Archive for April, 2009

Kepler Mission – Mr. Ian Bradley you have an answer

A question made by Ian Bradley arrived my e-mail via Stuart Atkinson, since there might be other Kepler fans with the same doubt I decided to bring it here:

Regarding the Kepler 1st light image…
 
The imaged area is well away from the ecliptic to allow 24/7 viewing of the image area without Sun being a problem. On a quick glance at the high res 23Mb image from the Kepler website, there are several diagonal tracks [not the vertical or horizontal blooming from bright stars]. One is particularly bright (see below for position). Are these earth orbit satellites (given that Kepler is in an Earth trailing heliocentric orbit, this seems unlikely) or are they other solar system bodies e.g. minor planets, asteroids, Keuper Belt objects etc, etc. I guess it could be crap from the spacecraft itself…
 
Clearly they cannot be in the ecliptic! Few surveys have been done at large angles away from the ecliptic, so have we got a way to discover other members of the Solar System? 
 
Bright diagonal object position – treat ccd array as 5 rows x 5 columns, each row, column element consists of 2 ccds of either horizontal or vertical alignment! Object is in 2nd row, 2nd column in the top ccd of the pair towards the bottom left of image.

Jon Jenkins, Kepler Co-Investigator, was, once more, kind enough to provide us an answer:

Ian is most likely seeing cosmic ray tracks which are the result of energetic particles whizzing through the CCD and depositing energy along the way. (I couldn’t tell from Ian’s email which direction he was counting CCD modules, although I found a bright cosmic ray track 2nd row, 2nd col from the top left, near the middle and low on the upper CCD in this pair.) We estimated a hit rate of 5 per square cm per second pre launch from counts reported by analysis of the LASCO CCDs aboard SOHO, which agrees well with the rates we’ve estimated from the dark frames we took prior to Dust Cover Ejection. The physics of our CCDs indicates that most cosmic rays deposit about 2500 electrons but some can deposit a whopping amount of charge. We identify and remove the “brightest” cosmic ray events from the data in ground-based processing. Most cosmic rays deposit too little energy for us  to detect them in or near the cores of our relatively bright target stars. The Field Of View (FOV) is tipped up 60 degrees above the ecliptic plane, so the chances of seeing solar system bodies is rather small, and Kuiper belt objects, for example, would not be bright enough to be seen as a bright streak in our images, and travel fast enough that to see them eclipsing stars in the FOV would require much shorter exposures than Kepler is capable of. The first light image pair consisted of one 6-sec integration (not including the 0.51 sec readout time) and one 65 sec integration (10 co-adds of individual 6-sec integrations with 0.51 sec readout times). During nominal science operations the CCD images are co-added for 30 minutes (a sum of 270 individual 6 sec exposures).

Cheers,
Jon

Homo Viator Manifest – Part I

What do we whitdraw from this fabled lands, from this enticing unknown islands at large?

We aim at a near return of Man, in full strength, to the Spirit of Adventure, towards a new quest, which was first dreamed, then imagined and finally sedimented in our species’ core, offering consistence, permitting no retreat, towards the next step, that must and will be, the embarking of members of the Human family, fellow creatures with the Beyond as flag, onboard a New Era of Discoveries.

 

Full document here (PDF file):

Homo Viator Manifest – Part I

Kepler opens a window on Mankind’s future…

Ah, but if even just a handful of them are orbited by planets as small as Earth, and if only a few of that handful of worlds are the right distance from their star to have liquid water… rivers, streams and seas… then when we look at that image we are looking at the destinations of the first interstellar probes – and beyond them, the first manned starships, whichever century they are built in.

Read more at Cumbrian Sky, BtC’s collaborator Stuart Atkinson’s blog.

The Ultreya Chronicles – I

btc_avatar_ruiWhere will we be 1000 years from?
Maybe here, maybe there, maybe everywhere, maybe nowhere…
Species come and go, they pop out and vanish at a same rhythm, some leaving no trace, others just a mere glimpse of their passage, what would make us, humans, different?
We have, nowadays, the possibility of creating the conditions for perpetuating our existence by diminishing the risk of extinction.
How? Doing what we have always done: Spreading.

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Kepler Mission – Mr. Danvk, you have an answer.

In the aftermath of Kepler’s first light images a question made by danvk, a BtC reader, arrived our comment box:

In the full image there are lots of white lines that are perfectly horizontal or vertical. What are these?

Natalie Batalha, Kepler Co-Investigator, gives us a solution for the enigma:

The white streaks are CCD artifacts associated with the saturation that occurs with the very brightest stars in the field.  CCDs are constructed by putting very tiny electronic circuitry on top of a wafer of silicon.  When light strikes the silicon surface, the photons knock electrons loose.  These (negatively charged) electrons are attracted to tiny electrodes in the circuitry because they have a positive voltage applied to them.  The electrodes themselves define individual pixels.  A very bright star will liberate so many electrons that they pile up and literally spill over to the adjacent pixel (electrode).  They spill in the direction of least resistance and that happens to be in the direction that the electrodes are chained together (up and down the columns in our case).  When spillover occurs, we call this “saturation.”  In the image, you see that some of the saturation bleeds are vertical while others are horizontal.  The individual ccds (the rectangles) were mosaic’d so that we could rotate the spacecraft 90 degrees each quarter (to keep the solar panels pointing at the Sun) and still have the image look the same (rotational symmetry).  If you train your eye on the gaps between the rectangles, you can see that they form a bit of a spiral pattern.  That’s the rotational symmetry pattern due to the orientation of the individual CCDs.

Kepler mission – stellar smear and a grain of salt

After yesterday’s release of Kepler’s first light images and being marvelled by the telescope’s full field of view I was here wondering how would look one of the several raw images composing that breathtaking view into a sea of stars.

And, now that we’re into the real stuff and aware that we won’t hear of an Earth-like planet until the team has full confirmation, for when, hipotetically, could we expect one of those candidates to make its first appearance? How soon can it be?

Natalie Batalha answers:

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Kepler mission – It’s full of stars!

Image credit: NASA/Ames/JPL-Caltech

Here’s what you have been waiting for, NASA Kepler’s full field of view – an expansive star-rich patch of sky in the constellations Cygnus and Lyra stretching across 100 square degrees, or the equivalent of two side-by-side dips of the Big Dipper.

And now let us stay with Jon Jenkins, Kepler’s Co-Investigator:

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