SpaceX Falcon 9 v1.1 - Jason 3 - SLC-4E Vandenberg - Jan 17, 2016 - DISCUSSION

[CJ]

Yes, I get an azimuth of 150 degrees.

Thanks!

I've attached a pic showing that ground track. Any RTLS would need to either dogleg (added complexity plus use more fuel) or use a reciprocal bearing. The F9 would only need to deviate east by 7 miles at touchdown to come down in downtown Lompoc, which I suspect that the range commander would prefer it not do.

On the other hand, they have an FTS for a reason, and the nominal ground track looks like it avoids overflight of anything major.

[Newton_V]

I've attached a pic showing that ground track. Any RTLS would need to either dogleg (added complexity plus use more fuel) or use a reciprocal bearing. The F9 would only need to deviate east by 7 miles at touchdown to come down in downtown Lompoc, which I suspect that the range commander would prefer it not do.

On the other hand, they have an FTS for a reason, and the nominal ground track looks like it avoids overflight of anything major.

I think your trace is a little too far east.  I don't believe an IIP trace over Santa Rosa is allowed.  The ground track is allowed (and could be over Santa Rosa, when the IIP is not), but that would be more yaw steering than needed for an inclination of 66 deg.

[Darga]

Yes, I get an azimuth of 150 degrees.

Thanks!

I've attached a pic showing that ground track. Any RTLS would need to either dogleg (added complexity plus use more fuel) or use a reciprocal bearing. The F9 would only need to deviate east by 7 miles at touchdown to come down in downtown Lompoc, which I suspect that the range commander would prefer it not do.

On the other hand, they have an FTS for a reason, and the nominal ground track looks like it avoids overflight of anything major.

Interesting that it does not align with the barge location. https://www.google.com/maps/d/edit?mid=zXmjsQgIEPtk.kYrBNGp0Rvco

[Kabloona]

Probably that barge location is to avoid overflying the islands. I think if you drew a line from where stage 1 separates downrange to back offshore of VAFB, and you wanted a track that avoided any land overflight, the track would go just west of the islands and line up with that barge spot.

[Jarnis]

Probably that barge location is to avoid overflying the islands. I think if you drew a line from where stage 1 separates downrange to back offshore of VAFB, and you wanted a track that avoided any land overflight, the track would go just west of the islands and line up with that barge spot.

So a sideways divert boostback? Since you are turning around anyway, diverting to the side seems like not a big deal.

[deruch]

TC uplink = "telecommand uplink", usually used in conjunction with "TM downlink" = "telemetry downlink".  The strange thing is the "launch vehicle flight communications are covered under a separate RFA" business.  I'm guessing that this license is for commanding the stage pre-launch (checkout) and post-recovery (safing).  For regulatory or technical reasons, communications during flight are done under a separate license.  I wonder if that could be found.

The actual flight communications are covered separately because Jason-3 isn't a commercial launch but rather an official NASA LSP launch.  So it gets its launch frequencies covered from them as opposed to having to apply to the FCC for them.  This was the same way that it happened for the DSCOVR launch, which had frequencies assigned through the USAF.  As opposed to the way that it does it for CRS missions, which while for NASA are technically commercial launches and not official Govt. launches.  You can compare this application to the others to see the difference:

FCC application for CRS-6: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=64682

FCC application for DSCOVR: https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=63921

[jacqmans]

Jason-3 prepares for launch in early August

22/06/2015

The Jason-3 ocean altimetry satellite was shipped to Vandenberg Air Force Base, California, on 17 June. The launch campaign will start with the arrival of the satellite at Vandenberg today for a launch date in early August, to be announced by NOAA in the coming days.

Once operational, Jason-3 will secure the long-term continuity of high-precision ocean altimetry measurements in support of climate monitoring, operational oceanography and seasonal forecasting.

This service, currently provided by Jason-2, provides measurements of sea surface height, wind speed at the ocean surface and sea state. Highly accurate measurements of sea surface height are vital for monitoring mean sea level in our changing climate. They also provide one essential input to the ocean forecasting models used in operational oceanography and to the coupled ocean-atmosphere models used for “seasonal forecasting”, i.e. to predict the likelihood of intense cyclonic seasons in the tropics or a mild winter in the mid latitudes.

Jason-3 is the result of an international partnership between EUMETSAT, the French Space Agency (CNES), the US National Oceanic and Atmospheric Administration (NOAA) and the US National Aeronautics and Space Administration (NASA). In addition, the European Union will fund operations of the Jason-3 satellite as a precursor to the future Copernicus Sentinel-6/Jason-CS mission and as the reference mission for calibrating Sentinel-3 altimetry observations.

EUMETSAT, CNES and NOAA will process data from Jason-3, with EUMETSAT ensuring data access for marine users in the EUMETSAT and EU Member States. Data access will be secured via the existing efficient and cost-effective multi-mission infrastructure including the EUMETCast real-time data dissemination system, Earth observation portal and archives.


http://www.copernicus.eu/news/jason-3-prepares-launch-early-august

[CJ]

Something here is really puzzling me; the launch azimuth. Specifically, that it needs to be 150 degrees for an inclination of 66 degrees, yet the range limits for Vandy appear to be 155 degrees, as near as I can tell. (and 150 would include an overflight of Santa Rosa Island, which is national park territory but does have some occupants, as I recall). 

So, what's the answer to this conundrum? One that's theoretically available is a dogleg maneuver; launch more southerly  (say, 175 degrees true) for the first 30 seconds or so, then bend a few degrees to hit 150 (which would put the ground track clear of Santa Rosa). However, I have no clue if the F9 has this capability (I think it would depend on the software in the flight computer, as I can't see any physical reason this would cause anything more than a performance hit).

So, what are we looking at? The first-ever F9 dogleg maneuver? Or a range-limit waiver? Or is there a third option?

[Newton_V]

Something here is really puzzling me; the launch azimuth. Specifically, that it needs to be 150 degrees for an inclination of 66 degrees, yet the range limits for Vandy appear to be 155 degrees, as near as I can tell. (and 150 would include an overflight of Santa Rosa Island, which is national park territory but does have some occupants, as I recall). 

So, what's the answer to this conundrum? One that's theoretically available is a dogleg maneuver; launch more southerly  (say, 175 degrees true) for the first 30 seconds or so, then bend a few degrees to hit 150 (which would put the ground track clear of Santa Rosa). However, I have no clue if the F9 has this capability (I think it would depend on the software in the flight computer, as I can't see any physical reason this would cause anything more than a performance hit).

So, what are we looking at? The first-ever F9 dogleg maneuver? Or a range-limit waiver? Or is there a third option?

175 deg is too far south.  Flying planar, while just missing Santa Rosa, puts you in an inclination close to ~70 deg inclination.  You only need to "correct" about 4 deg of inclination.   It's mainly a performance hit, but depending on when you start the yaw steering, it could increase loads (alpha-Q) on the vehicle.  The later you start the yaw steering, the bigger the performance hit, but Q will be much lower.
The ground track is never the issue.  It's the IIP trace.  For a planar ascent, they're right on top of each other until the IIP disappears (you're orbital).
IIP overflight of San Miguel is allowed.

[CJ]

Something here is really puzzling me; the launch azimuth. Specifically, that it needs to be 150 degrees for an inclination of 66 degrees, yet the range limits for Vandy appear to be 155 degrees, as near as I can tell. (and 150 would include an overflight of Santa Rosa Island, which is national park territory but does have some occupants, as I recall). 

So, what's the answer to this conundrum? One that's theoretically available is a dogleg maneuver; launch more southerly  (say, 175 degrees true) for the first 30 seconds or so, then bend a few degrees to hit 150 (which would put the ground track clear of Santa Rosa). However, I have no clue if the F9 has this capability (I think it would depend on the software in the flight computer, as I can't see any physical reason this would cause anything more than a performance hit).

So, what are we looking at? The first-ever F9 dogleg maneuver? Or a range-limit waiver? Or is there a third option?

175 deg is too far south.  Flying planar, while just missing Santa Rosa, puts you in an inclination close to ~70 deg inclination.  You only need to "correct" about 4 deg of inclination.   It's mainly a performance hit, but depending on when you start the yaw steering, it could increase loads (alpha-Q) on the vehicle.  The later you start the yaw steering, the bigger the performance hit, but Q will be much lower.
The ground track is never the issue.  It's the IIP trace.  For a planar ascent, they're right on top of each other until the IIP disappears (you're orbital).
IIP overflight of San Miguel is allowed.

Wouldn't a 4 degree plane change in a circular orbit be a significant performance hit? I don't know how to calculate that (?) but I'll take a SWAG at it; a 180 degree change would require a delta/v of twice orbital velocity, so 90 degrees might be 100% of orbital velocity, and 4 degrees is 4.444% of 90. So, *IF* I haven't massively bungled my guesswork, a 4 degree inclination change of a circular LEO orbit (velocity about 4.8 miles per second) would be  .2133 miles per second (767 mph).  Can the F9 do that plus have enough 1st stage margin for the boostback to a point just 35 miles SW of the launchpad?

As for the IIP trace (impact point if things go pear shaped) I agree, and I'll be amazed if that goes over Santa Rosa or any other landmass. There's a channel between Santa Rosa and San Miguel they could overfly, though it's only about 2 miles wide as seen from the angle of Vandenburg, which is spot on for a 155 azimuth from the SpaceX pad. Otherwise, to avoid threading the needle, they'd need to have an azimuth (assuming no change in track) of about 170. 

From what I can find online, it looks like overflights of the islands have been prohibited by the range since at least 1996, but I've found nothing definitive.

I totally agree that doing a yaw maneuver anywhere near MaxQ would be problematic.

Could they fly 155 until passing the channel (which is 47 miles downrange) and, after MaxQ, then bend the trajectory to planar? That's get around range limitations, but I have no clue if it's feasible.

 

[Newton_V]

Wouldn't a 4 degree plane change in a circular orbit be a significant performance hit? I don't know how to calculate that (?) but I'll take a SWAG at it; a 180 degree change would require a delta/v of twice orbital velocity, so 90 degrees might be 100% of orbital velocity, and 4 degrees is 4.444% of 90. So, *IF* I haven't massively bungled my guesswork, a 4 degree inclination change of a circular LEO orbit (velocity about 4.8 miles per second) would be  .2133 miles per second (767 mph).  Can the F9 do that plus have enough 1st stage margin for the boostback to a point just 35 miles SW of the launchpad?

As for the IIP trace (impact point if things go pear shaped) I agree, and I'll be amazed if that goes over Santa Rosa or any other landmass. There's a channel between Santa Rosa and San Miguel they could overfly, though it's only about 2 miles wide as seen from the angle of Vandenburg, which is spot on for a 155 azimuth from the SpaceX pad. Otherwise, to avoid threading the needle, they'd need to have an azimuth (assuming no change in track) of about 170. 

From what I can find online, it looks like overflights of the islands have been prohibited by the range since at least 1996, but I've found nothing definitive.

I totally agree that doing a yaw maneuver anywhere near MaxQ would be problematic.

Could they fly 155 until passing the channel (which is 47 miles downrange) and, after MaxQ, then bend the trajectory to planar? That's get around range limitations, but I have no clue if it's feasible.

CJ,
You replied to my post, but then again asked questions that I answered.  IIP overflight of San Miguel is allowed.  Even though IIP overflight of Santa Rosa is not allowed, it's kind of a moot point, because creating impact limit lines up near the coast of the mainland, and near the outskirts of VAFB, will be a problem anyway.
Before 2006, some further easterly flight was allowed, but since then, flight azimuths are generally limited to a ~155 deg direction.
The "plane change" is not done on orbit, it's done after max airloads when the vehicle is still flying relatively slow (couple thousand mph), but essentially out of the atmosphere.  It's a lot easier to turn your velocity vector when you're going slow.  It's all a trade-off.  If the orbit you're going to has an apogee near a node, then it might be cheaper to do the plane change (inclination) there, but then you're looking at a 2 burn mission profile with an ~ 1 hour coast, or more.

[CJ]

CJ,
You replied to my post, but then again asked questions that I answered.  IIP overflight of San Miguel is allowed.  Even though IIP overflight of Santa Rosa is not allowed, it's kind of a moot point, because creating impact limit lines up near the coast of the mainland, and near the outskirts of VAFB, will be a problem anyway.
Before 2006, some further easterly flight was allowed, but since then, flight azimuths are generally limited to a ~155 deg direction.
The "plane change" is not done on orbit, it's done after max airloads when the vehicle is still flying relatively slow (couple thousand mph), but essentially out of the atmosphere.  It's a lot easier to turn your velocity vector when you're going slow.  It's all a trade-off.  If the orbit you're going to has an apogee near a node, then it might be cheaper to do the plane change (inclination) there, but then you're looking at a 2 burn mission profile with an ~ 1 hour coast, or more.

Sorry, I have no idea how I managed it, but I did not see your last line, the one about San Miguel.

So if I'm understanding you correctly, they actually are planning on a heading change after MaxQ on this specific flight? If so, It'll be the first time a F9 has done that, as far as I know (but they've also never needed to before). However, they'll need that capability at Brownsville for many inclinations.   

I'm obsessing a bit on the initial azimuth off the pad for Jason 3, because I'm trying to choose a good vantage point to watch and take pictures from (If my plans hold, I'll be in the area on launch day). Might be Ocean Ave in Lompoc, about 4 miles from the pad, or if there's any risk of marine layer overcast (common that time of year) I might try a peak to the south, depending on azimuth. But, if the initial azimuth is less than 160, it won't affect my choices.  Timing will though; if it's a night launch (9:30 PDT last time I looked) I'm thinking of trying around Concepcion south of the base (assuming they don't close that area). 

 

[baldusi]

Something here is really puzzling me; the launch azimuth. Specifically, that it needs to be 150 degrees for an inclination of 66 degrees, yet the range limits for Vandy appear to be 155 degrees, as near as I can tell. (and 150 would include an overflight of Santa Rosa Island, which is national park territory but does have some occupants, as I recall). 

So, what's the answer to this conundrum? One that's theoretically available is a dogleg maneuver; launch more southerly  (say, 175 degrees true) for the first 30 seconds or so, then bend a few degrees to hit 150 (which would put the ground track clear of Santa Rosa). However, I have no clue if the F9 has this capability (I think it would depend on the software in the flight computer, as I can't see any physical reason this would cause anything more than a performance hit).

So, what are we looking at? The first-ever F9 dogleg maneuver? Or a range-limit waiver? Or is there a third option?

175 deg is too far south.  Flying planar, while just missing Santa Rosa, puts you in an inclination close to ~70 deg inclination.  You only need to "correct" about 4 deg of inclination.   It's mainly a performance hit, but depending on when you start the yaw steering, it could increase loads (alpha-Q) on the vehicle.  The later you start the yaw steering, the bigger the performance hit, but Q will be much lower.
The ground track is never the issue.  It's the IIP trace.  For a planar ascent, they're right on top of each other until the IIP disappears (you're orbital).
IIP overflight of San Miguel is allowed.

Wouldn't a 4 degree plane change in a circular orbit be a significant performance hit? I don't know how to calculate that (?) but I'll take a SWAG at it; a 180 degree change would require a delta/v of twice orbital velocity, so 90 degrees might be 100% of orbital velocity, and 4 degrees is 4.444% of 90. So, *IF* I haven't massively bungled my guesswork, a 4 degree inclination change of a circular LEO orbit (velocity about 4.8 miles per second) would be  .2133 miles per second (767 mph).  Can the F9 do that plus have enough 1st stage margin for the boostback to a point just 35 miles SW of the launchpad?

As for the IIP trace (impact point if things go pear shaped) I agree, and I'll be amazed if that goes over Santa Rosa or any other landmass. There's a channel between Santa Rosa and San Miguel they could overfly, though it's only about 2 miles wide as seen from the angle of Vandenburg, which is spot on for a 155 azimuth from the SpaceX pad. Otherwise, to avoid threading the needle, they'd need to have an azimuth (assuming no change in track) of about 170. 

From what I can find online, it looks like overflights of the islands have been prohibited by the range since at least 1996, but I've found nothing definitive.

I totally agree that doing a yaw maneuver anywhere near MaxQ would be problematic.

Could they fly 155 until passing the channel (which is 47 miles downrange) and, after MaxQ, then bend the trajectory to planar? That's get around range limitations, but I have no clue if it's feasible.

That's not how it is calculated. Wikipedia "Orbital Inclination change" is your friend. I've got 544m/s of delta-v deficit for a 4deg plane change at 200km circular.

[Newton_V]

So if I'm understanding you correctly, they actually are planning on a heading change after MaxQ on this specific flight? If so, It'll be the first time a F9 has done that, as far as I know (but they've also never needed to before). However, they'll need that capability at Brownsville for many inclinations.   

I don't know specifically what this flight is doing, but for all the Atlas flights (both IIAS and V) that have flow to inclinations in the low 60's, they all had similar flight azimuths, and similar turns.  Same with Delta IV (1? mission), some Delta II's, and probably a handful of Titan IVs.  I believe some missions even got to inclinations in the mid 50s.

[CJ]

That's not how it is calculated. Wikipedia "Orbital Inclination change" is your friend. I've got 544m/s of delta-v deficit for a 4deg plane change at 200km circular.

Thanks!
I was way off; 544 m/s is 1216 mph. I'll go play around with the formula in wikipedia to get a better understanding of why my SWAG was so off. 

[Kabloona]

But remember the delta V required for the "dogleg" turn would be less than that as Newton_V pointed out because it would be done at lower velocity during ascent, vs. on-orbit where orbital velocity is higher.

You can see from that orbital inclination change equation that delta V needed for plane change is directly proportional to velocity for a circular orbit, so if you're at only half orbital velocity you need only half the delta V to do the plane change.

[abaddon]

We have to assume that the Jason-3 1st stage could do a full boost-back burn if it were given regulatory approval by USAF.  I can't imagine that a dogleg maneuver as we are discussing would require nearly as much fuel as a full RTLS profile.  There should be plenty of margin to spare as they will almost certainly be attempting a barge landing instead of RTLS due to lack of said approval.

Of course, the fact that SpaceX was trying to get approval for this flight to RTLS means they believe it could execute whatever dogleg maneuver is required in addition to a full RTLS profile so...

[Kabloona]

Can we boil the above down to the following:

1. IIP overflight of San Miguel is allowed, but IIP overflight of Santa Rosa is not, so that determines easternmost IIP track. From geometry, a launch azimuth of 150 degrees would be ideal, but the above contraints mean the actual launch azimuth will be slightly more southerly.

2. As a result, some yaw steering during ascent will be required to get Jason-3 to its 66 degree inclination.

3. It's not going to be a significant performance hit.

[Joffan]

Also note, for those unfamiliar with the dynamics, that the IIP can be steered out around and beyond the islands long before the vehicle gets that far away from the launch pad. This will all happen relatively early in the flight.

[psloss]

I didn't hear a question in the CRS-7 post launch briefing about impacts to this launch...has anyone heard or seen anything?