air Force Academy in Colorado, an F-105 Thunderchief fighter jet broke the sound barrier flying 50 feet over the school grounds. The sonic boom blew out 200 windows on the side of the iconic Air Force Chapel and injured a dozen people.

A week later, on June 8, the New York Times published an editorial using the incident in Colorado to underscore the danger sonic booms presented to the nation’s peace and well-being, claiming many are “scared to death of it.”

• This was followed on July 21 with Congress directing the FAA to develop standards for the “Control and Abatement of Aircraft Noise and Sonic Boom.”

Within a couple of years, the FAA formally proposed a rule that would restrict operation of civil aircraft at speeds greater than Mach 1. Then in May of 1971 Congress cancelled the SST program and the rule banning civil supersonic flights over land went into effect two years later.

During this same time, Great Britain and France were developing and test flying the Concorde, which went on to provide commercial supersonic air travel between 1976 and 2003. There were many reasons for its demise, including a deadly crash in 2000, but economic and environmental issues top the list. Restrictions against flying faster than sound over land due to the ban in the U.S. and elsewhere greatly limited its revenue-generating options.

Speed vs. Sound

Moving ahead, to lift the ban and enable a viable market for supersonic air travel over land, the idea is that regulators would base new rules on a different standard than before.

The speed limit created in 1973 didn’t consider the possibility that an airplane could fly supersonic yet did not create sonic booms that could affect anyone below. It was a fair assessment at the time because the technology required to make that happen didn’t exist yet.

“And now it does,” Coen said. “So, instead of a rule based solely on speed, we are proposing the rule be based on sound. If the sound of a supersonic flight isn’t loud enough to bother anyone below, there’s no reason why the airplane can’t be flying supersonic.”

During the past half-century, NASA’s aeronautical innovators methodically worked through the challenge of quieting the boom. Quesst’s X-59 is on the path to proving that technology, with community overflights and the all-important public surveys to follow soon after.

Still, public acceptance of supersonic aircraft flying overhead today goes far beyond sonic boom noise. Airport noise, emissions, and climate impact are all factors that still need to be addressed.

With its government, industry, and academic partners, NASA is working to solve those challenges as well. But none of that will matter until the first step – lifting the half-century-old ban on supersonic flight over land – is accomplished.

“We are very excited to be making this big step forward, but we recognize that more needs to be done,” Coen said.

Much of this article is based on the work of Lawrence Benson, who wrote the official NASA history book “Quieting the Boom: The Shaped Sonic Boom Demonstrator and the Quest for Quiet Supersonic Flight.”

https://www.nasa.gov/aeroresearch/nasas-quesst-reassessing-a-50-year-supersonic-speed-limit

https://www.nasa.gov/connect/ebooks/nasa-ebook-quieting-the-boom

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Around the World in 10 Days

Apr 28 2023

NASA’s football-stadium-sized scientific super pressure balloon crossed the 169.24 east longitude line at about 11:32 p.m. EDT, April 25, officially completing its first mid-latitude circumnavigation after launch April 15 (U.S. Eastern time) from Wānaka Airport, New Zealand.

NASA achieved the milestone just 10 days, 3 hours, and 50 minutes after launch. The balloon is maintaining a float altitude around 107,000 feet as it continues its globetrotting journey.

“The balloon is performing exactly the way it was engineered to do, maintaining its shape and flying at a stable altitude despite the heating and cooling of the day-night cycle,” said Debbie Fairbrother, NASA’s Scientific Balloon Program chief. “As we continue to test, validate, and qualify this technology for future flights we’re also performing some cutting-edge science.”

The balloon is flying the Super Pressure Balloon Imaging Telescope (SuperBIT) payload, which has already returned brilliant research images from this flight.

Weather permitting, the balloon can be seen from the ground, especially at sunrise and sunset, as it continues on its globetrotting journey. People can track the real-time location of NASA’s super pressure balloon at this website: https://www.csbf.nasa.gov/map/balloon10/flight728NT.htm.

Next up for NASA’s Scientific Balloon Program is another planned super pressure balloon launch from Wānaka to further test the technology while also flying the Extreme Universe Space Observatory 2 (EUSO-2) science mission. EUSO-2, from the University of Chicago, aims to build on data collected during a 2017 mission. EUSO-2 will detect ultra-high energy cosmic-ray particles from beyond our galaxy as they penetrate Earth’s atmosphere. The origins of these particles are not well known, so the data collected from EUSO-2 will help solve this science mystery. Planned launch attempts will be announced on this blog.

https://blogs.nasa.gov/superpressureballoon/2023/04/26/around-the-world-in-10-days/

https://www.nasa.gov/scientificballoons

Partners Extend International Space Station for Benefit of Humanity

April 27, 2023

The International Space Station partners have committed to extending the operations of this unique platform in low Earth orbit where, for more than 22 years, humans have lived and worked for the benefit of humanity, conducting cutting-edge science and research in microgravity. The United States, Japan, Canada, and the participating countries of ESA (European Space Agency) have confirmed they will support continued space station operations through 2030 and Russia has confirmed it will support continued station operations through 2028. NASA will continue to work with its partner agencies to ensure an uninterrupted presence in low Earth orbit, as well as a safe and orderly transition from the space station to commercial platforms in the future.

“The International Space Station is an incredible partnership with a common goal to advance science and exploration,” said Robyn Gatens, director of the International Space Station Division at NASA Headquarters in Washington. “Extending our time aboard this amazing platform allows us to reap the benefits of more than two decades of experiments and technology demonstrations, as well as continue to materialize even greater discovery to come.”

Since its launch in 1998, the International Space Station has been visited by 266 individuals from 20 countries. The space station is a unique scientific platform where crew members conduct experiments across multiple disciplines of research, including Earth and space science, biology, human physiology, physical sciences and technology demonstrations that could not be done on Earth. The crew living aboard the station are the hands of thousands of researchers on the ground conducting more than 3,300 experiments in microgravity. Now, in its third decade of operations, the station is in the decade of results when the platform can maximize its scientific return. Results are compounding, new benefits are materializing, and innovative research and technology demonstrations are building on previous work.

The space station is one of the most complex international collaborations ever attempted. It was designed to be interdependent, relies on contributions from across the partnership to function, and no partner currently has the capability to operate the space station without the other.

With a continued foothold in low Earth orbit, NASA’s Artemis missions are underway, setting up a long-term presence at the Moon for science and exploration.

https://blogs.nasa.gov/spacestation/2023/04/27/partners-extend-international-space-station-for-benefit-of-humanity/

https://www.nasa.gov/mission_pages/station/research/news/benefits-2022-book

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