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

[Coastal Ron]

I am a bit troubled to note that the core did seem to do some maneuvering in the last 100 feet or so that indicates it was trying to land on the "X" rather than accept a landing a few meters off, as that implies the same programming regardless of land or sea landings.  Of course a landing on the "X" would be a great P.R. thing, but not a great strategy thing.  As it is, it was a little bit off, but only us space geeks even notice that, the big news for the rest of the world was it landed successfully, period.

I'm not sure you're remembering that RTLS has a horizontal dog-leg approach to the landing site, whereas the approach to an ASDS landing can be direct.  So on this landing the stage was gradually translating sideways from the initial aiming point just off shore as it decreased in altitude during it's final approach, meaning it had to zero out it's lateral velocity to zero before it touched down.

But if they have not modified the landing software to accept a much greater lateral error for land landings than for ASDS landings, then it really makes no difference WHERE it is trying to land, the "X" at the Cape, or the "X" at sea.

As you pointed out in your original post, we haven't seen a stage attempt a barge landing where everything was working correctly, so we don't what the practical accuracy is of a Falcon 9 1st stage under reasonable wind conditions - with such a large landing area, this stage may have been off too much for a barge landing.  We just don't have enough information yet, since we don't know what the programmed landing spot was.

[Avron]

On the barge there is virtually zero tolerance if it's off center. On land it can be programmed to land at X plus or minus say 100m.  That means no last second corrections needed to make the landing. I always thought rtls to land was the much easier option because of this.

we have seen amazing landing accuracy at McGregor, even with some crazy off axis landings . I don't think the barge size has much to do with hitting the X from 200 km up 

[Kabloona]

On the barge there is virtually zero tolerance if it's off center.

The leg span circle has a diameter of 60 feet. The barge is 150' wide. So the stage can land as much as 45' off center and still have all legs on deck. I'd hardly call that zero tolerance. It's a 45' tolerance, more or less.

The problems with barge landings so far have not been X-Y accuracy per se, and I'd make a friendly wager that the next barge landing attempt will be successful with an error of <25 feet off center, well within the 45' tolerance.

(Edited to correct basic math error   )

[llanitedave]

Only the Bingo will resolve this to everyone's satisfaction.

[macpacheco]

I think by far the highest risk factor for ASDS landing is the sea conditions. If SpaceX gets the authority to scrub due to too rough seas it should achieve good recovery factor (75% minimum, perhaps 95%).

Finally if ASDS landing works but the landing area is a bit too constrained, it could devise a larger barge with higher displacement, which would both improve pitching and increase landing area margins, but I don't think this will be necessary. Once FHR is operational, most landings will be RTLS, with F9R GEO missions that would require ASDS landing bumped to FHR with triple RTLS launch profile.

[Space Ghost 1962]

Launch azimuth is said to be 142.8 (once clear of land and over the Pacific).

A retro burn 100km downrange shooting between the Channel Islands would be about where a retroburn might occur, ending around due east from Ventura. Walking the IIP inland on the final burn from disposal to landing to avoid assets would put  it inbound from about 160 degrees azimuth. All this if RTLS.

It's about 200km downrange to San Nicolas Island, about right for a ballistic trajectory with just an entry burn and braking. About 240 degrees azimuth from  Hawthorne or Long Beach.

Barge anywhere along that path, depending on amount of boost back you'd want.

Its a light launch on a 1.1 not FT. You might choose RTLS given license/clearance simply because you have best odds and excess performance - not a bad choice to get a second one. Next best if you'd prepared a pad would be San Nicolas - like a barge landing, if you muffed it few would see more than you'd show, and you'd get a chance to see economics of a downrange recovery over that of a boost back. If you can't get clearance/license, then a barge landing practice close to Port Hueneme would seem your third best option.

From what I see, the biggest risk they have on landing is over control on terminal guidance. More tolerable on land landings because of fewer degrees of freedom.

[nadreck]

Once FHR is operational, most landings will be RTLS, with F9R GEO missions that would require ASDS landing bumped to FHR with triple RTLS launch profile.

I doubt very much if there will ever be a 3 core RTLS unless they build a much larger upper stage. There is no significant advantage over an F9 if you bring all 3 cores back to the launch site.

[Kabloona]

Launch azimuth is said to be 142.8 (once clear of land and over the Pacific).

A retro burn 100km downrange shooting between the Channel Islands would be about where a retroburn might occur, ending around due east from Ventura. Walking the IIP inland on the final burn from disposal to landing to avoid assets would put  it inbound from about 160 degrees azimuth. All this if RTLS.

It's about 200km downrange to San Nicolas Island, about right for a ballistic trajectory with just an entry burn and braking. About 240 degrees azimuth from  Hawthorne or Long Beach.

Barge anywhere along that path.

Here's a link to the map made by darga showing the barge location for Jason-3 as specified on the FCC transmitter permit.

It appears to be positioned to allow a booostback just west of the Channel Islands, getting as close to the islands as possible without overflying them.

https://www.google.com/maps/d/viewer?mid=zXmjsQgIEPtk.kEXviMLLYGIk

As for outbound trajectory, Newton_V implied earlier that a dogleg will be required:

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.

http://forum.nasaspaceflight.com/index.php?topic=29457.msg1393254#msg1393254

So they will be limited to an azimuth of about 155, then dogleg east.

[macpacheco]

Once FHR is operational, most landings will be RTLS, with F9R GEO missions that would require ASDS landing bumped to FHR with triple RTLS launch profile.

I doubt very much if there will ever be a 3 core RTLS unless they build a much larger upper stage. There is no significant advantage over an F9 if you bring all 3 cores back to the launch site.

How many GEO birds over 8 tons launch mass have been launched or are planned ?

F9R FT expendable performance is estimated to handle 7 tons to GEO-1800m/s.

How much more performance FH needs to offer with full reuse over F9R expendable ?

Just because FH could do 53 tons to LEO expendable, doesn't mean such a beast payload will ever exist.
Just because FH could to 21 tons to GEO expendable, doesn't mean there will ever be a GEO payload that will even use half of that.

I'm thinking about likely missions. It seems you're thinking about the whole realm of possibilities, in that arena, you're quite right that most missions would involve ASDS landing of the center stage, or even expending the center stage (or triple ADSD landing). But I think before we have 10+ tons to GEO birds, Raptor will come and make Falcon Heavy obsolete.

[nadreck]

Once FHR is operational, most landings will be RTLS, with F9R GEO missions that would require ASDS landing bumped to FHR with triple RTLS launch profile.

I doubt very much if there will ever be a 3 core RTLS unless they build a much larger upper stage. There is no significant advantage over an F9 if you bring all 3 cores back to the launch site.

I'm thinking about likely missions. It seems you're thinking about the whole realm of possibilities, in that arena, you're quite right that most missions would involve ASDS landing of the center stage, or even expending the center stage (or triple ADSD landing). But I think before we have 10+ tons to GEO birds, Raptor will come and make Falcon Heavy obsolete.

No I am saying that if you use the FT upper stage and you bring all three booster cores back to the launch site you get less payload to GTO than with F9R barging, or maybe 2t more than F9R with RTLS

[llanitedave]

Launch azimuth is said to be 142.8 (once clear of land and over the Pacific).

A retro burn 100km downrange shooting between the Channel Islands would be about where a retroburn might occur, ending around due east from Ventura. Walking the IIP inland on the final burn from disposal to landing to avoid assets would put  it inbound from about 160 degrees azimuth. All this if RTLS.

It's about 200km downrange to San Nicolas Island, about right for a ballistic trajectory with just an entry burn and braking. About 240 degrees azimuth from  Hawthorne or Long Beach.

Barge anywhere along that path, depending on amount of boost back you'd want.

Its a light launch on a 1.1 not FT. You might choose RTLS given license/clearance simply because you have best odds and excess performance - not a bad choice to get a second one. Next best if you'd prepared a pad would be San Nicolas - like a barge landing, if you muffed it few would see more than you'd show, and you'd get a chance to see economics of a downrange recovery over that of a boost back. If you can't get clearance/license, then a barge landing practice close to Port Hueneme would seem your third best option.

From what I see, the biggest risk they have on landing is over control on terminal guidance. More tolerable on land landings because of fewer degrees of freedom.

With regard to San Nicolas, if you land on the air strip there you then have to get the stage down the sea cliffs to the dock.  Looks like a pretty hairy operation, and I don't know that it's possible for something the size of a first stage.  That may have to wait until they can do a fly back.

[Jcc]

Launch azimuth is said to be 142.8 (once clear of land and over the Pacific).

A retro burn 100km downrange shooting between the Channel Islands would be about where a retroburn might occur, ending around due east from Ventura. Walking the IIP inland on the final burn from disposal to landing to avoid assets would put  it inbound from about 160 degrees azimuth. All this if RTLS.

It's about 200km downrange to San Nicolas Island, about right for a ballistic trajectory with just an entry burn and braking. About 240 degrees azimuth from  Hawthorne or Long Beach.

Barge anywhere along that path, depending on amount of boost back you'd want.

Its a light launch on a 1.1 not FT. You might choose RTLS given license/clearance simply because you have best odds and excess performance - not a bad choice to get a second one. Next best if you'd prepared a pad would be San Nicolas - like a barge landing, if you muffed it few would see more than you'd show, and you'd get a chance to see economics of a downrange recovery over that of a boost back. If you can't get clearance/license, then a barge landing practice close to Port Hueneme would seem your third best option.

From what I see, the biggest risk they have on landing is over control on terminal guidance. More tolerable on land landings because of fewer degrees of freedom.

With regard to San Nicolas, if you land on the air strip there you then have to get the stage down the sea cliffs to the dock.  Looks like a pretty hairy operation, and I don't know that it's possible for something the size of a first stage.  That may have to wait until they can do a fly back.

I don't see much point in landing at San Nicholas even if they could work out the logistics. The reason for downrange landings is to conserve fuel. They can minimize fuel use by putting the ASDS exactly where it is optimal to save fuel, instead of using an island that is feasible but not optimal.

[BrianNH]

This isn't worth posting in the update thread, but SpaceX has now updated their launch manifest to specify that Jason 3 is the next launch.  This is the first official confirmation that I am aware of, but it is what we were all expecting.

[Comga]

This isn't worth posting in the update thread, but SpaceX has now updated their launch manifest to specify that Jason 3 is the next launch.  This is the first official confirmation that I am aware of, but it is what we were all expecting.

Yeah, but it also lists Orbcomm as launching this coming Thursday.
NSF is a more reliable source than the SpaceX Manifest.  They just aren't particularly careful with it.

[rpapo]

This isn't worth posting in the update thread, but SpaceX has now updated their launch manifest to specify that Jason 3 is the next launch.  This is the first official confirmation that I am aware of, but it is what we were all expecting.

Yeah, but it also lists Orbcomm as launching this coming Thursday.
NSF is a more reliable source than the SpaceX Manifest.  They just aren't particularly careful with it.

That is a huge understatement.  They actually updated the thing for once?

[kevin-rf]

This isn't worth posting in the update thread, but SpaceX has now updated their launch manifest to specify that Jason 3 is the next launch.  This is the first official confirmation that I am aware of, but it is what we were all expecting.

Yeah, but it also lists Orbcomm as launching this coming Thursday.
NSF is a more reliable source than the SpaceX Manifest.  They just aren't particularly careful with it.

That is a huge understatement.  They actually updated the thing for once?

2016 is a leap year after all

btw. I didn't realize it, but google maps actually shows the oil rigs that Vandenberg launches are constantly doglegging around.

[Helodriver]

A visit out to the pad on 30 December showed a great number of personnel on the site working in multiple areas.

The transporter/erector was still outside the hangar, workers were applying touch ups to the spray on ablative material on the strongback.

The tent is still in place on the landing pad area. There is no indication from my sources there will be an RTLS attempt.

After finally seeing the size of the landing area at the Cape, it looks to me that the Vandenberg pad's cleared area and prepared surface will be smaller.

Gaseous venting and flow sounds were visible/audible from the LN2/LOX side of the propellant tank farm, this is a near daily occurrence there.

[cscott]

There was a cherry picker on the 303 barge in Los Angeles at last view, indicating that an ASDS landing might be in preparation.

Of course, they were working on OCISLY before the Orbcomm launch, and it turned out they were just preparing to move it from its JAX berth to a berth in Cape Canaveral.

[yg1968]

Stage 1 Drone Ship Landing FCC application has been filed:

https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69074&RequestTimeout=1000

I doubt that this Falcon 9 v1.1 first stage will ever be reused but there is some logic in trying to recover it on a barge.

[Dante80]

Barge position as per application.