The New Horizons Kuiper Belt Extended Mission - arXiv:1806.08393

Paper: The New Horizons Kuiper Belt Extended Mission 
Authors: S.A. Stern, H.A. Weaver, J.R. Spencer, H.A. Elliott, the New Horizons Team
Abstract: The central objective of the New Horizons prime mission was to make the first exploration of Pluto and its system of moons. Following that, New Horizons has been approved for its first extended mission, which has the objectives of extensively studying the Kuiper Belt environment, observing numerous Kuiper Belt Objects (KBOs) and Centaurs in unique ways, and making the first close flyby of the KBO 486958 2014 MU69. This review summarizes the objectives and plans for this approved mission extension, and briefly looks forward to potential objectives for subsequent extended missions by New Horizons.

My Comment: Two and a half days before closest encounter, the extended mission target 2014 MU69 will finally be 2 pixels on the LORRI instrument. That's um... rather quick!

My Scrawling Notes:

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Back again.

It has been a long time since I updated this dead blog, but I think that will change, at least for a little bit. To get back into the swing of professional astronomy again, instead of just job and home hunting, I’ve made a commitment to myself to read and take notes on one astro-ph article that comes out each day. Will I always succeed? No, but I’m going to make this a habit. To that end I’ll be posting links to some of the papers I look at, a favorite bit of the article, and my hand-scrawled notes to this blog. That favorite bit might not always be sciencey, it might just be a comment or stat that I found rather amusing or fun.

As I get back into this habit I hope to also get back to writing a bit of stuff for this blog, but for now this should at least get the ball rolling on my current plan.

A year long Curiosity

Just a few quick thoughts.  This week marks the one year anniversary of the Mars Science Laboratory Rover, Curiosity, landing in Gale Crater on the surface of Mars.  A year ago we deposited a ton of nuclear-powered robot on the surface of another world. 

NASA/JPL-Caltech

Since then it is have been roving, scooping, dusting, vaporizing rocks, and just sciencing the heck out of the red planet.  36,700 images, 76,000 rock-zapping laser shots, and 1.6 kilometers driven so far.  It still has about an 8 km drive to go to get to the lower layers of the 5.5 km tall Mt. Sharp.  Just in it’s first year Curiosity has already a world that looks downright “habitable” in the distant past – spectacularly finding the remains of a pebbled riverbed.

NASA / JPL-Caltech / MSSS / PSI

So happy “birthday” to the MSL Rover Curiosity – may there be many more rocks to bother in your future.

Houston, Futura has landed.

I generally get a kick out of looking at the evidence of humanity that we have thrown around the Solar System, so with the Apollo 11 Moon landing anniversary just past I thought I would look at the the first words brought to the Moon by it – the Apollo 11 Lunar plaque.

Like all of the Lunar plaques brought by the Apollo missions this is a 9” x 7 5/8” stainless steel plaque, attached to the Lunar Module’s ladder.  It features the signatures of the three astronauts, the President on the United States, and a message of peace.  Classy look message eh?  You might recognize the lettering from the titles of Stanley Kubrick’s films, or more recently Wes Anderson’s work.  Like the Saturn V rockets that carried men to the moon, the font on the plaques they brought with them, Futura, was designed by a German.

Futura was designed by Paul Renner, and release to the public in 1927.  It’s a very clean geometric font.  No extra serifs, frills, or decorations are found. Now, I’m not a font expert by any means so I can’t go into the details of what exactly sets Futura apart from other fonts of the time, and how the various child-fonts it has spawned  differ from each other.  What I can say is that despite being a 86 year old typeface it still, to me at least, looks to the future, a future perhaps when the Apollo 17 plaque won’t be the last words we left on the Moon.



Right now this 41 year old plaque from Apollo 17 in an 86 year old typeface are the last words humanity personally left behind on the Moon.

Conjunction Junction, what's your function?

(My apologies to Schoolhouse Rock)

This weekend people around the world were treated to a very nice viewing of three planets all very close to each other in the sky.  An astronomical conjunction of the two interior terrestrial planets, Mercury and Venus, and the gas giant Jupiter.  Since I don’t want to get into the muddle of online digital image rights I took a screen capture of what the conjunction would look like from here in Virginia using the free open source planetarium program Stellarium.  You can tell it’s software since the planets don’t generally have large name labels when you look in the sky.



Neat huh?  All three planets are arranged in a triangle covering about 5 degrees of the sky (the whole pattern could be easily covered by your fist held at arm’s length).  Now this looks neat, but what is the importance of this event?  I mean while these planets are viewable together in a tightly compact portion of the sky they are still hundreds of millions of kilometers apart from each other and from the Earth.  What’s the significance?  Nothing… except the fact that we knew it was going to happen, and we can accurately determine when such alignments have happened in the past, and when they will happen in the future! 

For example, I can state with some certainty that the next time Jupiter and Saturn will be extremely close to each other in the sky will be on December 21st, 2020.  The last time these two gas giants were in conjunction was on May 31st of 2000.  Notice the time separation of 20 years.  This conjunction of Jupiter and Saturn happen about every 18 to 20 years because of the difference in times between the Earth’s orbit (1 year), Jupiter’s orbit (~12 years) and Saturn’s orbit (~30 years).  All of these worlds orbit round and round the Sun, and every now and then the math adds up just right and they are all in a line.  Not only do I know when this event will take place, but where it will be – the constellation of Aquarius.

Stop for a moment and think just how amazing that it that we can say such things.  We, people living on a small blue world, have the agency and know-how to accurately model, predict, and explain the motions of the planets, worlds unto themselves as they swiftly travel through space.  So what’s the significance of the conjunction?  Nothing but a beautiful demonstration of our exploration of the natural world around us.

Oh, and we’ve thrown robots at them as well.

Believing in comet dust

Well, I have a few things to add since my Comet Kerfuffle post a few months back.  Since then I've had the chance to take some images of comet C/2012 S1, aka Comet ISON through a fairly decent sized telescope (3.5 meter).  I'm starting to believe that we are in for quite a show this fall.  Why?  Well here's my reasons to be optimistic:


1.  At about 5 AU, where Jupiter orbits, the comet already has a very pronounced coma and tail.  This is still far enough out that it isn't getting warmed all that much by the Sun, and in fact not all of the gas species that drive the coma and tail have even reached sublimation temperature yet.  As one would would expect from an Oort Cloud object making a fresh return to the inner solar system, it is a very, very active comet.

Comet C/2012 S1 @4.9AU (Hammergren, Solontoi, Gyuk)

2. Its going to pass close to the Sun.  Really close.  Close enough that the tidal and thermal forces associated with the comet's passage by the Sun may cause it to fragment.  If that happens it will be quite a show for sure.  Unfortunately from the look of the orbit that event would most likely happen with the comet behind the Sun viewed from Earth.

3.  Folks who have been tracking the observed magnitudes of this thing are saying that it is fairly odd.  Most comets brighten suddenly and then "level off" at a certain point (if you're squinting at them in the right logarithmic axis!).  This one looks like it may have already gone through this change due to the way it is increasing in magnitude.  If that's the case it isn't a wild prediction to say that C/2012 S1 is trending toward "lunar" magnitudes - potentially as bright as the Moon!

Now I'm not saying that I am predicting that this is going to be a day-time comet - it will be hidden by the Sun when it is at perihelion for instance.  Many, many things can and will change in this comet's life between now and November of this year, but the way things are shaping up I am starting to really think that this comet will be spectacular in one way or another.

Adaptive Optics in my Basement

So recently I’ve been putting a bunch of thought into some interesting things to do with the Junior/Senior Optics course this Spring,  particularly the labs.  Given my own areas of interest and research, Astronomy, I was drumming my brain about how to incorporate that into the lab experience.  We’ll be going to the Belk Observatory to do some observing under the guise of telescopes are optics, but quite honestly I don’t want to turn the course into “how to build a telescope.”  Ok, I’ve joked with folks that the course’s labs will be one single project – get the new spectrograph working by semester’s end and they pass, but in seriousness I wanted something neat to do.

Absolutely one of the coolest bits of optical wizardry that has come down the pipe for astronomy is the idea of adaptive optics (AO); by making some form of real-time measurement of how the atmosphere distorts the light from a point source you (well computers) can send commands to movable and deformable mirrors and actually correct for the atmosphere.  This is a hugely great thing since the atmosphere (while nice for keeping us alive) is terrible for astronomy.  The sensors, computers, and deformable optical elements of an AO system, while expensive, are vastly cheaper than the “easy” solution – putting your telescope in space.  That’s one of the reasons why the Hubble Space Telescope (HST)  takes such amazing images with a modest 2.4-meter primary mirror, outperforming much larger aperture ground-based telescopes.  With AO systems the largest class of ground-based telescope can make observations that are much more “HST-like” in their angular resolution.

While I said these systems are vastly cheaper than going to space, they are still really pricey.  Even simple bench-top set-ups are costly, particularly since I’m not looking to even put it on a telescope, but rather have something for my students to poke at.  That’s when I got to thinking, and asked myself “is there a way to make a working model of this?”  And I stumbled upon something.

The heart of a particular class of AO systems is the ability to make a measurement of the wavefront of light that is being observed.  Without any sort of distortion this wavefront could be though of as “flat.”  When the light has to go through some kind of inhomogeneous medium, like our atmosphere, it gets distorted, with “bumps” getting added it.  A classic way of observing this wavefront distortion is through the use of a Shack-Hartmann Wavefront Sensor (SHWS).  The crude explanation of how it work is this:  The deformed light wavefront passes through a very fine grid of small lenses, or lenslets.  Each of these lenslets focuses the light independently of the others (they are, after all, separate lenses).  As long as these lenslets are small compared to the distortions they will make a sharp, in-focus, image.  The image from each of the lenslets will however be at a slightly different position with respect to the lens’ center because they are each “seeing” a slightly different wavefront since they each sample a very small portion of the overall “bumpy” wavefront.  If the distortions change with time (like the atmosphere) the images from each of the lenslets will drift around with respect to each other.  Instruments employing this method not only are used in AO telescope systems, but also in checking the quality of optics, and even examining the human eye!

So what?  These lenslet arrays are also really expensive, but what if I could be a cheap “macro-sized” version of it?  For a demonstration wouldn’t a grid of 9-16 small lenses be able to show this?  If I have an object to image far away, and let that light pass through such an array of lenses I should be able to produce 9-16 small images of the object.  By sticking something that disturbs the light between the object and the lenses I should be able to make the images wander around with respect to each other, just as in a SHWS!

Well, I tried it out.  I found and cleaned 9 small lenses in the physics lab, and brought them home to make a test run.

One of the lenses.

I then found a thick piece of styrofoam that I could make a crude lens holder out of.  The first hole I drilled in ended up being too big, even though the 1.5” bit should have made a hole slightly smaller than the lens itself (~39mm) - too much styrofoam chipped out.  I ended up drilling holes with a 1.25” bit that chipped out enough styrofoam in the end that the lenses could fit in snugly.

The Lens Holder Mark I is ready for action.

I stuck the lenses in, and holy moly, it worked!  I could make a 3x3 array of small images of an object on the other side of the room, and by moving a large, glass, floating candle holder between the object and the lenses, see that the crude wavefront sampling I was trying to get was actually, to a degree, happening!

An LED Christmas tree as seen through the lens array (left) and projected onto the wall (right)

This is way cool – my proof of concept works.  Now I need to make something a bit better to mount the array and I’ll be in business.  In it’s final form for the lab-demo I’m thinking of mounting it parallel to the floor, with the source object high above it and the lenses creating their images on a screen on the floor.  That way I can have an intermediate tray which I could put an irregular medium that the light would have to go through, a tray of water or other transparent fluid, or if it is sensitive enough we might only need a hairdryer or blow torch to stir up the air a bit.