Tag Archives: astronomy

“Contents may shift during your flight.” Well, I may have, but not this 2.5 meter diameter telescope aboard SOFIA.

Reposted from https://blogs.nasa.gov/mission-ames/2013/06/12/post_1371070856575/.

After boarding, we had some time before the doors closed. A safety briefing was held. Upon entry to SOFIA, one objective, as this was a relatively “full flight” with 30 people, was to stake out a seat for take off(a comment was even made of the ‘Southwest Airlines’ way). Seats are scattered about the airplane for specific purposes and prior to this flight, my colleagues and I had worked out our seating. We could only send one representative to the “conference table” seating area, so Martin Garay (a student at Ithaca College) and I were sent to business class, while Luke Keller (our grism lead, astronomy professor at Ithaca College) sat at the “conference table” midway along the telescope deck.

Sketch of the seating on the telescope deck on SOFIA. There are additional seats on the upper deck.

During the prep for takeoff, I took the moment to inspect the on-board safety information card. It re-iterated what we learned in egress training and what was described as we boarded. Indeed the inside of this 747SP is very different from your normal airline experience and being aware of your surroundings wherever you are is important.


Compilation of photos of the SOFIA on-board safety information card.

The engines started at 715pm PDT (local time), and we took off around 7:27pm PDT. It was a good 50 seconds for takeoff. And essentially, it felt like a normal jet takeoff sitting up in the business class section.However, unlike a normal airline ride, within a few minutes we were allowed to get out of our seats. It was just so surreal to be walking down/up the plane during the descent. It sort of felt wrong, as we are accustomed to the strict rules on commercial aircraft, but it was so important to use any leg designed to bring the aircraft to the 40,000 ft science altitude, to do non-science things like setting up computers and testing connections between the systems. On this flight, every second counts! And that theme was certainly reiterated throughout the night.

By 8pm PDT we were at 35,000 ft. The pilots had already completed 3 legs of a 13-leg flight plan.

And at 825pm PDT, the telescope door opened! Within minutes, Joe Adams, the FORCAST lead instrument scientist, had started his first script to check out the detector frame rate settings.

One of the first data acquisitions of SOFIA Flight #105. Target is R Leo.

We hit pockets of turbulence during ascent and near the “weather” areas we had been warned about, and although the aircraft seemed to be moving up/down/sideways, the telescope moved as well. It was mesmerizing to see the FORCAST instrument and its counter weight moving about the cabin and yet the position of the star in the telescope guide camera was “rock solid.” Indeed, contents shifting during flight, but not this telescope! Two times during the light, the turbulence got bad enough that we had to return to our seats and the telescope was “secured,” but both episodes lasted less than 10minutes.

From Jim Debuzier’s (the lead instrument scientist) log, hewrote: “09:45 [UTC] Turbulence like a roller coaster. Everyone’s sitting (whether they wanted to or not), and the telescope is in local. Riding it out until we can start observing again…)”

What was fascinating was that according to the mission manager, we probably lost about an hour due to turbulence. We had to sit down about 2x during the flight for a period of 10-15 minutes. I lost all track of durations of things, as I was focused on what data we lost by these unexpected interruptions. But each time we faced turbulence, we just took it in stride.Around 08:20 UTC (1:20am PDT) we also needed to do small flight diversion from our Leg #9 to avoid some baby tornado clouds. This time the timing was good as we were doing some calibration flats which did not need a target so we could still take data during the diversion.

You can see what the actual flight path was by visiting http://flightaware.com and searching on NASA747.


Screengrab of actualSOFIA Flight#105 flightpath Jun 11-12, 2013 from Flightaware.com


Screengrab of logged SOFIA altitude and speed for Flight #105 Jun 11-12, 2013 from Flightaware.com

Kudos to the pilots for giving us a very good flight and working with the weather patterns!

One thing to mention, as we were free to move about the cabin, each of us had to carry with us a EPOS, emergency passenger oxygen system. In case there was a depressurization at 40,000ft, there would not be enough time to get to the nearest seat for oxygen masks. It was a small nuisance to carry a bag with you everywhere, but it did not get in the way of getting the work done, planning, executing, and analyzing the data on the instrument.

One of the passengers, a member of the DAOF staff, carrying his EPOS, the khaki-green pouch on a shoulder strap.


This ain’t your normal in-flight safety demonstration video. SOFIA Emergency Egress Training.

Reposted from https://blogs.nasa.gov/mission-ames/2013/06/11/post_1370924602136/.

Note: Photos taken during of a safety video during a training class, not of optimal quality, but enough to capture a pretty unique airplane and its emergency procedures.

I have returned back to Palmdale, CA, the base of operations of NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA. This week there are scheduled two flights to 40,000 feet to complete commissioning activities of the FORCAST mid-IR imager with grism complement and some firsts cience activities of the Cycle 1 period. The two flights are Tues Jun 11thand Thurs Jun 13th, sunset to sunrise.

Tuesday marks my first flight on SOFIA. Being a newbie, I am required to attend egress training. I took this class along with a student fromIthaca College who is helping with our grism data pipeline and four SOFIA AirborneAmbassadors, education specialists from El Paso, Texas. All the other flyers have had this training.

For more information about the SOFIA Airborne AmbassadorProgram, check out this link: http://www.seti.org/sofia.

The briefing started with a description of the location of the exit doors, and hatches. To note in this 747SP there are no over-the-wing exits, and no floor lighting to illuminate the path out. The two side doors act just like any other jet egress doors, each equipped with an evacuation slide.And no, we did not test the slide deployment on the plane, as that costs tens of thousands of dollars to repackage the slide and recertify it for flight.

A lot of discussion was about the location of the oxygen masks and life preservers because depending where you are sitting on the plane,or what station you are at during flight, the location varies. We were shown a multitude of oxygen masks. The figure below shows top left: standard drop-down masks that we are commonly familiar with, top right: EPOS, or emergency passenger oxygen system (also known as a smoke hood), bottom right: the masks for the pilots and the mission manager (also includes a communication system),and bottom left: portable oxygen tank which is part of some of the special seats on the telescope deck. There are masks in the toilets, and some are portable to carry with you if you are moving about the cabin. The presentation was a video plus a hands-on demonstration.



We went over locations of the fire extinguishers, first aid kits, AED (automated external defibrillator)and emergency survival kits. On each flight, there will be 6 crew members, with 4 up on the upper deck (pilot, co-pilot, flight engineer and tech) and 2 safety techs on the telescope deck. But with on order 20-30 passengers scattered between both decks it really is important to know where all this special equipment is located. Nothing is standard on this 747SP.

We looked through the emergency survival kit and handled the different radios and beacons in case we need to assist the crew. We also learned that the Mission Manager serves as the main point of contact for direction in case of an unexpected emergency.

The next step in my SOFIA adventure will be a crew briefing on flight day around 5pm, where specifics of each flight leg will be described.There will be an on-board safety summary as well. I was out here for line ops two weeks back and I have to admit I never really looked for the safety equipment, so rest assured now that I now what I need to look for, I can spot the equipment exit areas that were discussed in the briefing tonight!

I close with a still I took from the safety video showing the escape hatch from the upper deck of the 747SP. Apparently you have to grab hold of a special handle (and there only a few) and rappel down. I really hope it does not come to that, but I am glad I know about the upper hatch, escape routes down through the nose gear and side doors.


Adieu from Palmdale, CA, for now, until returning for SOFIA commissioning flights

Reposted from https://blogs.nasa.gov/mission-ames/2013/05/24/post_1369400358836/.

We completed night 2 of line ops for the mid-IR camera FORCAST on SOFIA. Our tests included script validation of the main observation modes for the imaging and spectroscopic (grism) channels, optimization of detector bias, and exploring a new way to improve the flat fields for the imaging modes. During part of the night, we were slowed down by debugging of scripts, an activity we were glad we found issues with now, rather than inflight. As a result of the delays, not all the planned tests were completed,but May 28th is the next line ops for this instrument.

We did manage to get our first grism spectral tests in, but more testing remains for May 28th where my colleagues will take over the testing. I will be on call for data analysis.

I head back to my home in Boulder, CO, today, after a powernap. I will be returning to experience a flight on SOFIA on Jun 11th.Until then another line ops is scheduled for May 28th, followed by commissioning flights on May 30, June 4, June 6, and June 11th.  I’ll be on call for data analysis and wishing my colleagues clear skies, good script runs, and completion of the readiness tests. SOFIA soon enters formal science flights at the end of June, and we want to give the larger community a high performing instrument with an observing strategy to optimize time and signal-to-noise.

SOFIA on the runway at NASA’s DOAF, Palmdale, CA during FORCAST line ops May 2013.

Who’s Sitting in the Driving Seat when you Fly the Infrared Friendly Skies?

Reposted from https://blogs.nasa.gov/mission-ames/2013/05/23/post_1369353993976/.

Note: The pictures in this blog are taken from a recent line operations (when SOFIA is not in flight, but being operated on the runway) on May 23, 2013. As the program is in its iterative operations phase, these pictures capture the inside of SOFIA on this date. There will be additional preparations to enable the required safe readiness for the flights, the first set for May 30th.

At one level SOFIA is quite simple: you want to point the telescope at for target, hold there on the instrument sensor array for a set amount of time, maybe repeat the observation to allow for better signal-to-noise, and then move on to the next target. At another level, SOFIA is quite complicated as you have a moving observatory (in several degrees of freedom, i.e., forward, left, right) that is trying to target, “peak up” and stay on target for several minutes by which the observatory and/or the target has moved enough.

Mission Director: He/she is responsible for ensuring the flight meets the success criteria and is safe. They run the readiness reviews and summary the milestones for the flight campaigns. They also make decisions if needed to deviate from plan. They keep track of how well we are executing the plan.

The Flight Planner: On the plane he/she sits next to the Mission Director. Lots of work is done ahead of the actual flights to map out an optimized series of “flight legs” to maximize the time spent on target. As the telescope has a fixed position within the aircraft (aft-port), a leg towards the West (in the Northern Hemisphere) means the sky target is in the south; a leg towards the North means the sky target is in the west, etc. When SOFIA flies in the Southern Hemisphere, this gets reversed.

More information about SOFIA Flight Legs can be found at SOFIA Flight Plans.


The Telescope Operators. Sitting close to the telescope, they monitor the telescope set-up and operations and real-time interfaces with the science instrument. Each science instrument will have different requests for the telescope assembly. They also perform the Line Of Sight rewinds periodically. Normally this is scoped out in advance but this is envisioned to be a manual operation performed with agreement the Instrument Scientist’s okay. For example, you don’t want to interrupted an observation, so you are watching the clock and the angles in real time to know when this activity is needed.

More information about SOFIA Line of Sight can be found at SOFIA Line Of Sight Rewinds.

Instrument Scientist. Each science team will have an Instrument Scientist who knows the “ins and out” of the instrument and the subtleties of changes to observations or techniques. He/she is in constant communication with the Telescope Operator as well as the Principal Investigator of the observations. Science Instrument observations are run mainly by pre-written and pre-tested scripts, but sometimes there are some manual observations that the Instrument Scientist can execute.


There is also a lead for the MCCS, the Mission Controls and Communication System, to supervise the performance of that critical subsystem. This software controls the communication between the science instrument and telescope as well as all the archiving of any data taken during the line ops or flight.

There is the Science Team who is on board for the in-real-time data reduction and assessment, in case an observation needs to be redone again or done differently,  a Principal Investigator who decides the priorities of the science observations for the flight and directs the science team and  two pilots and a flight engineer for flying the aircraft.

Finally, there is space allocated for ride-along teachers and other guests who can participate in SOFIA science.

To learn more about the SOFIA Airborne Ambassador program check out SOFIA Airborne Ambassadors Program.

‘To Chop, Nod, or not Chop, Nod. That is the question.’ SOFIA FORCAST May 23, 2013, line-ops.

Reposted from https://blogs.nasa.gov/mission-ames/2013/05/23/post_1369351626283/.

I am out here in Palmdale, CA, not for a SOFIA flight (yes I know that’s where most people’s interest peaks) but for a critical step called line-ops, or operations on the flight line. Essentially we are going through exactly what we plan to while the plane is at altitude and work on end-to-end data testing, assessing observation timing, and communication, both among the different people needed to complete the observation and also between we humans and the highly complex software subsystems.

At 2130h May 22, crew briefing. We covered the main readiness topics: Weather (winds, humidity), Required Personnel, AircraftStatus and Configuration (System Engineer reported out), Telescope Status,Mission Systems Status (Flight Systems reported out), Operational Timeline(roll out, people on, telescope door open, telescope door closed, people off,roll back to hangar), Mission Rules (don’t connect laptops to the internal system and wireless at same time, bring drinks in closed containers, get permission before entering roped off areas, etc.), Safety & Emergency Procedures (exit doorway locations, footwear required), and Test Summary.

Being on SOFIA is not like flying on a normal 747 jet. I hope from the various photos in this blog entry and others, you’ll see it’s got“other things” like computer racks, a whole data collection and archiving server farm on board (the MCCS), conference tables, and various electrical panels needing access for maintenance or operation. It’s got airline seats(with the normal seat belts) for takeoff and landing and places to store your laptop bags, but the similarities end there.

So last night we got through some key tests. We did a pupil check (to optimize alignment of the FORCAST instrument to the telescope). Next were a series of inspections of the telescope boresight (telescope centered ona star) and how that appeared on all the imaging (all filters) and spectroscopy(for all grism and slit combinations) modes. We learned we had a systematic offset in our slits, but we updated the .ini file to address this. Then we did some testing of the basic modes. We tested chop-nod-dither in the SIRF and ERF coordinates. SIRF=Science Instrument Reference Frame (rows & columns on the detector array). ERF=Equatorial Reference Frame (RA/DEC on the sky). There is also a third coordinate system, the TARF=Telescope Assembly Reference Frame (elevation,x-elevation angles). Yes, astronomers love their coordinate systems.

Below is a photo of one of the chop-nod tests, on a bright target star. It’s chop-nod-match mode. Left is the Science Instrument Console with quick look software showing a reduced subtracted image (you see the positive and negative star images). The right image shows a series of display for the telescope guide camera and telescope display.


With the remaining hours for this night, we started probing the space of the chopping throw vs. angle. Below is an example of a large chop that was bumping up against a hardstop of the secondary, so we spent the rest of the night investigating that issue. The scale bar on the lower left of that guide star camera image is 1 arc minute.

The telescope door was closed at 0500h. Sunrise was at0545h. We’ll regroup later tonight to address the series of tests for tonight. There will be a crew briefing at 2130h to assess readiness for tonight.

Oh, surprise to me, we had internet on lineops, so I was tweeting away in near-real time we did our testing and I also got some IDL coding done for the pipeline end-to-end tests.