NROL-76 launch

From: Ted Molczan via Seesat-l <>
Date: Mon, 1 May 2017 01:12:35 -0400
NROL-76 is scheduled for launch from Cape Canaveral on a Falcon 9 v1.2, during a two hour window that opens on 2017 May
01 at 11:00 UTC.

Based on the quoted report below, I now believe that the payload may be an imagery intelligence satellite built by Ball

"An NRO spokesperson said Sunday that a commercial company, Ball Aerospace, booked the launch with SpaceX as part of a
"delivery in orbit" contract with the NRO. Delivery in orbit typically describes an arrangement where a spacecraft
manufacturer - in this case, apparently Boulder, Colorado-based Ball Aerospace - is in charge of all satellite
preparations, the launch and in-orbit testing, before handing over control of the payload to the end user once it is
operational in space."

Ball's BCP 5000 bus seems relevant here:

"Our BCP-5000 offers our highest performance, most capable spacecraft - DigitalGlobe's choice for WorldView-1, -2 and -3
space vehicles. This powerful spacecraft accommodates next-generation optical and synthetic aperture radar
remote-sensing payloads. The BCP-5000 provides increased power in standard increments; higher agility with control
moment gyros (CMGs) - providing rapid retargeting capability with stability for the finest-spatial-resolution payloads.
The BCP-5000 is the quintessential choice for firm, fixed-priced spacecraft missions."

An SAR version would make sense in a 50-60 deg orbit. This might well be the replacement or follow-on of USA 193.

USA 193 was the payload of NROL-21. It failed shortly after it reached orbit in December 2006. If NROL-76 enters an
orbit similar to that of USA 193, the it would have approximately the following elements, assuming launch at 11:00 UTC.

USA 193 replacement                                      353 X 366 km
1 74301U          17121.59266207  .00000000  00000-0  00000-0 0    07
2 74301  58.5000 286.8357 0010000  90.2000 319.8000 15.69650000    09
Stage 2 after de-orbit burn                               59 X 365 km
1 74302U          17121.59266208  .00000000  00000-0  00000-0 0    09
2 74302  49.5000 271.4447 0232000 258.5002 159.5706 16.23000000    09

The epoch is for the time of the stage 2 de-orbit manoeuvre, which includes a plane change to align with the de-orbit
zone. The delta-V would be about 2.045 km/s, mainly due to the plane change, which I believe would be feasible because
of the large performance margin of the launch vehicle. If NROL-76 is built on the BCP-5000 bus, then its mass may be
similar to that of the Worldview satellites, about 2,800 kg. The following estimate shows that this is a fraction of the
performance of the Falcon 9 to a USA 193 orbit:

Launch Vehicle:   	Falcon 9 v1.2 (land recovery) w/standard fairing
Launch Site:   	Cape Canaveral / KSC
Destination Orbit:  	353 x 366 km, 58.5 deg
Estimated Payload:   	10927 kg
95% Confidence Interval:   	9515 - 12495 kg
Note: Caution: limited technical data available
Note: Possible dogleg ascent - performance impact estimated

As an alternative to a USA 193 orbit, I offer elements of a 50 deg, 300 km orbit.

Payload                                                  300 X 306 km
1 74200U          17121.46250000  .00000000  00000-0  00000-0 0    05
2 74200  50.0000 279.9856 0005000 177.0000 220.5000 15.90000000    00

Ted Molczan

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Received on Mon May 01 2017 - 00:13:47 UTC

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