BLAST High Altitude Telescope Launched 26
Xandu writes "BLAST, the
Balloon-borne Large Aperture Sub-millimeter Telescope, was launched
on the 11th at 11:09 UTC from
Esrange in northern Sweden, and
is currently floating over Greenland. BLAST is a
2700kg telescope
with a 2 meter primary mirror that hangs from a 1.1 million m^3 balloon floating at an
altitude of 38km that will study the star formation history of the universe.
It will float west at nearly constant latitude for about 5 days
before the flight is terminated over northwest Canada or northern Alaska. Real
time position and
flight track is available from the NSBF.
Two of the graduate students working on the project have
photo
blogs
of the entire (8 week) prep period, including several launch photos. The
press
has
more
traditional coverage as well.
And if that isn't geeky enough to make it on Slashdot, the flight computers
run Slack."
But of course... (Score:3, Funny)
And if that isn't geeky enough to make it on Slashdot, the flight computers run Slack.
This shouldn't come as any surprise...after all, it's difficult to recover from a BSOD when your reset button is in the stratosphere...
^_^
Re:But of course... (Score:1)
On the other hand, not unlike windows, when it crashes, it chrashes... All though my crash my be related to the "# rm -R .
Re:We love you Matt! (Score:2)
Love, Mo.
Re:We love you Matt! (Score:2)
I believe you. But I want to know who did write it.
Re:We love you Matt! (Score:2)
"Eric, if you're in here, we're all going to Marty's after the movie"
Meteors (Score:1)
It would have to be in inordinately large meteor (Score:2)
If it is a multi-cell balloon, it'd probably equalize at a lower altitude. Not so good for BLASTing, but considerably better than taking all of the nice electronics for a dip in the briny at circa 700km/h about 30 seconds later.
My sister-in-law's mobile 'phone hit the contents of the family washing machine at roughly 1km/h and rapidly became... unhappy. And that wasn't even salt. (-:
Re:It would have to be in inordinately large meteo (Score:2)
It is not a multi-cell balloon. But if the meteor put a hole the size of a basket ball through the balloon, it would take days (probably many days) for it to leak enough to hit the ground. There are two valves on the top of the balloon that are used to release some of the helium
Basis for a plot? (Score:2, Funny)
Electronics mysteriously stopped working for a while, then resumed.
Does anyone else see the makings of a "B" Sci-Fi/Horror movie here?
Sometimes Balloons are good enough (Score:4, Insightful)
(1) it costs less to launch the observing platform;
(2) the structural tolerance to vibration isn't important;
(3) the instrument can be recovered and reused (after some repairing...even a soft landing can break something)...
Re:Sometimes Balloons are good enough (Score:4, Interesting)
1. is safer.
2. is cheaper.
3. has greater scientific payback.
in other news, NASA will lose all gov't funding... (Score:5, Interesting)
They should just look this up in the Bible.
Re:in other news, NASA will lose all gov't funding (Score:1)
Re:in other news, NASA will lose all gov't funding (Score:2)
1.1million m^3? (Score:1)
Duration - Why Not Longer? (Score:3, Interesting)
* Are all failure modes catastrophic?
* What is the primary failure mode? Loss of lifting gas?
* Is use of Hydrogen instead of helium an option? In carefully controlled operations, the additional risk might be worth the extra lifting capacity...
* Does H2 leak faster than helium (due to molecular size)?
* Is it difficult to create a parachute and floatation system to sheild the payload in various failure modes?
* What is the problem with just letting this thing float around until it doesn't ?
* Is battery power an issue and is the payload powered by thinfilm solar cells? Is power a limitation?
* What kind device or systems keep the orientation correct? Gyroscopes?
* If there are gyroscopes, are they a major percent of payload weight?
* What kind of ambient buffetting ocurrs at float altitude? Is there any percieved motion?
* Is the limitation of a baloon the internal-to-external pressure differential?
* What percent of the cost of the mission is the balloon, and what is the payload? Flight operations costs?
It would be cool if there was more data available on the BLAST website, but it's pretty scarce. Can someone contact them? Does anyone else know about this stuff?
Re:Duration - Why Not Longer? (Score:5, Informative)
The U.S. State Dept couldn't get overflight permissions from Russia (diplomatic issues).
> What is the primary failure mode? Loss of lifting gas?
Yes. For healthy (non leaking) balloons, this is primarily due to diurnal cycles. These are 0 pressure balloons. The gas expands and heats, and vents (to maintain 0 pressure) in the sun, but then cools contracts at night, so to avoid this, long duration flights are done above or below the arctic circle. The longest flights have been ~1 month (over Antarctica) and were terminated (Still flying well) because the McMurdo station summer season was closing.
> Is battery power an issue and is the payload powered by solar cells?
Yes (6 hrs on 4x12vx85Ah NiMH batteries) and Yes.
> What kind of ambient buffetting ocurrs at float altitude? Is there any percieved motion?
The outer frame of the gondola moves around by ~0.1 degree, with important resonances at 0.5 Hz and 0.05 Hz. The inner frame is stabilized to
> Is it difficult to create a parachute and floatation system to sheild the payload in various failure modes?
BLAST comes down on a 'standard' ~140' parachute. Take a look at Don or Gaelan's web pages linked off the story for launch pictures where you can see it. If it lands in a lake, we are very sad. If it lands in the Ocean, we are even more sad. NASA/NSBF decides when to release the gondola, so that neither will happen.
> What percent of the cost of the mission is the balloon, and what is the payload?
~20% Balloon + launch campaign costs/80% instrument and development for Long Duration experiments.
> What kind device or systems keep the orientation correct?
For Elevation: the inner frame is balanced and controlled with a torque motor.
For Azimuth, on short time scales ( > Can someone contact them? You just did.
Re:Duration - Why Not Longer? (Score:5, Informative)
> What kind device or systems keep the orientation correct? Gyroscopes?
We measure the pointing with gyroscopes for short time scales and star cameras to correct them on longer time scales, along with several other coarse sensors. We use 2 redundant sets of 3 orthogonal 1-d optical gyroscopes and 2 redundant 1-Mpix cameras behind 200 f/2 Nikon lenses. We expect to measure our pointing to less than 5 arcsec.
> If there are gyroscopes, are they a major percent of payload weight?
The two sets together weigh about 5 lbs, so less than 0.1% of the total weight.
We control the azimuth pointing with a 5-ft diameter reaction wheel, made of light-weight aluminum honeycomb with ~100 lbs of brass weights at the perimeter. The moment of inertia of the wheel is approximately 1% of that of the entire gondola. We keep the reaction wheel spinning at reasonable rates (~ 10 rpm) with a torque motor in the pivot. Elevation pointing is accomplished with a torque motor and a fluid balancing system to offset the cryogen boil-off.
We are always happy to answer questions, so ask away.
Re:Duration - Why Not Longer? (Score:2)
* Didn't see an answer about which lifting gas - H2 or He?
* Wouldn't launching from the North Pole station in summer (now, really) mean no daily temperature cycles or sunlight-heating differentials?
* Does anyone from Russia's version of the National Science Foundation or any of the Russian science bureaus read Slashdot?
* Was there something specific that caused Russia to say no to overflight rights?
* Politics aside, what was the maximum probable mission time - just another day
Re:Duration - Why Not Longer? (Score:5, Informative)
I think that Prof. Barth's text got cut off in a weird way. He's probably tired. We all are. The balloon is filled with helium.
* Wouldn't launching from the North Pole station in summer (now, really) mean no daily temperature cycles or sunlight-heating differentials?
Which North Pole station are you talking about? The secret one that no one knows about? Seriously, the problem would be transportation. How would you get the (heavy) equipment out there? Where would we land when it's time to terminate the flight? We'd like to be able to recover the entire experiment, and there is basically no plane that could, in once piece, carry a 2700kg gondola from the polar ice cap back to civilization.
There are usually 2 balloon flights a year from McMurdo. People have talked about launches from South Pole (where there is a station), but the cost of getting everything out there is way way way to expensive, when McMurdo is almost as good (or better).
* Does anyone from Russia's version of the National Science Foundation or any of the Russian science bureaus read Slashdot?
Good question. Since it didn't make the front page, only the Science page, probably not.
* Was there something specific that caused Russia to say no to overflight rights?
Nothing specific, they currently prohibit everyone but the French. It's being worked on, but it's too late for us. Next season (next year) other experiments will probably be allowed to fly all the way around.
* Politics aside, what was the maximum probable mission time - just another day or two or (if going over Russia was possible) doubling to 14 or more days?
For an LDB balloon the nominal time is 14 days, and there have been flights as long as about 30 days. Those all flew from McMurdo (Antartica), where there is no issue with flying over other countries. (14 days happens to be about the time is usually takes to circumnavigate the pole at these altitudes).
For BLAST, we're limited by the cryogens in the cryostat that houses our detectors. As configured, we get about 11 days hold time. That would double our data time time around (looks like we'll get about 5 days at float). With a few modifications, we should be able to get the hold time to 14-15 days.
* Has anyone assigned probabilities to each of the various failure modes?
Historical data indicates that a balloon operates to achieve scientific minimums 95% of the time.
prof_barth tells me that annecdotally, about 1/5 experiments get torched on landing.
* If gondola weight determines spare gas capacity determines flying time, isn't there a way to just create an elastic balloon material that doesn't need a relief valve?
Theoretically, yes. They've tried, and NASA calls it ULDB (we're LDB, that's for long duration balloon, ULDB is ultra-long duration balloon). They've only just started to test them in the last few years, and so far they have all had some kind of failure (often a 'catastophic leak'). If they get one up that doesn't leak, they expect it'll last for 90 days or so. prof_barth says apparently, back in the early 90's, some small super-pressure balloons (w/ very small payloads) managed to go over 100 days.
And our balloon doesn't have a relief valve per se, it just has vents to the bottom that are open always.
* Are the bureacrats Russian or American or someone else? (Somehow I'm confident it's not the Canadians...)
Good question. both
* If politics determines mission time regardless of the technical stuff, WHO IS WORKING ON THE POLITICS? (I know, international relations can be much more complicated than the science, but its frustrating to hear from my side, too. I like to read about the cool stuff you're doing). Who do we contact to help push this along for the next mission?
I don't know. But the
Re:Duration - Why Not Longer? (Score:2)
BLAST has now landed. It was cut down a little short of the plan, as it veered a little further north than we had hoped (and than the wind models and soundings predicted), so it was brought down on Victoria Island, NWT. There are currently people out surveying the gondola at it's landing site, and it should be recovered in the next few days. No real word on damage other than from a thousand feet up (in a plane) it looks not bad.
Just in time... (Score:1)
"Municipal officials will discuss recent proposals by Alaska Senator Ted Stevens for a national video franchise agreement, the importance of protecting public rights of way, the ability of cities to provide broadband connections for their residents and businesses, and the upcoming rewrite of the Telecommunications Act at a meeting of the National League of Cities (NLC), June 16-18, in Anchorage