SpaceX Falcon 9 : NASA IXPE : KSC LC-39A : 9 December 2021 (0600 UTC)

[Steven Pietrobon]

In nominal orbit. Upcoming events.

00:28:51    2nd stage engine starts
00:29:51    2nd stage engine cutoff (SECO-2)
00:33:22    IXPE deploys

[Steven Pietrobon]

One minute to second ignition.

[Comga]

It would be really neat if SpaceX had a third data point displayed for the instantaneous value of the orbit inclination.
This will be "the mother of all plane change burns."
Here we go!

edit:  The velocity is DECREASING as the second stage burn continues!
Nominal!

[Steven Pietrobon]

Ignition!

[Steven Pietrobon]

Cutoff. Nominal orbit insertion.

[Steven Pietrobon]

Stage views.

[Steven Pietrobon]

One minute to separation.

[Steven Pietrobon]

Separation!

[Steven Pietrobon]

End of SpaceX coverage.

Congratulations to SpaceX and NASA for the successful launch!

[Lars-J]

It would be really neat if SpaceX had a third data point displayed for the instantaneous value of the orbit inclination.
This will be "the mother of all plane change burns."
Here we go!

edit:  The velocity is DECREASING as the second stage burn continues!
Nominal!

Yes the velocity would be decreasing at the start of the burn as it was slightly retrograde at first. The burn was a probably a relatively fixed direction (to cancel out startup transients) so midway through the burn it would start adding more velocity again.

As for the direction of the burn, the inclination before the burn was 28 degrees. 180-28 = 152 degrees. Divide by two and you get 76 degrees north for the direction of the burn.

(Close to it anyway, the burn also circularities the orbit so it might be a few degrees off)

EDIT: here is a flightclub.io tweet about this mission before the flight:

https://twitter.com/flightclubio/status/1468637148438007808?s=21

[scr00chy]

Launch photos have been uploaded to NASA's Flickr.

[RotoSequence]

A little late to ask to be sure, but out of curiosity, what kept IXPE from flying on Vega?

[Star One]

NASA’s archived launch coverage:

[smoliarm]

A little late to ask to be sure, but out of curiosity, what kept IXPE from flying on Vega?

May be, 0° inclination of the deployment orbit.
(and of course high price)

[jacqmans]

[jacqmans]

[jacqmans]

December 09, 2021
RELEASE 21-168

NASA Launches New Mission to Explore Universe’s Most Dramatic Objects

NASA’s Imaging X-ray Polarimetry Explorer (IXPE) mission launched at 1 a.m. EST Thursday on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida.

A joint effort with the Italian Space Agency, the IXPE observatory is NASA’s first mission dedicated to measuring the polarization of X-rays from the most extreme and mysterious objects in the universe – supernova remnants, supermassive black holes, and dozens of other high-energy objects.

“IXPE represents another extraordinary first,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Together with our partners in Italy and around the world, we’ve added a new space observatory to our fleet that will shape our understanding of the universe for years to come. Each NASA spacecraft is carefully chosen to target brand new observations enabling new science, and IXPE is going to show us  the violent universe around us – such as exploding stars and the black holes at the center of galaxies – in ways we’ve never been able to see it.”

The rocket performed as expected, with spacecraft separation taking place 33 minutes into flight. Approximately one minute later, the spacecraft unfurled its solar arrays. IXPE entered its orbit around Earth’s equator at an altitude of approximately 372 miles (600 kilometers). About 40 minutes after launch, mission operators received the first spacecraft telemetry data.

“It is an indescribable feeling to see something you’ve worked on for decades become real and launch into space,” said Martin Weisskopf, IXPE’s principal investigator at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Weisskopf came up with the idea for the spacecraft and has conducted seminal experiments in X-ray astronomy since the 1970s. “This is just the beginning for IXPE. We have much work ahead. But tonight, we celebrate!”

IXPE carries three state-of-the-art space telescopes with special polarization-sensitive detectors. Polarization is a property of light that holds clues to the environment from which the light originates. The new mission builds on and complements the scientific discoveries of other telescopes, including the Chandra X-ray Observatory, NASA’s flagship X-ray telescope. First light operations are scheduled to begin in January.

NASA Marshall manages the IXPE mission for the agency’s Science Mission Directorate as a project of the NASA’s Explorers Program. IXPE is an international collaboration between NASA, the Italian Space Agency, along with partners and providers in 12 other countries. Marshall built the three X-ray telescopes. The Italian Space Agency contributed IXPE’s polarization detectors. Ball Aerospace in Broomfield, Colorado, provided the spacecraft and manages spacecraft operations at the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the Explorers Program.

For more information about the IXPE mission, visit:

https://www.nasa.gov/ixpe

[Rondaz]

IXPE Teams Communicating with NASA Spacecraft

James Cawley Posted on December 9, 2021

We have signal acquisition, meaning teams are now communicating with NASA’s Imaging X-Ray Polarimetry Explorer (IXPE) spacecraft, as it embarks on its two-year journey to study changes in the polarization of X-ray light through some of the universe’s most extreme sources, including black holes, dead stars known as pulsars, and more.

“Everything has gone smoothly; we just crossed over Africa and acquired signal of the spacecraft,” said NASA Senior Launch Director Omar Baez. “They’ll start exposing the solar rays and doing their deployments, so you can’t ask for any better than that.”

https://blogs.nasa.gov/ixpe/2021/12/09/ixpe-teams-communicating-with-nasa-spacecraft/

[Rondaz]

NASA’s IXPE Journeys to Explore the Universe

James Cawley Posted on December 9, 2021

NASA’s Imaging X-Ray Polarimetry Explorer (IXPE) mission launched at 1 a.m. EST Thursday on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida.

A joint effort with the Italian Space Agency, the IXPE observatory is NASA’s first mission dedicated to measuring the polarization of X-rays from the most extreme and mysterious objects in the universe – supernova remnants, supermassive black holes, and dozens of other high-energy objects.

https://blogs.nasa.gov/kennedy/2021/12/09/nasas-ixpe-journeys-to-explore-the-universe/

[OneSpeed]

Here is some analysis of the IXPE web-casts.

1. The first plot compares the booster profiles for IXPE and Starlink L9. Most features were similar, and in particular, both MECOs were at an altitude of 63.9km, which is typical for Starlink missions.
2. From the IXPE Mission Control Audio web-cast, there was no visible inclination change during ascent.
3. The third plot appears to show that the second S2 burn, which combined a 28.5° plane change and circularisation, caused an overall reduction in velocity, which is counter intuitive to say the least.

Indicated inertial velocity at the start of the burn is 25,474 km/h or 7076 m/s, and at shutdown it is 25,377 km/h or 7038 m/s, a reduction of 38 m/s.

Also, due to the burn occurring at a yaw angle averaging some 88.5°, the inertial acceleration starts negative, and only goes positive in the last third of the burn, peaking at less than 1g. The true acceleration of the stage would have been far higher, perhaps peaking at around 8g, the limit for IXPE.

However, it is important to remember that SpaceX webcasts display inertial velocity (velocity relative to the launch site), not  orbital velocity (velocity ignoring the rotation of the Earth).
 
At an altitude of 600km, and an inclination of 28.5°, the difference between inertial and orbital velocity is about 467 m/s, and once the plane change is complete, at 0° inclination, the difference increases to some 531m/s. So, although the displayed inertial velocity has reduced, the orbital velocity has actually increased slightly, circularising the orbit.