Sunday, December 20, 2015

Gavin Gets an Answer

NASA reported first results from L1 at the 2015 AGU Fall conference.  The view from a million miles is amazing.  Eli has been following this saga, well from longer than the "pause", and actually since before there was an Eli. Monday was a press conference, Wednesday was a lap of honor for Al Gore and NASA.  Monday (video) and Wednesday last week were fine days in the sun.

This was a blessed mission.  Launch and orbital insertion went perfectly.  DSCOVR (the politically correct name for Triana aka Goresat) ended up on station with enough fuel to last until 2029 and the platform is considerably more stable than spec.  The plan was to have enough fuel to last 5 years.  One problem may be that the earth observing mission was set up for two years.  A usual problem with NASA satellites is that they last forever, or at least a lot longer than originally paid for.  The EPIC camera is operating close to if not at theoretical with a resolution of 35 km at the Earth's surface.  The solar array is putting out 600 W, twice the required 300 W.

EPIC is discovering things about aerosols and clouds that were not envisioned before launch such as tracking ships "contrails".  It will measure ozone profiles down to the surface, cloud height, UV reflectivity and vegatation cover.

The NISTAR radiometer has four channels. At the news conference most of the talk was about the simplest one, the photodiode which measures total reflectivity in the UV/VIS/NIR out to ~1.1 microns (the band gap for silicon detectors).  Not much was said about the other three channels, Band A the total radiation channel out to 100 microns, Band B which monitors the total solar light reflected from the earth (albedo) and Band C which captures the NIR solar reflected out to 4 microns.

Eli left out a considerable detail which bunnies can get from the video.

A while ago, Gavin Schmidt pointed out that to really measure the total emission from the Earth required a second DSCOVR on the other side at L2.  Wouldn't you know it, but somebunny at 35.30 asked that and by the way what is going on with Band A, the total emission channel   This, shall Eli say, resulted in a rather you answer that looking at each other among the panel, until Steve Lorentz picked up the ball.

With regard to a twin satellite, Lorentz who is a contractor, not NASA, and yes, he would be in favor

Well to the second one I would certainly entertain the possibility of trying to fly future missions of this type, but i am not the one who writes the checks for that.
There then ensued a couple of minutes of audio visual follies hunting for the back up slide which had not been shown.  Good news was that the Band A, B and C detectors are working,anddetectors can tell the difference between pointing at the earth and pointing at space.  Noise in Band A and B are well below the design goal of 1.5%.  Have to wait for next year for more

Which brings us to the Wednesday Gorefest. (Video here, but there may be hoops to jump through.  Ah yes, go here first and register, no fees or anything required, then follow the bunny trail)

Al Gore was quite generous in describing the hoops that DSCOVR went through before launch. He  still had his vision fixed on view from a million miles which all the Kool Kidz scoff at and please, this time in HD.

Adam Szabo, project scientist and chief of the heliospheric physics lab at Goddard Space Flight Center went a lot further.  He wants a second satellite at L1 with improved instrumentation including a spectrometer and an order of magnitude better set of radiometers AND a twin at L2.

Stuart (Whole Earth Catalog) Brand also plugged for DSCOVR L2, about the science and the awe that could be done from there.

So, Eli asks, why was the news conference so reticent or were they trying to cut somebunny off?  Only Gavin knows:) but still, no bunny is cutting checks.


Bernard J. said...

If this was a report card Johnny would be getting a big "Exceeds expectations", where the expectations were high to start with.

A lot of people are going to love Goresat. And quite a few are going to loathe it as it sails implacably over their heads - literally and metaphorically...

I wonder how Judy's satellite sensor comprehension is these days? Can I put a bet on a comment at some point about how there is - what's that word? - "uncertainty"?

Anonymous said...

One of the problems with a DSCOVR L2 bird is that it would be an entirely new bird. DSCOVR was resurrected after 8 years in mothballs, and it was a product of 1990s technology (and "Faster, Cheaper, Better"--pick any two).

Most of the parts on DSCOVR wouldn't even be available any more. This means DSCOVR L2 would likely be a better bird than DSCOVR, but it would not be a cheap bird to build.

EliRabett said...

Szabo and Al want two new birds:). Where that would come in the decienniel plan for Earth Science which is always a series of trades, Eli knows not, but they would have to carry a lot more instruments.

Anonymous said...

One can only wonder how many things like this (new satellites for L1 and L2) without having to endure the NASA nuttiness of SLS and Orion for well over a decade now. I hear there are a whole bunch of dangerous asteroids flying around out there too. NASA has really been on the ball, thankfully they have them all tracked by now, right?

E. Swanson said...

Sad to say, a satellite located at L1 isn't going to be able to measure the albedo at high latitudes with much precision. That's because most of the reflected energy is going away from the surface at a shallow angle, even when the orbit is at NH summer (or SH Summer 6 months later) solstice. Measuring emitted IR energy is also going to be similarly difficult. Basically, it's a problem with measuring what's happening around the edge of the visible field, (or limb), where the solar zenith angle is large. The old ERBE experiments used instruments which could not view energy originating from high zenith angle reflections/emissions and a model was applied to simulate the total emissions. I can demonstrate the problem with a GIF loop, but I've not placed it on the web.

Did the presentation(s) mention this problem? Is that one of the justifications for the satellite at L2?

EliRabett said...


If you can, try and listen to Szabo in the Wed. session, he would like to see many satellites, including L4 of the Earth Moon system. Since the satellites at L1/L2 are in Lissajous orbits the view could be enough out of the orbital plane to see the reflection from the poles

Anonymous said...

If only you knew. SLS and Orion are only the beginning of the nuttiness.

On the bright side, several proposals on tracking asteroids. And some folks are starting to pay a little attention. A few more meteors exploding over busy streets, and we might have something.


Why don't we give Goresat a nice calibration pattern of 35 km hydrosol ship wakes , so it can compare their albedo to E. hux blooms ?

EliRabett said...

Even better, if you listen to the news conference, DSCOVR can track rough sea surfaces by looking at reflectivity.


This we already do nicely with radar, as long as your mast is many wavelengths tall.

But I'll look anyway.

Hank Roberts said...

Eli, when you get to retirement, I hope you'll find time to start a DSCOVR chatroom/blog/newsgroup/twitfest (or whatever form is then popular) that would be, er, adequately dusted out regularly enough the real scientists would come chat with the rest of us.

I've tossed questions at the named contacts and gotten great info but figure they won't bear up if everyone asks individually, and answers to public view would be most welcome.

Like, how much to fund a Watcher of the Dark Side satellite?
I bet Kickstarter could do it just on the name alone (grin).
Especially if one of the space billionaires could become interested.

Like, is that gray-brown pall drifting east from India coal smoke?

Like, do they have an index of imagery so I could easily pull out pictures taken 24 hours apart (or as close thereto as possible) so looking at the same continent, to watch the Earth herky-jerky a day at a time-- continent more or less in the same place, so it's the clouds that jump forward?

For areas of interest within the view of geostationary Hindawari-8

it might be feasible to use that cloud data (live video) to interpolate between DSCOVR snapshots.
(Looking at Hindawari-8 it's very clear how damned much is going on in any given hour of time with cloud movements -- lots gets lost in between DSCOVR snapshots).

Hank Roberts said...

Oh, while the camera is operating at its expected resolution, the instrument cuts that resolution quite a bit by averaging four pixels and then transmitting one pixel for most images. That's controllable from the ground and some images have been at full quality. Then at the web page get the PNG not the JPG if you want the best available image.

That's from comments at the 'Networking' tab at AGU from one of the scientists who works on some other instrument on the satellite.

Hank Roberts said...

Is the AGU Annual Meeting streaming shut down now?

EliRabett said...

Seemingly not. Got in through this page

E. Swanson said...

I just finished watching the Wednesday session. Instruments at L2 and/or L4 might do the job, but they aren't in orbit yet and likely won't be any tine soon if one of the radical Republican party candidates is elected to be the next President. Gore's closing statement was heart warming, yet there remains a strong anti-science mood outside the cloistered compounds of the scientific elite.

There have been several commentaries about that sub-set of the electorate who would vote for Trump or Cruz and they may not be satisfied if the vote doesn't go for their chosen candidate. As a Southerner, let me say that the North thinks the War Between the States was over 150 years ago, but there are many country boys who think otherwise. HERE's a Commentary about how things got the way they are...

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