Pluto, “King of the Kuiper Belt, Prince of the Plutinos.” Certainly an object that inspires odes, songs, and ballads.

After the New Horizons’ instrument overviews on the first day at the Pluto Science Conference (Jul 22, 2013, we jumped right into Pluto in the Kuiper Belt Context.

Brett Gladman (University of British Columbia, Vancouver, Canada) started the conversation by addressing “How does Pluto fit in our understanding of the Kuiper Belt?”

But before we get into that, discussing the Kuiper belt today can be pretty complex. It was only discovered in 1992, but in the years since, over 130,000 bodies with sizes 100 km and larger have been identified (Petit et al 2011), with Pluto being the largest member.

So when we start looking at large numbers of objects, it’s time to classify. So a typical plot to describe these “populations” is shown below, where semi-major axis (distance of body from the Sun) is plotted (horizontal axis, labeled ‘a’ in units AU, where 1 AU is the distance of the Earth from the Sun, Jupiter is ~5 AU, Saturn ~10AU) versus eccentricity (value between 0 and 1 that describes how circular an orbit it, e=0 is circle, e=1 is parabola, 0<e<1 describes ovals).

And then you have your Classical, your Cold Classical, Hot Classical, Detached, Resonant, and SDO (aka Scattered Disk Objects), etc. Sometimes they group together, others are more uniform across the parameter space.

Kuiper Belt in a/e space.” Cold classical (black open triangles). Resonant Kuiper (open red square). Detached (blue triangles). Pluto is indicated with the yellow-box, it’s a Resonant, as it is in 3:2 Resonance with Neptune. This group of objects, all in 3:2 Resonance with Neptune are the “Plutinos.” (that clumping around 40 AU, red triangles, spanning over a range of e). Resonance numbers are shown at the top of the graph.

Plutinos are also a family of TNOs, Trans-Neptunian Objects, characterized by being in 3:2 mean-motion resonance with Neptune (i.e., every time Neptune makes 3 trips about the Sun, the Plutinos make 2 trips). Plutinos are the most dominant of the TNOs. Less numerous are the 1:1 objects, objects known as Trojans.

Definitely KBO soup!

After getting down those nomenclature basics, Brett Gladman (who is also lead for a huge ground-based survey of KBOs called the Canada-France Ecliptic Plane Survey/CFEPS) discussed the strengths and pitfalls of the theories put forward to explain the formation and structure of this complex KBO menagerie.

How did Pluto get to where it is today? Two leading theories (1) Resonant sweeping of objects formed in TNO regions and (2) resonant trapping explain many things, but no published models explain those resonant structures of the Kuiper belt. And any of these models have issues with the classical and scattering disk populations as well. Theorists, better sharpen your pencils.

So he left us with questions to ponder. Is there a cold primordial Kuiper Belt with edge at 45 AU? Did Pluto likely form as one of hundreds to thousands of >1000km embryos? Did some of these become implanted into the nearby non-scattering belt? Are there others out beyond 100 AU (considered likely, but to discover them, you need to get down to 23-24th mag which is beyond the current survey capabilities until new telescopes and.or techniques come available)?

No doubt, searches for more TNOs will continue, the classification of the KB will undergo evolution, and theorists will refine their models. And New Horizons will provide a unique data set of an up-close-and-personal visit to Pluto and its companions to help constrain those models.

Putting Centaurs and TNOs in Context. This time plotting inclination (the degrees from the ecliptic plane) vs. semi-major axis in AU. Object sizes are reflected in the symbol sizes. Location of Saturn, Uranus and Neptune are shown. Just another way to look at that awesome & diverse Outer Solar System. From: https://en.wikipedia.org/wiki/Trans-Neptunian_object.

Next, Cesar Fuentes (Arizona State) phoned in about his work on the “Size Distribution (SD) of the Kuiper Belt.” Size distribution is basically counting the number of objects as a function of size.  Coagulation (of small particles) and gravitation instability (of larger particles) shape the size distribution. Size distribution is expected to change due to collisions. Different distances from the sun also appear to have different size distributions.

He stepped us through recent size distribution models from Schlichting, Fuentes & Trilling (2013) and Kenyon & Bromley (2013) where they even have some including the “collisional factor” influence on the size distribution over time periods.

All the Size Distributions show a “rollover” around H~9, D=70km. Nesvorny et al. 2013 investigates this further. Is the break due to collisional and therefore separate the primordial from the evolved KBO populations?

Even more questions to ponder:  Can we use size distributions to evaluate primordial from the evolved KBO populations?

And then he left us with a tantalizing experiment with the New Horizons mission: If New Horizons can provide data sets enabling “crater counting,” we will be able to measure the impactors on Pluto. This can aid in understanding KBO populations, addressing specifically, formation time, timescales for surface activity, and origins of bodies like Nix & Hydra. What would a 0.1-100 km impactor size distribution look like?

Pluto, be it Prince of the Plutinos or King of the Kuiper Belt, will always remain a key part to these questions above. And data sets from New Horizons will provide many new angles to answering questions about “Where did Pluto form and why did it wind up where it is now.”

Introducing the New Horizons Instrument Menagerie.

During the first day of the Pluto Science Conference, being held July 22-26, 2013, in Laurel, MD, the conference participants listened to a series of talks describing the rich instrument suite aboard the New Horizons Spacecraft. This entry is just a very brief synopsis of the instruments.

Ralph, Alice, MVIC, LEISA, LORRI, REX, SWAP, PEPSSI, SDC. Those are instrument names and acronyms of the New Horizons science instruments.

New Horizons Instrument Suite at a Glance.

LORRI (Long Range Reconnaissance Imager), among many things, “Enables Far-Out Encounter Science. ” That is, at 10 weeks from closest approach, LORRI can observe the Pluto system with spatial resolution better than Hubble. It is a visible camera, equipped with a 1024 x 1024 pixel CCD, with a 0.29 x 0.29 degree field of view (5 microradian pixel iFOV). LORRI also will be used, on approach, for optical navigation. The LORRI Instrument Principal Investigator and Instrument Scientist is Andy Cheng (JHU/APL) and Hal Weaver (JHU/APL), respectively.

Ralph & Alice form New Horizons’  “Remote Science Suite.” Ralph is both a color-imager (MVIC) and an infrared mapping spectrometer (LEISA). Alice is a ultraviolet spectrometer.

Ralph’s MVIC (Multi-Spectral Visible Imaging Camera) consists of seven independent CCD arrays. Four channels are filtered to map blue (400-550 nm), red (540-700 nm), near infrared (780-975 nm) and a narrow methane absorption band (860-910 nm). Six of the MVIC arrays (including all the filter channels) have a 5.7 x 0.037 degree field of view (20 microradian pixel iFOV). LEISA (Linear Etalon Imaging Spectral Array) is a grating spectrometer covering 1.25 to 2.5 microns wavelength range at a resolving power of R~240. A second segment covers 2.1 to 2.25 micron range with a resolving power of R~560. The Ralph Instrument Principal Investigator and Instrument Scientist is Alan Stern (SwRI) and Dennis Reuter (NASA Goddard), respectively.

Alice is an ultraviolet imaging spectrometer. It has two entrance apertures, a large airglow channel and a small SOCC aperture for solar occultation measurements. The entrance slit has two sections, a “box” with a 2.0 x 2.0 degree field of view, and a “stem” with a 0.1 x 4.0 degree field of view. The wavelength coverage spans from 520 to 1870 Angstroms, with a resolution of 3.6 Angstroms.  The Alice Instrument Principal Investigator and Instrument Scientist is Alan Stern (SwRI) and Maarten ver Steeg (SwRI, San Antonio), respectively.

REX, New Horizons’ Radio Science Experiment, is enabled by adding a small amount of signal processing hardware to the existing communication hardware on New Horizons’ main antenna. It will be used, among other observations of Pluto, to showcase a “Different Kind of Radioscience” via 20kW uplink experiments from the DSN during the Pluto and Charon occulations at flyby. The REX Principal Investigator and Instrument Scientist are G.L. Tyler and Ivan Linscott (Stanford University), respectively.

PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation) & SWAP (Solar Wind Around Pluto) are modern particle instruments designed to capture Pluto’s interaction with the solar wind. PEPSSI can measure ions and electrons from 10s of keV to 1 MeV over a 160 x 12 degree fan-shapped beam. SWAP can measure particles with energies 35 eV to 7.5 keV over a 276 x 10 degree field of view. PEPSSI’s Principal Investigator and Instrument Scientist are Ralph Mcnutt (JHU/APL) and Matthew Hill (JHU/APL). SWAP’s Principal Investigaor and Instrument Scientist are David McComas (SwRI, San Antonio) and Heather Elliott (SwRI, San Antonio).

SDC, the Student Dust Counter, designed and built by students at the University of Colorado, Boulder, is “The First Student Experiment on a Deep-Space Probe.” The Principal Investigator is Mihaly Horanyi (University of Colorado). There have been numerous Instrument Scientists, all students at Univ. of Colorado. The current Instrument Scientist is Jamey Szalay. Students continue to be active in supporting data analysis as SDC collects dust rates on its voyage through the solar system. More information about the SDC and the students behind it at http://lasp.colorado.edu/sdc/.

More details about each of the instrument descriptions and performance can be found at http://pluto.jhuapl.edu/spacecraft/sciencePay.php

Locations of the science instruments on the New Horizons Spacecraft

The Architecture of New Horizons’ Pluto Fly-By Sequence.

In her presentation at the Pluto Science Conference, Dr. Leslie Young (SwRI), deputy Project Scientist and chief architect of the Pluto Encounter Sequence, stepped us through the New Horizons’ Science Objectives and the types of observations that will be pre-programmed aboard the craft for the entire year of 2015. Unique science is not just around Pluto Closest Approach on Tues, Jul 14, 2015, but many months prior and post the encounter. Although most of the “Group 1” (see below for description) science objectives for the mission will be met by measurements made in the -2hr to +3hr from closest approach. Closest approach is on July 14, 2015.

Leslie Young (deputy Project Scientist) describes the overview of the science highlights for the year 2015. Also shown in the slide is a mapping of the Science Objectives per each phase.

Science space missions typically have a set of “science requirements,” specific measurements to address specific questions, set forth to be met by the mission design. The main science questions that the New Horizons mission is designed to answer were asked in the proposal call (AO 01-OSS-01) that NASA put out in early 2001, the competition which the New Horizons team won. The proposed series of measurements that New Horizons will do with its instrument suite provide measurements to answer Group 1, Group 2 or Group 3 objectives. Group 1 are measurements that must be done and define baseline science mission success. Group 2 are highly desired measurements and Group 3 are desired measurements. To obtain data that meets Group 1, 2 & 3 measurements is full-science success.

That single slide that Leslie showed (above) is the sum of many, many, many months of work with the New Horizons Science Team, along with support from the project’s Mission Design team, to identify which measurements of which body at which time (or times), as an ensemble meet the Group objectives. She specifically calls out the Group 1 by showing those categories in Bold Italics.

As the New Horizons Science Fly-By mission is a temporal series of measurements, the mission has been constructed to compartmentalize the measurements as a function of day from the closest approach. Hundreds of unique measurements are scheduled in rapid-formation within the day prior and after closest approach, called the NEP or Near Encounter Period.

Some Pluto Encounter Design Temporal Terminology:
AP= Approach Phase, NEP=Near Encounter Period, DP=Departure Phase
AP1: Jan 6-Apr 4, 2015, P-180 to P-100 days to Closest Approach
AP2: Apr 4-Jun 23, 2015, P-100 to P-21 days to Closest Approach
AP3: Jun 23-Jul 13, 2015, P-21 to P-1 days to Closest Approach
NEP: Jul 13-15, 2015, P-1 to P+1 day from Closest Approach
DP1: Jul 15-Aug 4, 2015, P+1 to P+21 days from Closest Approach
DP2: Aug 5-Oct 22, 2015, P+21 to P+100 days from Closest Approach
DP3: Oct 22, 2015-Jan 1, 2016, P+100 to P+180 days from Closest Approach

Leslie Young describes the mission science measurements on a timeline near closest-approach. The instruments are color-coded in this representation of the distance to Pluto (y axis) vs. distance from Earth/Sun (x axis) with respect to the closest approach (nominal July 14, 2015 11:50 UTC). A larger version of that slide is shown below. The x-axis spans 5 hrs of time.

Below is a summary of the best spatial resolution measurements anticipated from New Horizons’ Remote Sensing Suite within a few hours of closest approach. Panchromatic (LORRI camera), Color (Ralph MVIC), and Infrared (Ralph LEISA) resolutions are shown against each target body for the closest-distance to those target bodies in the nominal sequence. The science requirement for the equivalent Group 1 objective is shown in italicized text.

With our current best resolution of Pluto spanning 100 km/pixels taken with the Hubble Space Telescope, the New Horizons mission with its up-close-and-person will rewrite the textbooks on this elusive system with more than 2 orders of magnitude resolution improvement, plus spectral, radioscience, and plasma unique measurements.

Our best on Pluto from Hubble can be found form these links for observations taken in 1994 & 2010:
http://hubblesite.org/newscenter/archive/releases/1996/09/image/a/format/web_print/ and http://hubblesite.org/newscenter/archive/releases/solar-system/pluto/2010/06/, respectively.

Calling for proposals to observe the Pluto System from Earth and Earth satellite-assets! “As planetary astronomers, we love phases” as Rick Binzel (MIT) describes “Earth-Based Observing Campaign for the New Horizons Encounter.” We’re going to need to make a link to connect decades of earth-based observations of the Pluto system before the fly-by and continue it for decades after the New Horizons fly-by. There is a website set up for information on how to participate and get more information. Specifically observations are needed in 2014, 2015 (encounter year), and 2016.

The website will be based at http://www.boulder.swri.edu/nh-support-obs/ . Check back later since they are actively working the content, but you can always email nhobs “at” boulder.swri.edu for information.

Rick Binzel also introduced the campaign to get a Lego set made of the New Horizons Spacecraft. It needs to vote to get it approved for production. Note: this requires you to register for free-account to log in to vote. http://lego.cuusoo.com/ideas/view/44093.

Summing up the first session of an exciting beginning to the Pluto Science Conference,  per Alan Stern, the Principal Investigator for NASA’s New Horizons’ Mission: “The most exciting discoveries will likely be the ones we don’t anticipate” and  “Revolution in Knowledge is in Store.”

Initial Reconnaissance of the Solar System’s Third Zone.

This is part of a blog series on the Pluto Science Conference, “The Pluto System on the Eve of Exploration by New Horizons: Perspectives and Predictions,” held July 22-26, 2013 in Laurel, MD.

New Horizons’ Principal Investigator (lead scientist) is Dr Alan Stern (SwRI/Southwest Research Institute). In his presentation, he gave an overview of the mission concept, the science objectives and mission status. The scientific suite is sophisticated and carries the first student-built deep space instrument. The cruise period spans two Presidential administrations (8 years). New Horizons launched on January 19, 2006, and will fly by the Pluto system with closest approach July 14, 2015. For more information about the mission, do check out the New Horizons Mission Websites: http://pluto.jhuapl.edu/ (JHU APL site) and https://www.nasa.gov/mission_pages/newhorizons/main/index.html. (NASA site).

At a glance, the New Horizons Mission to Pluto and Beyond. Key milestone dates and the spacecraft trajectory (in red).

Measurement-wise, New Horizons’ Pluto fly-by of July 2015 is comparable to Voyager 2’s fly-by of Neptune’s moon Triton in 1989. However, Voyager 2 did not have an infrared mapping nor ultraviolet imaging spectrometer, something New Horizons will have. Also, New Horizons will be flying three times closer to Pluto than Voyager 2 did at Triton.  A snapshot of the comparison highlights from Alan’s talk is below.

Comparison of Voyager 2 data from its fly-by of Neptune’s moon Triton in August 1989, with a “visualization” of what New Horizons’ best resolution at Pluto might reveal during its fly-by of Pluto in July 2015.

The New Horizons’ unique science encounter involves more than 6 months of active science operations, starting in mid-April 2015 when the on-board instrument suite achieves resolution better than Hubble.

A more in depth discussion about “When will New Horizons have better views of Pluto than Hubble does?” can be found in this blog entry on the Planetary Society’s blog site at http://www.planetary.org/blogs/emily-lakdawalla/2013/0218-new-horizons-pluto-better-hubble.html .

For more in-depth information about the New Horizons mission check out a series of a papers published in Space Science Reviews.  Link: http://www.boulder.swri.edu/pkb/

To end this posting, a few fun factoids about New Horizon’s Speedy Performance since Launch.
New Horizons’ Speed Record. Launched on an Atlas V-551 on January 19, 2006 at 14:00 EST, the ~400 kg spacecraft, about the size of a grand-piano, needs to travel 5 billion km (5x10e9 km) from Earth before it can execute the observations for its prime science mission. Launching with a speed of  58,000 km/hr (36,000 mph) and benefiting from a gravity-assist from Jupiter in February 2007 (which boosted the spacecraft speed), New Horizons will reach its destination, Pluto, after ~9.5 years of space flight.

New Horizons Speed Facts:
Launched at 36,000 mph
Passed Moon’s orbit in 9 hours
Passed orbits of:
Mars on 4/7/2006
Jupiter on 2/28/2007
Saturn on 6/8/2008
Uranus on 3/18/2011
To cross orbit of:
Neptune on 8/24/2014
With closest Approach Pluto-Charon on 7/14/2015

New Horizons, a mission for the patient (and persistent).

New Horizons is a Mission for the Patient (and Persistent). It is a labor of love, dedication, fortitude, with compelling science, top-notch engineering, and tight management. This is an entry part of a blog series covering the Pluto Science Conference, held July 22-26, 2013 in Laurel, MD.

Tom Krimigis (JHU/APL) started off our excited Pluto crowd with an overview of the steps that enabled the New Horizons mission to become reality. Any science mission starts with its science objectives. Successful science mission concepts that make it to launch rely on thorough reviews of its science, engineering, and investment (i.e. cost & feasibility).  New Horizons, owes its existence to both initial scientific grounding work by the scientists in the 1970s and equally also to the persistence of those scientists and supporters at NASA and Congress over the subsequent decades to make it get to flight. New Horizons was selected in November 2001 from a competition and launched in January 2006. It will reach its destination, the Pluto-Charon system in 2015.

A rose by any other name is still a rose. A mission to Pluto has had many names over these past decades and with concepts “varying on a theme.” It was called Mariner-Jupiter-Pluto (MJP), mini Voyager-Pluto Fast Flyby (PFF), Pluto Express-Pluto-Kuiper Express, and now New Horizons, among many mission names.

For more reading about the saga, science, and significance of Pluto exploration, check out Andrew Lawler, Science 295, 32-36, Jan 4, 2002. “Planetary Science’s Defining Moment.” at http://www.sciencemag.org/content/295/5552/32.full.pdf  (requires login access) or find it herefrom the author’ website here.

Pluto Not Yet Explored (lower right) from USPS Stamp Series (1991)

Introducing the Pluto Science Conference July 22-26, 2013.

The mind of a scientist understands, embraces, and executes the scientific method, the process by which an idea is created, then tested by experiment or model, validated or refuted, and then, when validated, culminates in the description of the results to the larger community through a publication. The cycle begins again, sometimes building on previously published work, or in some cases, the birth of new ideas to the scene, most likely inspired by previous knowledge.

A key component to a scientist’s work is the attendance and interaction with colleagues at scientific conferences. At such gatherings we can see examples of the scientific method in a multitude of stages: the birth of a new idea, the suggestion of methods to carry-out the experiment or computation, a presentation that disproves an approach requiring the scientist to start anew, through the description of the results of the recent experiment or computation.

~150 people are to gather this week at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD to share ideas, debate hypotheses, and explain experiments related to the emissary from our Solar System’s Third Zone, the dwarf planet Pluto and its moons. The timing is crucial to have these conversations because in two years from now, in July 2015, NASA’s New Horizons Spacecraft will do a close fly-by of the Pluto system, a system never before visited by another spacecraft. The forum provides an update of the mission and its measurement capabilities and encourages healthy dialog among theorists who have predictions, laboratory spectroscopists who can build examples of chemistry happening on these icy bodies, and observers who have been monitoring and documenting the changing nature of Pluto and its environment.

Details about the Pluto Science Conference, “The Pluto System on the Eve of Exploration by New Horizons: Perspectives and Predictions,” can be found here at
https://dnnpro.outer.jhuapl.edu/plutoscience/Home.aspx.

You can follow the New Horizons mission status at any time by visiting the New Horizons Mission Website at http://pluto.jhuapl.edu/ and https://www.nasa.gov/mission_pages/newhorizons/main/index.html.

I’ll be providing summaries of the meeting content and discussions through a series of blog posts this week. For now, I’ll leave you with some things we do know about Pluto and its largest moon Charon.

The diameters of Pluto & Charon shown with respect to the USA for scale.

What do we know about Pluto so far?

• Highly elliptical (e = 0.25), Highly inclined (i = 17 deg), 248 year orbit
•  Rotational period of 6.387230 days
•  Small (diameter = 2328 ± 42 km), Rock/Ice object (“Icy Dwarf”)
•  Density is 2.03 ± 0.06 g cm-3, Mass = 0.0022 MEarth
•  Bright surface frosts of N2, CH4, CO, and C2H6  produce albedo of ~55%
•  Highly variegated surface (bright and dark regions)
•  Reddish in color, probably due to surface organics
•  Tenuous, variable atmosphere (mostly N2; 2-10 µbars at the surface & going up)

What do we know about Charon?

• Discovered, by accident, in July 1978 by James Christy (USNO)
•  In circular orbit ~19,573 km from Pluto, with a 6.3872273 day period
•  Tidally-locked spin period (i.e., spin-orbit synchronous)
•  Diameter is 1212 ± 3 km (about half of Pluto’s Diameter: “Binary Planet”)
•  Density is 1.66 ± 0.06 g cm-3 (vs 2.03 ± 0.06 g cm-3 for Pluto)
•  Surface has crystalline H2O-ice and NH3-hydrate (recent?)
•  Average albedo ~35%, neutral color (variegation change over time?)
•  Average T ~ 50 K, low thermal inertia (high porosity)
•  No atmosphere detected yet (~10-300x lower pressure than Pluto’s)

(left) Charon Discovery Image July 1978; (right) New Horizons’ LORRI instrument spots Charon July 2013 from 6AU away.

To Pluto and beyond!

Reflections on flying on SOFIA. I totally got the SOFIA bug.

Tonight, Thurs Jun 13th was to be a second opportunity for me to fly and test the FORCAST grism suite on SOFIA. However, that flight had a RTB or return to base, due to an aircraft item that manifest itself inflight. The pilots were awesome and returned us back to Palmdale, CA, safely.They followed their checklists and since most of tonight’s flight was to be thousands of miles over the Pacific, return to base was the right course of action. The flight is now rescheduled for next Tuesday. I am hoping I can remain on the passenger manifest and I can always do remote support.

For those who follow the SOFIA story, it has been a longtime coming. But you just have to admit it, SOFIA is just cool. First of all,airplanes are cool. 747s are even cooler. And to have a hole cut into a 747 to outfit it with a telescope that can point, even in turbulence, is just the coolest of coolness. I know I always knew that, but in all honestly, I did not realize it until I experienced it. I hope you have enjoyed my blog updates on this experience.

SOFIA is also an amazing piece of engineering. If you think about it, a lot of engineering has gone into the airplane, the modifications to support the telescope, the telescope design and operation, all the different science instruments, and the support infrastructure to make it all happen.Thanks to all the people who made this unique observatory possible, and those that are working hard today getting it operational.

For those astronomers out there, a call is on the street for science observing on SOFIA. Proposals are due Jun 28th, 2013 for the 2014 observing cycle.  http://www.sofia.usra.edu/

For those interested in applying to be SOFIA Airborne Ambassadors, definitely check out that amazing program. The current application period is closed. But check in the future for the next call.

http://www.seti.org/sofia

SOFIA is a powerful observatory. Its legacy is about to happen. There are not many telescopes out there that can access the infrared skies. By flying above the water vapor in our atmosphere, the infrared sky is revealed to us. Of course, our eyes cannot see such wavelengths, but our infrared detectors can. We can use these tools on SOFIA to answer questions about the formation of the stars and galaxies and their evolution. SOFIA with its 20 year lifetime and its mobility to be operated from anywhere on the planet that has a runway, has only yet to contribute to understanding of what’s out there. It’s an excellent training platform for students and teachers. In fact, on the line ops and the flights I was on, teachers and undergraduate and graduate students participated. What a great opportunity for a grad student to have access to this state-of-the-art telescope! The four I have met these past few weeks are so jazzed about what they are going to observe with SOFIA.

SOFIA after the successful completion of Flight#105, the morning of Jun 12, 2013. We got over 8 hrs of time at >= 40,000ft checking out the modes to commission the FORCAST mid-infrared camera with grism complement.

I still have work to do on my small role in the SOFIA story. We collected some (not all) of our grism commissioning data. With next week’s flight, we aim to fill in those gaps. I have data now to reduce and check out our quicklook pipeline that we are tailoring for the observers who request to use of grisms to do their science. And, that long awaited paper on the actual performance of these novel infrared optics I helped develop is now in the works!

I look forward to flying again on SOFIA, as an observer. I have a few ideas of neat things to observe.

I close my blog series with an amusing observation. On my Jun11th flight, I spent most of my time facing the science instrument/telescope area, which is, towards the rear of the plane. I was standing a lot, and occasionally would sit down at the conference area mid-deck to do some data reduction. All that time I stood watching the telescope, participating in discussions about the data, etc. looking aft, I realized I was journeying on SOFIA, as viewed by someone outside the plane, backwards.

Terry Herter (Cornell), FORCAST Principal Investigator & many-time SOFIA flyer, remarked to me, “After a few minutes in the air, you forget you are in an airplane.” And that’s precisely that. I thought I was observing at a telescope observatory.  The only drawback: I could not walk outsideto look at the stars, as I just love to do when I am a dark site, like at an observatory. But that’s okay, I was using state-of-the-art instruments to look at the stars with a different set of infrared eyes.

I’m not sure how the comments section on these blogs work, but I’d be happy to answer any questions. Just drop me a line.  Kimberly.Ennico at nasa dot gov.

The blog author aboard SOFIA during take off on Jun 13, 2013. Notebook in hand. Mind on the targets we were to observe that flight. Smile for the adventure and learning ahead.

Time management at 40,000 ft. The temporal realities of an airborne observing flight.

So between takeoff at 7:25pm PDT and landing at 5:25am PDT,the flight planners had to keep us literally on track. There is an official flight plan that the pilots will follow and which has been worked out ahead of time with FAA air traffic control. It’s the result of a complex optimization strategy to calculate where one’s targets are in the sky and visible by the SOFIA telescope at given times and locations of this moving airborne platform,along with ensuring not entering no-fly areas, and of length and elevation appropriate for the amount of fuel on board to enable a 10 hour flight, with about 8 hrs at the desired 40,000 ft elevation. In addition, they need to look at seasonal weather patterns, and then on the final iteration of the flight plan, they take into account the most recent weather predictions. In ground-based astronomy,you can lose time on your objects by being “clouded out.” For airborne astronomy when you are above the clouds, your only threats to observation time are weather-related, but weather of another kind.

http://www.sofia.usra.edu/Science/workshops/SOFIA_Workshop_2011/docs/705_FlightPlanningWSNov11.pdf

http://www.sofia.usra.edu/Science/proposals/basic_science/FlightPlans_current.html

Thus, you want to be smart to make the use of this unique facility flying in the skies getting you incredible access to the infrared wavelengths. So when our test plan was created, for each leg, we had prioritized which observations we needed to get done, our “baseline” versus observations of “the nice to have” flavor.  In case we lost time, we aimed to achieve that “baseline.” In case we were more efficient with setting up each observation than originally predicted, we might have more time to tackle the “nice to haves.” In ground-based astronomy where you don’t have such a tight timeline, unless of course the sun is rising or your object has gone below the horizon, you could easily extend your observations by a few minutes or so. For SOFIA, they do keep the leg duration strictly flown as planned with little room for time extension.

For Flight#105, we had 13 legs, of which legs #6-12 were“science.” Legs 1-5 were the ascent legs to get up and out of the LA congested airspace and get us to altitude.  Leg 13was the final descent back to Palmdale, CA. As I mentioned in the previous blog, within a few minutes after takeoff, even while we were still ascending at an angle, we were allowed to get up and walk about the aircraft. We used this time to get our computers and laptops all set up. The telescope operators got the telescope (the door is closed) up and running ready to go when the conditions allowed for the door to open. Actually on flight #105, we had to delay the door opening until we got above some high-altitude cirrus clouds, but it did not impact significantly the post-door opening telescope checkout in time for when we got on our 1st target.

Image of the science instrument & telescope guide game consoles between flight legs.

We stayed all configured even as SOFIA turned between legs.You can see the computer screen on the right is the telescope guide cameras and the streaks are just stars going through the FOV.

The Flight Planner’s voice was a welcome reminder of the essence of time management. She did not speak that often, but often enough to put in reminders “30 minutes left on leg, 10 minutes left on leg,” etc. So when we started to deviate slightly from the observing plan because the script did not work, or the telescope lost lock on the target, etc. and you found yourself easily losing track of time, she grounded us back to the timeline. Our lead instrument scientist, Jim De Buizer, had to make calls on the fly to get back on track to accomplish the tests per leg. It’s a tough job to stay flexible but creative with how to get things done. And when you lose 10 minutes or so to turbulence, you have to re-insert yourself into the observation timeline to keep ticking off the tasks.

The Flight Planner was also in constant communication with the pilots who were talking with air traffic control to look at flight conditions. So another task she did was ask us about some possible real-time deviations for the next leg to “fly around weather” but still stay in the same area of the sky so that the observations were not affected (significantly). The net result is that you might lose some observation time up front at the trade of not having interrupted observing downstream. That was an interesting trade to see happen. And yes, on SOFIA Flight #105, when we were over the Dakotas and Kansas we had to do two deviations due to weather, but we managed to still get most of the data for those legs as a result. Had we not deviated, we most likely may have lost the entire leg’s observation.

View from the Mission Director and Flight Planner’s console.

The central image shows a live view of where the aircraft at the specific time and also shows (by different colors) alternative flight trajectories in case the aircraft needs to divert for weather. Diverting due to weather happened two times on SOFIA Flight #105.

If you noticed in the pictures I posted, we are wearing headsets. There were not enough headsets for all passengers, so we traded off.The sound inside is like a typical 747 aircraft, maybe a bit on the noisier side (lots of computer racks and not much fabrics to absorb sound), but perfectly fine with ear buds. However, wearing the headsets and monitoring the channels helps immensely to know what is going on. There is no “Bleep. Please return to your seat” automated voice from above, but rather the Mission Director saying on the communication (comm) system “Guys, it’s time to sit down now.” And there is no “call-button” for assistance, you just talk where you are through the headset.

Typical view of operations during a SOFIA observation flight

Typical view of operations during a SOFIA observation flight. We’re wearing headsets to communicate between all the stations on the aircraft.

Getting back to headsets…it was quite fun, since part of the flight I was sitting at the “conference table” at mid-deck and we were just chatting with the science instrument folks who were near the telescope as if we were across the table. It was very efficient. We could stay at the “conference table” with our laptops hooked to the on-board internet doing the data analysis and report things we saw in the data to our colleagues who were more focused on trying to take the data and keep to the script schedule and interact with the telescope operators who had to do lots of telescope rewinds and target re-acquisitions.Plus, having this arrangement, kept people from crowded at the consoles. Of course, from time to time I wanted to be “at the action” and I would walk and re-plug in my headset up front if a port was open.

Doing data reduction between legs on SOFIA observing flight

The photo above is Luke Keller from Ithaca College, sitting down with laptop, doing some grism 6 data reduction between legs. It was a good thing to share the flight with the imaging team as when they had an image intensive leg, we could escape and look at our data with our data reduction tools.

View from the science instrument consoles during an observation.

Screens from left to right are: FORCAST control,  FORCAST quick-look image display, Telescope Assembly Status Page, and the Guide cameras.In this image, we are executing a short chop of a point source.

So from our instrument scientist’s log, we had 16 tasks planned over the 6 science legs. We successfully completed 10/16, partially completed 5/16 (mainly due to lost of time from turbulence), and did not complete 1. Or about  88-90% completion rate, depending on how you count it. We’re learning as we go. We’ll use this information from this commissioning flight to improve our observing efficiency during science flights. But remember, these commissioning flights are designed to help us work out the basic modes and capabilities of the instruments and things are expected to not go as 100% as expected.

We have one more commissioning flight Thurs Jun 13th during which we will attempt to do cleanup from Tues’ flight plus address the tasks we had set for that flight (different flight plan is planned as we have different targets).

NGC7027 the “big glazed donut in the sky.” Observing a yummy wavelength calibrator source on SOFIA

On Leg #7, between 9:45pm PDT (04:45 UTC) and 10:49pm PDT(05:49 UTC), the pilots flew SOFIA along a leg going southeast from middleMontana to northeast Colorado. Our target was NGC7027, a planetary nebula. Ithas a distinctive ring shape, and a frequent wavelength calibrator for infraredinstruments due to having very strong emission lines.

Jim Debuizer, the USRA FORCAST Instrument Scientist, andtest lead for these commissioning flights, affectionately called it the “thebig glazed donut in the sky.” Perhaps he was getting a big peckish?

NGC7027 is a young, and rather dense planetary nebula. It’s notparticularly large on the sky, with its brightest region measuring about ~8arcseconds across in the optical. It’s located about 3000 light years away inthe constellation Cygnus (coordinates 21h7m1.7s RA, +42d14m11sDec). Most planetary nebulae are more extended, covering several arcminutes onthe sky. (As a calibrator note, for those who don’t speak arcseconds: the fullmoon is 30 arcminutes or ½ degree on the sky; 1 arcsec is 1/60th ofan arminute.) SOFIA’s FORCAST mid-IR instrument has roughly a platescale of0.75 arcsec/pixel. Thus, NGC7027 would appear to be ~11 pixels in diameter onthe FORCAST detector. For our grism spectroscopy, we are testing 2.4 arcsec(3.2 pixel) and 4.7 arcsec (6.2 pixel) wide slits, so NGC7027 would essentially“fill our slit.” Thus it would not be a great flux calibrator object as we’dhave “slit losses” but it’s infrared spectrum has well-identified andwell-spaced emission features that would be useful for our wavelength calibrationtask.

NGC7027observed by the Hubble Space Telescope. (left) Near-Infrared NICMOS image.(right) Composite visible & near-IR image.

http://apod.nasa.gov/apod/ap980325.html

http://hubblesite.org/newscenter/archive/releases/1996/05/image/a/

Imageshowing data reduction of an image of NGC7027 aboard SOFIA Flight#105

Above is an image of our quicklook pipeline as Iwas processing an acquisition narrowband image (at 11.1um) on SOFIA Flight#105. We used this image to confirm we placedthe target in the slit. The team was also testing out SLITSCAN, anobservational mode that would be used on SOFIA when observing an extendedobject using the grism suite. The positive and negative images are the resultof the chop-nod observing technique used to remove the background.

For moreinformation about chopping & nodding on SOFIA, see my earlier post at https://blogs.nasa.gov/cm/blog/mission-ames/posts/post_1369351626283.html

Imageshowing data reduction of an IR spectra of NGC7027 aboard SOFIA Flight#105

Above is an image of our quicklook pipeline as I wasprocessing our R~300 8-14um spectra (not fully-calibrated). We still need toremove the atmosphere. The strongest atmosphere issue are ozone absorptions at~9.5 microns. The emission features of the nebula are shown in our spectra. Ifyou look closely at the 2D spectra on the left, you can see we aligned the slitto capture two edges of the disk, showing as two bright lines on the edges ofthe slit.

We were observing this object with our grism spectra suite. Wetook data on this same object last week and started to use it as a sanity checkon our in-progress flux calibration in addition to a wavelength calibration. Belowis an overlay of two of our grisms (5-8um and 8-14um) with the spectra ofNGC7027 as observed by ISO years ago. We now have spectra to cover 17-28um and28-34um, and are working on their respective calibration steps. We are usinganother well-studied source, Arcturus (AlphaBoo) as our flux calibrator. Thereason why the 8-14um spectra in the image below is off is because the data setwe took was near-saturation so our various conversions were not optimal. Werepeated the observations at lower exposure to repeat the exercise.

Our working comparisonof our short wavelength grism suite data of NGC7027 with previously publishedobservations by the Infrared Space Observatory.

It was unfortunate that during this leg (Leg #7) that we hitturbulence and had to stop observing for a few minutes. We got slitscan(observational technique for extended objects) observation in (the goal of theleg), but sadly did not a requested long wavelength grism spectra of thisobject. However, we obtained other spectra on other objects using themissed-grisms later in the evening. It’s all going to be able piecing togetherthe puzzle now.

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

After boarding, we had some time before the doors closed. Asafety briefing was held. Upon entry to SOFIA, one objective, as this was arelatively “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 scatteredabout the airplane for specific purposes and prior to this flight, mycolleagues and I had worked out our seating. We could only send one representative to the “conference table” seatingarea, so Martin Garay (a student at Ithaca College) and I were sentto business class, while Luke Keller (our grism lead, astronomy professor atIthaca College) sat at the “conference table” midway along thetelescope deck.

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

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

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

The engines started at 715pm PDT (local time), and we tookoff around 7:27pm PDT. It was a good 50 seconds for takeoff. And essentially, itfelt 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 toget out of our seats. It was just so surreal to be walking down/up the planeduring the descent. It sort of felt wrong, as we are accustomed to the strict ruleson commercial aircraft, but it was so important to use any leg designed tobring the aircraft to the 40,000 ft science altitude, to do non-science thingslike setting up computers and testing connections between the systems. On thisflight, every second counts! And that theme was certainly reiterated throughoutthe night.

By 8pm PDT we were at 35,000 ft. The pilots had already completed3 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 scriptto check out the detector frame rate settings.

One of the first data acquisitionsof 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 tobe moving up/down/sideways, the telescope moved as well. It was mesmerizing tosee the FORCAST instrument and its counter weight moving about the cabin andyet the position of the star in the telescope guide camera was “rock solid.”Indeed, contents shifting during flight, but not this telescope! Two timesduring the light, the turbulence got bad enough that we had to return to ourseats 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 outuntil we can start observing again…)”

What was fascinating was that according to the missionmanager, we probably lost about an hour due to turbulence. We had to sit downabout 2x during the flight for a period of 10-15 minutes. I lost all track ofdurations of things, as I was focused on what data we lost by these unexpectedinterruptions. 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 fromour Leg #9 to avoid some baby tornado clouds. This time the timing was good aswe were doing some calibration flats which did not need a target so we couldstill take data during the diversion.

You can see what the actual flight path was by visiting http://flightaware.com and searching onNASA747.

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

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

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

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

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