Author Topic: LIVE: IBEX - Pegasus-XL - October 19, 2008  (Read 53806 times)

Offline William Graham

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #200 on: 10/19/2008 09:44 PM »
What's the latest.  Is the Spacecraft OK.  Reading between the lines I don't feel everything went as expected.

---  CHAS

I would hardly consider a delay of a few minutes in establishing communications to be a sign of a launch failure.

Offline HIPAR

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #201 on: 10/19/2008 09:57 PM »
You're probably correct but:

a) There didn't appear to be the jubilation usually associated with a perfect mission

b) They couldn't retrieve the separation data at Hawaii tracking site

c) Although satellite relayed telemetry was being received, at the time I inquired, there was no conformation of receipt of signals at the Ascension ground station and that was supposed to have happened.

---  CHAS

Offline Ford Mustang

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #202 on: 10/19/2008 10:06 PM »
Thanks to Stephan - there's a launch video clip on the free video section:
http://forum.nasaspaceflight.com/index.php?topic=14685.0


Great work by everyone with the coverage, especially via the dodgy webcast.

And I've added a 7 minute clip, which spans from T-10 seconds to LOS, then picks it back up at confirmation of spacecraft sep.
« Last Edit: 10/19/2008 10:07 PM by Ford Mustang »

Offline Chris Bergin

Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #203 on: 10/20/2008 12:37 AM »
Oct. 19, 2008

Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@nasa.gov

Nancy Neal Jones
Goddard Space Flight Center, Md.
301-286-0039
nancy.n.jones@nasa.gov
RELEASE: 08-262

NASA LAUNCHES IBEX MISSION TO OUTER SOLAR SYSTEM

GREENBELT, Md. -- NASA's Interstellar Boundary Explorer mission, or
IBEX, successfully launched from the Kwajalein Atoll in the Pacific
Ocean at 1:47 p.m. EDT, Sunday. IBEX will be the first spacecraft to
image and map dynamic interactions taking place in the outer solar
system.

The spacecraft separated from the third stage of its Pegasus launch
vehicle at 1:53 p.m. and immediately began powering up components
necessary to control onboard systems. The operations team is
continuing to check out spacecraft subsystems.

"After a 45-day orbit raising and spacecraft checkout period, the
spacecraft will start its exciting science mission," said IBEX
mission manager Greg Frazier of NASA's Goddard Space Flight Center in
Greenbelt, Md.

Just as an impressionist artist makes an image from countless tiny
strokes of paint, IBEX will build an image of the outer boundary of
the solar system from impacts on the spacecraft by high-speed
particles called energetic neutral atoms. These particles are created
in the boundary region when the 1-million mph solar wind blows out in
all directions from the sun and plows into the gas of interstellar
space. This region is important to study because it shields many of
the dangerous cosmic rays that would flood the space around Earth.

"No one has seen an image of the interaction at the edge of our solar
system where the solar wind collides with interstellar space," said
IBEX Principal Investigator David McComas of the Southwest Research
Institute in San Antonio. "We know we're going to be surprised. It's
a little like getting the first weather satellite images. Prior to
that, you had to infer the global weather patterns from a limited
number of local weather stations. But with the weather satellite
images, you could see the hurricanes forming and the fronts
developing and moving across the country."

IBEX is the latest in NASA's series of low-cost, rapidly developed
Small Explorers spacecraft. The Southwest Research Institute
developed the IBEX mission with a team of national and international
partners. Goddard manages the Explorers Program for the Science
Mission Directorate in Washington.

For more information about the IBEX mission, visit:



http://www.nasa.gov/ibex


Offline antonioe

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #204 on: 10/20/2008 01:07 AM »
Launch half of antonioe breathing again - spacecraft half still holding breath

Well congratulations to both sides, seems both IBEX and Pegasus did a great job.
Thanks; everything looks fine, but, remember, the fat lady doesn't sing until all the telemetry is analyzed...  I've been through FOURTY (40!) Pegasus launches and I STILL get butterflies until I see those plots... this one looks good, though.

Let's not forget the spacecraft, though... we now have TWO beyond the GEO belt!... let's hope it does the entire mission, although I never understood the science that allows you to map the HELIOsphere boundary from just outside the GEOsphere boundary... can anybody explain that to me?
« Last Edit: 10/20/2008 01:08 AM by antonioe »
ARS LONGA, VITA BREVIS...

Online Ronsmytheiii

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #205 on: 10/20/2008 01:31 AM »
Let's not forget the spacecraft, though... we now have TWO beyond the GEO belt!... let's hope it does the entire mission, although I never understood the science that allows you to map the HELIOsphere boundary from just outside the GEOsphere boundary... can anybody explain that to me?

this person from slashdot seems to offer a partial definition:

Quote

The probe is not going to the edge of the solar system. This is a remote sensing mission. The instruments measure the Energetic Neutral Atoms (ENAs) created through charge exchange at the boundary of the heliosphere and the interstellar medium. Its a cool/novel way to get data without the crazy cost of going to the edge of the solar system.

Amazingly it takes 6 months to make one image (one half an orbit of Earth around the sun)

http://science.slashdot.org/comments.pl?sid=1000661
"Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace." - Robert Goddard

Offline jcm

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #206 on: 10/20/2008 03:18 AM »
Launch half of antonioe breathing again - spacecraft half still holding breath

Well congratulations to both sides, seems both IBEX and Pegasus did a great job.
Thanks; everything looks fine, but, remember, the fat lady doesn't sing until all the telemetry is analyzed...  I've been through FOURTY (40!) Pegasus launches and I STILL get butterflies until I see those plots... this one looks good, though.

Let's not forget the spacecraft, though... we now have TWO beyond the GEO belt!... let's hope it does the entire mission, although I never understood the science that allows you to map the HELIOsphere boundary from just outside the GEOsphere boundary... can anybody explain that to me?


Well, we can map external galaxies by using HST, which is in LEO... because light travels in straight lines, so if you measure the direction the light rays are coming from (that's what a camera is for) you can map the shiny thing making the light rays.

What was realized more recently is that you can do the same trick with  neutral atoms, which also travel in straight lines. (ions and electrons are no good, because magnetic fields bend their trajectories into loops and you lose track of what direction they came from). Shock fronts can accelerate neutral atoms to high speeds. An ENA camera can measure the direction and speed
for the incoming neutral atoms (the speed is analogous to the color of a light photon).

So, it turns out that in a certain speed range (think of it as a certain band of ENA colors), the shiniest, brightest thing around is the heliosphere boundary. And, the denser parts of the boundary are brighter than the less dense parts. So by scanning your ENA camera around the sky, you can see which directions correspond to brighter and denser heliosphere boundary.
The only snag is that you need the sky to be 'dark', i.e. not swamped with neutral atoms going to and fro that have nothing to do with the heliosphere. That's a problem in LEO, where there's still some thin neutral Earth atmosphere, but not at IBEX's apogee. Hence the choice of IBEX orbit.

Caveat: I am not a heliospheric physicist --  extragalactic sources are my speciality. But I think that's roughly the story.
 - Jonathan
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Jonathan McDowell
http://planet4589.org

Offline antonioe

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #207 on: 10/20/2008 03:52 AM »
So, it turns out that in a certain speed range (think of it as a certain band of ENA colors), the shiniest, brightest thing around is the heliosphere boundary. And, the denser parts of the boundary are brighter than the less dense parts. So by scanning your ENA camera around the sky, you can see which directions correspond to brighter and denser heliosphere boundary.
The only snag is that you need the sky to be 'dark', i.e. not swamped with neutral atoms going to and fro that have nothing to do with the heliosphere. That's a problem in LEO, where there's still some thin neutral Earth atmosphere, but not at IBEX's apogee. Hence the choice of IBEX orbit.

Thanks, Jonathan, very enlightening.

Quote
Caveat: I am not a heliospheric physicist --  extragalactic sources are my speciality.

Oh, well, everybody knows that extragalactic astrophysicists have extraordinarily broad insights into nearly everything...!
ARS LONGA, VITA BREVIS...

Offline Paul Howard

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #208 on: 10/20/2008 04:02 AM »
Nice to see Pegasus back in action after all the hype about SpaceX. Clever reference in Chris' article about Pegasus being "the" first.

Makes a note to use the "I'm a extragalactic astrophysicist" the next time I come across an interested lady in a bar. I reckon that'd work well ;)
« Last Edit: 10/20/2008 04:03 AM by Paul Howard »

Offline jcm

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #209 on: 10/20/2008 12:05 PM »

Makes a note to use the "I'm a extragalactic astrophysicist" the next time I come across an interested lady in a bar. I reckon that'd work well ;)

No comment.....  ;-)

SpaceTrack is now giving the Peg third stage and the adapter cone in
210 x 413 km x 11.0 deg orbits. No data yet on IBEX and the Star 27H, and there may not be - Stratcom isn't set up for tracking cislunar stuff. Antonio, any info your side on the actual orbit achieved?
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Offline edkyle99

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #210 on: 10/20/2008 02:24 PM »

SpaceTrack is now giving the Peg third stage and the adapter cone in
210 x 413 km x 11.0 deg orbits.

One NASA official said something about Pegasus having flown at bit "hotter" than expected.  One report said that the expected initial orbit was supposed to be 202 km circular.  Perhaps this explains the difficulty with initial telemetry tracking efforts (esp. via. TDRS)?

I believe this was the heaviest-ever Pegasus payload.  Perhaps Pegasus has a bit more capability than cataloged.  ;)

 - Ed Kyle
« Last Edit: 10/20/2008 02:33 PM by edkyle99 »

Offline antonioe

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #211 on: 10/21/2008 04:07 PM »
Yes indeed; Pegasus was a bit hotter than expected and the spacecraft's Star 27 a bit under, so both canceled out and the spacecraft is "right on the money".   Communications were poor yesterday with the NASA GN (Santiago) but we had good communications overnight as we were back on USN stations, and acquisition was performed using estimated orbital elements, not by searching!!!

All hardware and software remains nominal at this time.  S/C despin (60 rpm to 22 rpm) was successfully performed late last night.  Radial thruster performance appeared nominal (including catbed behavior and valve soak back).  Checkout (brief test burn) of the two 22N axial thrusters is planned for Tuesday afternoon in preparation for the first perigee raising burn at apogee. The actual burn is scheduled for approximately 11pm local time Tuesday night.  Orbit raising maneuvers will continue over the next week or so until we achieve our final 7000km x 50 Re orbit
ARS LONGA, VITA BREVIS...

Offline synchrotron

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #212 on: 10/21/2008 05:51 PM »
Radial thruster performance appeared nominal (including catbed behavior and valve soak back).

Erm.  Probably a dumb question.  Nominal valve soak back concerns feed temperatures?  And how do you measure it to know that it's nominal?

Offline Jim

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #213 on: 10/21/2008 06:04 PM »
thermocouples or thermosisters I believe

Offline antonioe

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #214 on: 10/21/2008 07:22 PM »
Perhaps Pegasus has a bit more capability than cataloged.  ;)

 - Ed Kyle

Actually, this mission - like some but not all we fly - benefited from a "gimme the highest non-injection-apse you can" guidance strategy.

The launch vehicle injection orbit apogee becomes the initial perigee of the IBEX orbit, with the spacecraft's propulsion system taking care of raising this perigee to the desired 7,000 km (not very costly, since the apogee is 35 Earth Radii!!!).  The higher the Pegasus apogee, the lower the spacecraft's fuel needed to raise its perigee... everybody happy!

In these kinds of flights we do NOT manage energy (which needs an energy reserve) and we get all we can get.  Typical velocity reserves for an energy-managed flight add up to about 150 f/s (50 m/s).  Notice it takes 61 m/s of extra velocity at injection to increase the apogee from 202 km to 413 km!!!

It computes.
« Last Edit: 10/21/2008 07:25 PM by antonioe »
ARS LONGA, VITA BREVIS...

Offline jcm

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Re: LIVE: IBEX - Pegasus-XL - October 19, 2008
« Reply #215 on: 10/22/2008 04:12 AM »
IBEX orbit now reported by SpaceTrack as  219 x 250281 km x 11.0 deg
   - Jonathan
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