The Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope, NASA’s flying observatory, has now retired after its last flight that took off from the Palmdale regional airport in California at 9:14 a.m IST on September 29, flew around the North Pacific Ocean for seven hours and 58 minutes, and landed at 5:05 p.m. IST.

SOFIA, which has been in operation since 2014, is a modified Boeing 747SP jetliner, registration N747NA, that carries a 17,000-kilogram, 2.5-meter-wide telescope donated by the German Space Agency’s Deutsches Zentrum für Luft- und Raumfahr (DLR). This telescope was used to study the infrared universe and keep track of occasions like the formation of new stars and solar systems.

The development of the SOFIA mission started in 1996. Although its first flight occurred in 2010, it didn’t reach full operational capability until 2014. After completing its five-year primary mission between 2014 and 2019, SOFIA received a three-year extension. It conducted observations of the Moon, planets, stars, and more during this time, helping to pave the way for the 2020 lunar water discovery.

READ | Airborne Observatory

For many years, SOFIA has been a unique aircraft that has traveled the globe while gathering data for research into the universe. The NASA Armstrong Flight Research Center in Palmdale, California, has been responsible for the aircraft’s maintenance and operation. Sadly, NASA unveiled the end of SOFIA earlier this year after finding that the mission’s scientific productivity did not outweigh its operating expenses, according to a report.

SOFIA’s main discoveries

SOFIA made some exciting discoveries during its lifetime, including the discovery of water on the Moon’s sunlit surface in 2020. Water molecules (H2O) were detected by the observatory in Clavius Crater, one of the largest craters visible from Earth, located in the Moon’s southern hemisphere. This modified Boeing 747SP jetliner flies into the stratosphere at 38,000-45,000 feet and lands after each flight so that its instruments can be exchanged, serviced, or upgraded to harness new technologies.

READ | The 747 that carried America’s space dreams

SOFIA’s before retiring

SOFIA had an intriguing 2022. According to FlightRadar24.com, the 44-year-old aircraft flew 143 times. NASA used the ‘Queen of the Skies’ on flights primarily from Palmdale, but also from Santiago, Chile (SCL) and Christchurch, New Zealand (CHC). It was SOFIA’s first and only mission in South America when it visited Santiago de Chile. The telescope was deployed in Chile for two weeks to observe celestial objects visible only from Southern Hemisphere latitudes.

SOFIA flew to New Zealand in June. The 747 was supposed to stay for more than a month, flying several science missions. The 747SP, on the other hand, was damaged by a storm on July 18. High winds caused the stairs outside the aircraft to shift during the storm, causing damage to the plane’s front.

Following this incident, SOFIA returned to Palmdale and continued to operate several flights in California. NASA has expressed gratitude to the hundreds of people in the United States and Germany who have contributed to the SOFIA mission over its lifetime.

Pleasingly, NASA said in a statement earlier this year when it announced the end of the mission, that SOFIA’s data will be available for use by astronomers worldwide in NASA’s public archives.

SpaceX is now quite used to landing their rebuilt rockets with ease. The 23^rd of July 2022, marked their 56^th first stage landing of the Falcon 9 successfully. Gone are the days of building new boosters for each new mission and here are the days when it just takes days for SpaceX to refurbish and reuse their rockets. Quite a remarkable achievement, isn’t it? All of this may seem easy on paper but is it really in reality? Let’s get one thing straight. It is not easy to have something land on its own using computer systems onboard. The landings of the Falcon 9 look jaw-dropping and staggering from earth but what goes behind it? Let’s find out.

It is incredibly difficult to launch a Falcon 9 rocket into space and then return the first stage booster to Earth in a vertical landing, despite the company’s 80 percent success rate for rocket landings. The end of a fourteen-story aluminum-lithium alloy tube that is exploding with fire doesn’t merely find a comfortable landing in a massive empty field. The first stage’s most noticeable features are its cold gas maneuvering thrusters and aluminum or titanium grid fins, both of which are intended to give the first stage some degree of control and agility during its journey both inside and outside of Earth’s atmosphere. A lot of science behind each step.

Onboard Computers

High-accuracy GPS, gyroscopes, and accelerometers are integrated into the booster and are located at both the top and bottom end to accurately determine orientation, location, and velocity. Additionally, the booster has a large number of strain gauges that track forces acting on the structure at important points, including engine thrust. The onboard computer uses this information about the rocket’s orientation, location, velocity, acceleration, and altitude to perform the appropriate flying changes so that the rocket can make a clean vertical landing during re-entry. On GPUs, the computers process several physics equations that are then utilized to compute errors, regulate thrust vectoring, grid fin locations, and cold gas thruster (Nitrogen gas thrusters) durations, as well as optimize the flight path.

Boost-Back Burn

The booster is initially turned end-for-end while performing a boost-back burn. For a landing on a drone ship or near the launch point, the burn changes horizontal velocity. The reentry burn serves as a second chance to fix any reentry path errors while also reducing air velocity to prevent the rocket from being damaged by reentry heat. Hydraulic actuators are used to gimbal the Merlin engines of the Falcon 9’s first stage booster, allowing the rocket to change the direction of its thrust.

Grid Fins

Waffle-shaped grid fins extend that move the center of pressure of the booster upwards, increasing aerodynamic stability. The grid fins are arranged in the shape of an X-wing, stowed during ascent, and then deployed during reentry. The fins, which have a footprint of just 4 by 5 feet, are nonetheless able to roll, pitch, and yaw the 14-story stage up to 20 degrees to aim for a precise landing.

Landing

In between the re-entry and the landing burn, the booster spends a lot of time falling through the thick atmosphere. During these two stages, the booster’s slowdown from hypersonic speeds to transonic speeds all within a few seconds. The Falcon 9 actively modifies its orientation both inside and outside of the Earth’s atmosphere via thrust vectoring. The landing burn is sequenced with one, three, and one engine(s) running to reduce fuel usage. The Merlin engines are re-ignited when the booster is about to land. Upon re-ignition, landing lights and deployable landings legs are deployed that are a sequenced rehearsal for all booster landings.

Deployable Legs

A four-legged deployable landing gear comprised of durable, lightweight carbon fiber and aluminum are fitted on the Falcon 9. Just before touchdown, high-pressure helium is used to deploy the legs. To soften the landing, each leg is equipped with a shock-absorbing system.

Drone Ship

Launch sites for the Falcon 9 are located close to the ocean. Therefore, the first stage booster is bound towards the ocean when it returns to Earth following separation. These football-field-sized drone ships allow the Falcon 9 to land on the water, especially when a Falcon flight is headed for geostationary orbit. ‘Just Read the Instructions’ and ‘Of Course, I Still Love You’ are two drone ships that SpaceX currently uses during launches from Cape Canaveral.

Sources

https://www.asminternational.org/web/hts/videos/-/journal_content/56/10192/36857184/VIDEO

https://www.inverse.com/article/33904-how-spacex-lands-a-falcon-9-rocket-in-6-steps

https://medium.com/predict/how-spacexs-rocket-boosters-land-on-earth-c46694a6ef99

Cover: https://www.overtdefense.com/wp-content/uploads/2020/11/spacexrocketreturn.jpg

Rockets are arguably the greatest engineering feat accomplished by man. The capabilities of these machines are unmatched and nothing like any other machine. Such a machine is the Saturn V (5), the most powerful rocket ever flown. The Saturn V rocket is the most complicated piece of engineering ever created. It was used by NASA to send people to space between 1967 and 1973. The Saturn V was launched 13 times from Kennedy Space Center with no loss of crew or payload. As of 2021, the Saturn V remains the tallest, heaviest, and most powerful rocket ever brought to operational status, and holds records for the heaviest payload launched and largest payload capacity to low Earth orbit of 310,000 lb. (140,000 kg), which included the third stage and unburned propellant needed to send the Apollo command and service module and Lunar Module to the Moon.

Size

It stood about the height of a 36-story tall building; 60 feet taller than the Statue of Liberty. To be exact, the Saturn 5 was 363 feet tall. Fully fueled for liftoff, the Saturn V weighed 2.8 million kilograms (6.2 million pounds), the weight of about 400 elephants. The rocket generated 34.5 million newtons (7.6 million pounds) of thrust at launch, creating more power than 85 Hoover Dams. A car that gets 48 kilometers (30 miles) to the gallon could drive around the world around 800 times with the amount of fuel the Saturn V used for a lunar landing mission. It could launch about 118,000 kilograms (130 tons) into Earth orbit. That’s about as much weight as 10 school buses. The Saturn V could launch about 43,500 kilograms (50 tons) to the moon. That’s about the same as four school buses.

Missions

The first Saturn V was launched in 1967 with Apollo 4. Apollo 6 followed in 1968. Both of these rockets were launched without crews. These launches tested the Saturn V rocket. The first Saturn V launched with a crew was Apollo 8. On this mission, astronauts orbited the moon but did not land. On Apollo 9, the crew tested the Apollo Lunar Module (LM) by flying it in Earth orbit without landing. On Apollo 10, the Saturn V launched the LM to the moon. The crew tested the LM in space but did not land it on the moon. In 1969, Apollo 11 was the first mission to land astronauts on the moon. Saturn V rockets also made it possible for astronauts to land on the moon on Apollo 12, 14, 15, 16, and 17. On Apollo 13, the Saturn V lifted the crew into space, but a problem prevented them from being able to land on the moon. That problem was not with the Saturn V, but with the Apollo spacecraft. The last Saturn V was launched in 1973, without a crew. It was used to launch the Skylab space station into Earth orbit.

Speed

Yes, this 2.8-million-kilogram rocket could outfly a rifle bullet at full speed and would travel at 7 times the speed of sound. It used the powerful F-1 and J-2 rocket engines for propulsion, which shattered the windows of nearby houses when they were tested at Stennis Space Center. The first stage of the flight burned for about 2 minutes and 41 seconds, lifting the rocket to an altitude of 42 miles (68 km) and a speed of 6,164 miles per hour (2,756 m/s) and burning 4,700,000 pounds (2,100,000 kg) of propellant. And produced over 7,500,000 pounds of thrust, which is equivalent to the power of 30 Boeing 747 jumbo jets! And at this very stage, the rocket used about 20 tons of fuel per second. Yes, per second. With all this power, the Saturn V would reach excess speeds of 25,000 mph that is 15 times faster than a rifle bullet.

Stages

The stages are extremely crucial for any spacecraft and the Saturn V’s stages weren’t different either. The Saturn V consisted of three stages — the S-IC first stage, S-II second stage, and the S-IVB third stage. All three stages used liquid oxygen (LOX) as the oxidizer. Each stage would burn its engines until it was out of fuel and would then separate from the rocket. The engines on the next stage would fire, and the rocket would continue into space. The first stage had the most powerful engines since it had the challenging task of lifting the fully fueled rocket off the ground. The first stage lifted the rocket to an altitude of about 68 kilometers (42 miles). The second stage carried it from there almost into orbit. The third stage placed the Apollo spacecraft into Earth orbit and pushed it toward the moon. The first two stages fell into the ocean after separation. The third stage either stayed in space or hit the moon.

Cost

From 1964 until 1973, $6.417 billion (equivalent to $35 billion in 2019) in total was appropriated for the Research and Development and flights of the Saturn V, with the maximum being in 1966 with $1.2 billion (equivalent to $7.37 billion in 2019). Meanwhile, the upper estimate for Falcon heavy is US$90 million.

Facts

1. The Saturn V remains the only spacecraft capable of taking human beings to another celestial body.
2. It also remains the largest and most powerful rocket ever built with a load capacity (to low earth orbit) of 260,000 pounds.
3. It went from paper design to flight in 6 years (1961-1967).
4. The Saturn V liftoff was so loud that you could see the sound waves.
5. It could fly 7 times the speed of sound.

A Living Legend

We might never be able to make something as magnificent and raw as the Saturn V. This did set a benchmark for how powerful rockets should be and is still unrivaled to this day. It opened a new gate to explore deep into space and put into action what humans can achieve if they work together. The Saturn V is currently on display at the NASA Johnson Space Center.

Sources

• https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-was-the-saturn-v-58.html
• https://www.thrillist.com/culture/things-you-didn-t-know-about-the-saturn-v-moon-rocket
• https://en.wikipedia.org/wiki/Saturn_V
• History of NASA (Cover photo)