The Incredible Transformation of a Boeing 747SP into a Space Observatory - SOFIA! 

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Thank you @Mentor Pilot for coving this because my dad had a hand on making this happen and he helped with installing the door of the telescope and I AM GLAD that it is going to a museum in California do that I can actually see what my dad actually worked on ;)

Cool to see how the telescope is stabilized at 9:59. Keep in mind: The telescope stands perfectly stil. It's the airplane around that is shaking in flight.

I'm an astronomer, sometimes glider pilot, and an appreciator of aviation engineering. What more can I say, other than that was very enjoyable watching. Ta! 😁😁😁

I actually live in Palmdale (where the SOFIA is based) - my house is actually just off the extended centerline of runway 7/25, so several planes that take off and land from there pass almost directly overhead at low altitude. Because of this, I've actually had the privilege of seeing SOFIA a couple times as it approached for landing.

SOFIA has flown at least two or three times in October, although not on NASA missions. Edwards AFB hosted an airshow on the 15th and 16th and they managed to get SOFIA there, where I was able to get a few pictures. There was also an overnight trip to the Bay Area the night before. There may be a couple more, but I’m not aware of them.

Imagine if humanity put all the money and effort it spends in bickering and in wars into science and technology instead. Projects like these, even if they do come to an end, inspire hope and awe.

Thank you for the detailed design information on the special version of the 747SP, and regarding the presentation and announcement of the SOFIA project. The aircraft was in Stuttgart for a few days in September 2019, and I had the opportunity and luck to visit it directly at the airport from the outside and inside. The most impressive thing for me was that this aircraft can fly with the flap open, flying so smoothly that it can take sharp long exposure pictures. I also found the plane to be quite "bare" on the inside, lacking the wall panels you see on passenger planes, you could directly see the struts of the plane's body. That's why it was relatively cold for the scientists who flew along and sat at their monitors etc. in the fuselage, they had to dress warmly. It was also interesting to learn that the airplane does not reach the maximum flight altitude at the beginning. This is because in the beginning it is too heavy to reach the maximum flight altitude due to the fuel it has been refueled with, and it starts at about FL 390. Only after several hours, when enough fuel has been burned in the course of the flight and the aircraft has become lighter as a result, does it climb in succession to the next higher flight level, up to FL 450. Since it mostly returns to the starting airport, but on the other hand the telescope must always be able to observe the same part of the sky for a while, it flies "almost" straight ahead for a while at a time, and then changes direction and flies straight ahead again for a while, with the route leading back to the starting airport at the end. The "straight out" flight paths are not completely straight, however, but somewhat curved, since the telescope must maintain its line of sight relative to space as the Earth rotates away beneath it. This is how the typical flight paths of the SOFIA aircraft are created, as they can also be seen clearly on the following page. www.dsi.uni-stuttgart.de/institut/aktuelles/news/Fliegende-Sternwarte-SOFIA-zu-Gast-am-Stuttgarter-Flughafen/

The launch of the JWST was so precise that the time of service was extended to 20 years. SOFIA deserves all the kudos for bringing us to JWST.

My wife and I used to live off the west end of PMD and SOFIA would take off over our neighborhood. It was an amazing airplane to see down low. Unfortunately we had already left California before she did her last flyby on the way to the museum in AZ. On a side note we named our dog NASA because SOFIA flew over the house the night we got him! Thank you Petter for the great video. It got home for us.

This is such perfect timing. I’ve only just found (and am now completely hooked on) this channel. My dad was a pilot for 20+ years (now retired) and spent a good amount of that time flying the Boeing 747-200- and was based in Sweden at the time. Very much looking forward to sharing this series with him ✈️

The most interesting things I learned here were 1) shorter planes need longer tailfins (seems obvious now you point it out, but i'd never noticed) and 2) The overlapping wing box enabled the creation of the 747-400. As they say, you learn something new every day.

I'm over 30 years old, and "it discovered the rings around Uranus" still makes me chuckle.

I'm an astrophysicist turned atmospheric scientist, and I was really sad when SOFIA was decommissioned. A friend of mine worked with it during his postdoc and he seemed to really enjoy it. I'm totally jealous of him lol. There is a lot of atmospheric measurements made from aircraft, and they're super useful for science, satellite data validation, and weather forecasting. I don't know how they're acquired though (I'm definitely on the receiving end). Would love to see you explain it all :) Thanks for the awesome content, as usual! :)

I must still be 13, because "discovered the rings around Uranus" still makes me giggle uncontrollably.

At Lufthansa Werft in Hamburg (SOFIA was actually there for service when i visited) they told us, that NASA had problems to certify the aircraft after the modifications and finally decided to declare is as a spacecraft to avoid the hassles.

I've worked at Boeing 8 years- I'm a nerd for this kind of special aircraft, but I never knew this existed until today. What awesome engineering. Whenever this makes it to a museum I'm definitely taking a trip to see it in person.

Thanks for doing this topic! I’m an astrophysicist who loves commercial aviation, so this video was a treat from you, Mentour!

I just walked through the SOFIA observatory a couple of weeks ago. She was visiting Moffett Field in California and they had an open day before her retirement. It was super cool.

A passenger window of that size would really be cool 😎

I did see it during it's D-check at Lufthansa Technik Hamburg in 2014 as I worked there in the VIP department. It was launched 2007 not 2014. One day we heard about SOFIA being there and getting checked, as no other company in the world was willing to do this maintenance on this special aircraft. So we went there after lunch break and took a good look. Then one of the scientists catched us looking and gave us a tour and some infos on a model and some demonstrators for the telescope mounts including the vibration control air buffers. Great day that was. We almost missed the end of our shift. What a piece of tech it is. The rear section did not just get another pressure bulkhead. The whole upper section was replaced with a bigger section to fit the door and opening into it. They also added a whindshield just before the door opening to shield the telescope from the wind and counteract the aerodynamic effects of the open door during flight. The 747SP has also the advantage that it can fly very high as it has the wing of a bigger airplane and significant less weight on it.

So excited you're doing this subject! Sofia is an amazing observatory, sad to see it go!

Imagine how awesome it would be to do astronomy at FL450!

I live and work right by where SOFIA is based, and I've watched her take to the skies many times, both with my eyes and on a radar scope. Got to see her up close and personal just after her final mission, since she was open to public tours at the Edwards Air Show a few weeks ago. What a cool piece of history and science.

As a sky watcher and amateur astronomer, I absolutely loved this. For those who want to know a little more about what it was like during an observing flight on SOFIA, Emily Levesque has a chapter that describes a night on board in her book "The Last Skywatchers."

09:14 - Not to forget that even Concorde was used for astronomical observation. The prototype 001 had its roof cut and windows installed for observing the eclipse overhead, which permitted 74 minutes of continuous observation of the eclipse, as compared to the 7 minutes that would otherwise be possible for ground-based observers.

We used to live practically under the flight-path (north end) of Sea-Tac Airport. My dad was a Boeing engineer (yeah, I'm a Boeing brat). We were walking home from the bus one day and I yelled, "Look at that little bitty 747!" and he chuckled and told me it was an SP. Love this video, and I'm glad RU-vid recommended your channel!

I am not a pilot (just an Engineer who has always been interested in aviation) but I find all of your videos informative, professionally done and fascinating please keep up the great work!

A few years ago a friend spent a night onboard SOFIA as a member of the science team when she was working out of NZ. (I think "working" is a loose term during the flight a much of the work is actually done before and after the flight if all goes well.)

This is absolutely wonderful. Beautiful coverage of some thing different in aviation. Thank you.

I live in Christchurch, New Zealand where SOFIA was stationed for 4 to 6 months out of every year, for the Southern Hemisphere season. The Nasa guys were just lovely to deal with and they seemed to really look forward to being stationed here. It was always really nice to see her parked up on the Antarctic Apron (where the C-130s bound for Antarctica also parked) at Christchurch Airport. I went inside Sofia and got the grand tour from the guys. What an Amazing craft she was both inside and out. All of the technicians were seated and surrounded by screens. It reminded me very much of the flight deck of the 'Nostromo' in the orginal 'ALIEN' movie. Surrounded by beeping, whirring and a hussle of activity. Technology all around you, like being encased inside a giant computer. The huge articulated telescope was in the same compartment right next to us and trust me it was an impressive sight. I'm genuinely sad ill never get to see or go on board SOFIA again.

Great video and very informative, It is a shame you couldn't have Kelsey' input on this one. Keep up the good work, thank you for the content, and I hope you are enjoying your time.

One thing that is interesting to me is that it was determined that for the infrared telescope, putting a big window in the aircraft instead of a door was apparently not optimal. Obviously it's a much better aerodynamic solution but I am guessing it isn't transparent enough from the point of view of the infrared telescope.

I was the lead instrumentation engineer on SOFIA at L-3 Communications (formerly Raytheon) up until delivery of the aircraft to NASA. I had the privilege of working with the amazing engineers, electricians and mechanics that designed, modified and built this fantastic aircraft. I got to witness the entire modification process and was actively involved in the ground and flight testing up to delivery. It’s truly an amazing aircraft but as they say, all good things must come to an end.

It's amazing how many design changes were made for this variant.

i cant resist pointing at it, 9:32 quietly lmao

I saw SOFIA in 2019 when she was stationed in Stuttgart back then. She was a real beauty, this incredible plane with TWO humps. SOFIA is one of the best examples of two engineering powerhouses cooperating: NASA: "We want a new flying telescope. A BIG one." DRL: "Say no more, we got you covered." NASA: "Great! Let´s do it together! You bring the telescope, we´ll get a plane for it." DLR/NASA: *high five* I will really miss her, now that she is retired.

Thank you for this episode Petter! That was a gem! As an aviation but also an astronomy enthusiast I really enjoyed it!

I called the SOFIA office. I wondered why the 747SP had not upgraded to the 747-8 wings and engines. In other words get the smallest 747 and put the elevator for the largest version of the 747 lifting it. This would increase range and altitude substantially. To my surprise they answered "We wanted that but the reply was to do this as cheaply as possible". SOFIA is a great piece of kit! I can only hope SOFIA-B might one day fly even higher and on longer observing sessions with these upgrades.

Just last year I met a former NASA scientist, now living back here in Australia, who was heavily involved in building the telescope for that project. It was fascinating to learn a few details about it, and the challenges to work together using multi-national teams. If I remember correctly, she did notice a distinct difference in approaching issues between her American and German colleagues.

Great addition to your videos, Mentour - hope you have much joy and success till you are back in “your” Boeing cockpit again in spring! Cheers and all the best for you from Germany, Pepe

Thanks for the SOFIA story. I was working at NASA on the 12 Foot Pressurized Wind Tunnel Restoration project as tech rep for the tunnel operators - The Unitary Plan Wind Tunnel division. 1996 was the end of the project and the engineering team was assigned to the SOFIA project. It also was almost the end of my days at NASA. I was also ready for retirement. Fond memories of my days at Ames.

I love the way you set this up. The history, tied to the why, tied to the mission. Really nice job.

Well not a science channel you have presented a very scientifically literate and accurate description of this remarkable instrument. This has been a better video than presented on some of the exclusively science channels I subscribe to. Congratulations it's not easy being both technically accurate and scientifically complete.

Sp long, SOFIA. You did a wonderful job!

i remember when they flew these things in the jet stream on express runs between tokyo and honolulu. we used to watch them nearly dive bomb the runway for landing because they took pride in trying to stay in the jet stream as long as possible. good times.

Thanks captain, I flew on EP-IAB Tehran-Seoul back in the early 2000s, glad to have flown on this special bird!

I know a guy from San Francisco that worked on SOFIA. When asked how they aimed a telescope in a 747 he answered "VERY CAREFULLY" lol. Not sure if she still does it but at the time his wife was doing work for the Mars Rover. Really nice and humble couple and obviously incredibly smart. I've known them for years through the competitive sound quality niche of the car audio community and it's a VERY tight (and small) community where everyone seems to know everyone.

That's just fascinating! When I'm clipping along the highway in my car and lower a rear window, the buffeting air is obvious- and that's only at 120 km/h. Imagine the effects with 747 air speeds! Sure, there's a pressure bulkhead separating the telescope area from the rest of the fuselage, and sure, the air is much thinner upwards of 45,000 feet- but it's still staggering to me that it is reported to have flown like this giant door wasn't even open. I'm also impressed that the buffeting that I picture in my mind, was able to be counteracted by the design of the telescope. Thank you for this very informative video, I enjoyed it immensely!

Thanks for another great video! I especially liked this one because it combined two of my favorite things...the 747 AND astronomy. No surprise NASA picked the Queen for this project and that it was such a success. Very sad to see it come to an end and I'm with you Petter, I'd much rather see SOFIA repurposed in another project than just sitting in a museum. Interesting too to learn about this version of the 747 and how she was modified for the project. It will be a very sad day indeed when production of 747's comes to an end. Thanks again as always for another very interesting and informative video! Well done!

09:30 Oh no my secret is out!

I lost it at "the rings around Uranus", at the age of 30. I will probably never grow up… 😂

From what I know, JWST cannot replace SOFIA. SOFIA operates in the far infrared range from 0.3 µm to 1600 µm while JWST operates in the near (0.6 to 5 µm) and mid infrared (5 to 28.3 µm) range. But for a long time there had been discussion about their operational cost. I find it very sad, since it really leaves a gap.

Wow what an interesting and fascinating video Petter! I can totally see and understand why the hard questions were asked and the decision was made to retire SOFIA after the successful launch and service performance of the James Webb IR telescope. Thanks for a great video on this fascinating topic. Nicely Done!

Very nice love letter to SOFIA. It was my favorite telescope. What could be better, astronomy married to coolest of the Queen of the Skies. Thank you for this video!

Sophia flew over to the Edward's airbase for the airshow. It was beautiful to see her in the sky one last time!

Sad to see SOFIA go away. It demonstrated fantastic engineering and design efforts from a group of Aeronautical Engineers and Telescope scientist. It also shows how fast we are moving through technology. It is possible that the Webb Telescope is already obsolete, and we should expect something new in the next 2 years or so.

Great video, i had no idea that SOFIA only lasted 12 years, it felt like much longer, but i guess i might've been thinking of KAO. But cool to see that you're doing deep dives into historic airplanes, because even though there are many channels around that do this, but there aren't many pilots doing it, which makes these feel more 'official'. Even if you all use the same wiki data, a professional will add more details from their own knowledge, good stuff!

When Mentour Pilot Aviation and Astronomy comes together ❤❤❤❤❤ Me fanboying like crazy!!!! This was so awesome! Me imagining a collab between Petter and Anton Petrov (Hello wonderful person) 😍😍😍😍

Delicious topic, Petter, thank you! I've always had a passion for astronomy. Hope you're feeling absolutely fantastic. :)

Combination of two of my favorite subjects! Aviation and astronomy ❤️❤️

Used to see this flying in my home city of Christchurch during winters. Was really cool to see it flying. I also was lucky enough when young to get a personal guided tour of the Kuiper Airborne Observatory when it was in own once. Was really cool to see all the tech inside. Not much room in there

DLR = Deutsches Zentrum für Luft- und Raumfahrt (lit. "German Center for Air- and Space-flight", German Aerospace Center) is the national center for aerospace, energy, and transportation research of Germany and acts as the German space agency responsible for planning and implementing the German space program on behalf of the German federal government

Thank you so much for creating this video and while I was aware of the background of Sofi I have been wondering about the project and the overlap with the James Webb project. I am sad to hear of the end of the program and the 747SP will always hold a special place n my heart as well.

Currently in school for my A&P license and a huge space nerd, was so sad when they announced she was retiring. Would have been a dream job being an AMT with the SOFIA team!!

What a fascinating and insightful video and most importantly, so easy to understand. Thanks again, Peter.

Thank you for sharing this presentation and for the amazing explanation about this amazing aircraft and its research.

I saw one of SOPHIA's last public displays @ Edwards AFB last month. Low & slow flyby with the telescope door open. Cool to see.

I think it would be fascinating to be a part of the team doing the design and build of something so incredible. 👌

Many years ago, pre-9/11, I checked out of my Boston hotel early and went to Logan to check in early with United and see if I could get an earlier flight to LAX. The agent told me there was an unscheduled flight to LAX leaving in a bit. It turned out to be an SP doing a relocation flight. I don't know what it was doing in Boston, and I think it was only one of 2 that United had at the time. In any case, it was a phenomenal bit of luck to get to ride on one.

Wonderfully presented and very informative. Look forward to seeing more of your videos.

Thank you for this, was lucky enough to have a tour around this when it was working out of Christchurch airport a few years ago. I don't suppose we will ever see a 747SP out this way again.

Sophia was here doing touch and goes yesterday, she has been here every month or so doing touch and goes for a few years. Fresno Ca I always get great pics as it flies by my backyard

Sad to see SOFIA retired, I've always thought it was one of the coolest telescopes out there.

Man I’ve never heard of that before that’s super interesting.

I have loved the 747 since I was a kid. My cousin had some really nice solid metal commercial designed aircraft toys. We used to quiz each other to identify them by engine placement, rear stabilizer design and so forth. His room was also on the top floor of the house which was on a hill and we could see the airport. He had a radio receiver that we could listen in to the communications as we observed the planes coming and going. The 747 has been a favorite since those days and fond memories. Sad to see it coming to an end, but life goes on.

I spotted SOFIA flying overhead once. As an infrared astronomer, I have always wanted to use it. The biggest problem with SOFIA is the sensitivity. It can reach far into the infrared, but the sensitivity is quite poor. As a result, there are not too many things bright enough that you can observe with it. Is it completely obsolete? Absolutely not. JWST goes out to 25 micron; SOFIA reaches 600 micron. It also has many instruments that JWST doesn't have, and can be upgraded as mentioned in the video. But sadly, with the finite research budget we had to work with, SOFIA had to be let go.

In 1988, while living in Johannesburg South Africa, a South African Airways 747SP regularly flew over my home as it approached the airport.

My dad flew the 74-sp for PAA. They had it on the NY to Tokyo. At the time was the only plane that could do it non stop. Great vid. Cheers

Just popping in to say this was one of my favorite videos in a while.

Never knew it existed so thank you so much for covering the retirement of this very unique aircraft

I had a family member who worked on SOFIA. They told me this really cool story about how being able to take an observation from a specific location is super useful. So not too long ago, Pluto was going to pass in front of a star and cast a shadow onto the earth. This eclipse shadow was only going to be (i think) 10s of miles wide and moving across the Indian ocean at roughly twice SOFIA's cruising speed. No other telescope could have taken this observation. They set their course so the eclipse shadow was going to overtake them, passing right over them. My family member told me about how the light data showed this textbook-perfect lighting curve, dimming down with a little spike in the middle as the eclipse shadow moved over them. So frickin' cool! I'll miss SOFIA, but I definitely agree that the $1 000 000 per flight hour is a steep price to pay, even for the unique data it gathered.

“Uranus” was funny :)

I had the great opportunity to see the sofia 747 in Christchurch New Zealand a few months back. pure coincidence that I was heading to christchurch from Australia the day before it was due to leave for the last time. it was an absolute joy to see it parked on the Antarctic apron and awesome to see engineering excellence.

Great informative video. Thank you

That was absolutely fabulous!

I love your non-passenger airplane streams. It's uber exciting...

SOFIA is being flown Tuesday 13 December 2022 to Davis-Monthan AFB, Tucson. In January she will be moved over to PIMA Air & Space Museum.

I'm sad for SOFIA as well, but the writing was on the walls. I just wish science fever would grip society like it once did. Science is on the chopping block!

Thank you for this episode and your detailed explanations of the subject. I enjoyed it very much because I helped to produce the bearing of the telescope which is able to stabilize it during flight to the highest precision ever archieved. 22 years ago the Bearing Company FAG was with its equipment in their plant in Wuppertal in Germany the only production in the world which was able to do the finish operations at the bearing in the requested precision. At that time it was the most precise hydrostatic bearing ever made with oil gap totolerances of +/- 10ym on a sphere of 1.2 m in diameter. This super high precision was necessary to avoid any stip-slick-effects for the actuators to compensate the movement of the airplane in flight. We had been working together with the MT Aerospace AG in Augsburg (at that time MAN Technologie AG) for the DLR to complete the telescope. The assembly of the telescope into the airplane was delayed for many years because President Bush stopped the NASA project SOFIA for financial reasons until President Obama reactivated SOFIA and the telescope was finally mounted into the plane 13 years after its production in Germany had been completed. It's a pity that the time of this flying telescope seems to be over. As far as I know it was scientifically a very futile cooperation between the scientists from Germany (University of Stuttgart) and the US astronomers during these 8 years of operation.

great video, reminds me of older mentour channel videos

Great observations Captain.

I was a 6year old child when 747 took it's first flight. When the Pope visited Ireland in 1979, he arrived on an Aer Lingus 747 which was escorted by two Irish Air Corps Fouga Magisters in tight formation. It made for an amazing historical photograph.

Brilliant video! I love the 747 but I think this baby one is the cutest! This video was so interesting from both an aviation and science perspective. thank you 😊

Great video Bro 👍

Just wanted to say the 747 is still the most beautiful jetliner. I've had the pleasure of riding on a few and it's super comfortable, and you can feel the immense power at takeoff thrust. I will always love that design.

This is awesome!

I hope this amazing plane and its technology is preserved in a museum.

Just watched this video and the one about the last 747 built. Excellent content as always. If I may, you should continue doing once in a while more historic and unique aircraft content, for example the 747s modified as space shuttle carriers, the 747 Galactic Girl from Virgin Orbit, Samaritan’s Purse DC-8, the aircrafts flown by Orbis the Flying Eye Hospital, etc.

Always nice to see international cooperation. A work together of the National Aeronautics and Space Administration and the German Aeronautics and spaceflight Institute