Attachment response

response

SUBMISSION FOR THE RECORD submitted by SkyBridge LLC

response

2004-11-10

This document pretains to SAT-LOA-19970228-00021 for Application to Launch and Operate on a Satellite Space Stations filing.

IBFS_SATLOA1997022800021_407909

PAUL, WEISS, RIFKIND. whaRrTon 8 GARRISON LLP wasumoron. be soose—seea serrner 1. ouson RECEIVED tamceintonstenisn con NoV 1 0 2004 negediuent Fadual WM pols. M ore Meeand nov 1 9 2004 Regite um November 10, 2004 neomst arn masess ipntemamimet io. By Hand Ms. Marlene H. Dortch Secretary font 0 Federal Communications Commission 445 12th St, S.W. Washington, DC 20554 Re: Orbital Debris Mitigation; SkyBridge LL.C., Application for Authority to Launch and Operate the SkyBridge Satelite System — File Nos. SAT—LOA—19970228—00021; SAT—AMD—19970703—00058; SAT—AMD—19980630—00056; SAT—AMD—19990108—00004; SAT—AMD—20020917—00167; SAT—AMD—20040719—00135; Call Sign $2241. Dear Ms. Dortch: This leter is written on behalf of SkyBridge LL C. ("SkyBridge"),in response to a letter fom Thomas Tyez to the undersigned, dated October 1, 2004 (the "FCC Letter®)." The FCC Letter requested that SkyBridge provide certain additional details on its orbital debris mitigation plan for the SkyBridge satellite system. SkyBridge provides the requested information below. The Commission requested a statement as to whether SkyBridge has assessed and limited the probability of ts satelltes becoming a source ofdebris by collision with large debris or other functioning satelites. As noted in its application, SkyBridge has every economic incentive to ensure the robustness of its spacecrat Leter from Thomas 5. Tyez, Chief, Satellte Diviion to Jefi Olson, File Nos.SAT—LOA« 1997022s.00021; SAT—AMD—19970703—00058; SAT—AMD19980630—00086; SAT—AMD— 19990108—00004; SAT—AMD—20020917.00167; SAT—AMD20040719.00138, dared October 1, 204. Seealso Letter from Jefi H. Olson o Marlene K. Dorch,Secretuy,dated October 14, 2004File Nos.SAT—LOA—19970228:—00021, t al; Lettr from Jetiey H. Olsn to Marlene H Dortch, Secretary,dated October 21, 2004, ile Nos. SAT—LOA—19970228—00021, eral. mersorsoss

rauL. weiss. RIFKIND. WHARTON 8 CARRISON LLP Ms. Marlene H. Dortch design to prevent loss of valuable assets." SkyBridge has assessed the risk of collision and the design of the satellitesto ensure that the risks of collision with debris or operating satellites do not pose an unreasonable risk t the physical integrity and operation of is satelltes. Purthermore, as discussed below, SkyBridge plans to implement an active monitoring regime that examines the trajectories ofother satelltes and objects on an ongoing basis,so that, in the event of a collision threat, emergency mancuvers can be employed to avoid that potential collsion. In addition to protecting the SkyBridge investment, such measures will also help limit the probability thatits satelltes will become a source of debris. SkyBridge knows of no other NGSO system operating satellites sufficiently close (faking into account apogee, perigee, inclination, RAAN and stationkeeping tolerance) to the SkyBridge orbit (1469.3 km) to pose a systematic threat of collision due to overlapping orbital volumes. Noris SkyBridge aware of any such proposed NGSO system that is: (1) licensed by the Commission or any other administration; (2) the subject of a pending application before the Commission; or (3) the subject of an ITU filing and progressing toward implementation. Ifsuch a system were to be implemented, SkyBridge would, of course, coordinate its physical operations with the operator of such system to avoid any potential collision. Further, in the event of a satellite or other object passing through or near the orbit of any SkyBridge satellite, the monitoring procedures noted above will enable SkyBridge to avoid a collision. This system works as follows: Two Line Element (TLE) data from the NORAD system is obtained twice per week, and propagated one week in advance to predict possible collsion scenarios. Whenever a satellteor other object is predicted to come closer than 1.5 km from a protected satellite,an alarm is generated, so that the potentially affected SkyBridge satellite can be maneuvered out of harm‘s way as necessary. Such small maneuvers will not adversely affect the operational mission of SkyBridge or other systems. It should be noted that this approach currently is employed by the French Centre National d‘Etudes Spatiales (CNES) with regard to the Spot satellites. The Commission also requested clarification regarding the tolerance, during operational lif of the satellites, o which certain orbital parameters will be maintained. These tolerances are summarized in the following table: * SeeSAT—AMD—20020917—00167, Extibt Car$ perscrioms

rauL, weiss, rirKiND. whaRton 8 CarRISON LUP Ms. Marlene H. Dortch Orbital Parameter® Tolerance Apogce e =20 m, where a is the semi—major x ae =2 x 10%, where e is eccentricity Perigee e =20 m, where a is the semi—major axis se =2 x 103 where e is eccentricity Inclination 8 =15 x 10" deg., where i is inclination Right ascension of the an =1.5 x 10" deg., where 2 is RAAN ascending node (RAAN) Satclite phasing Sa =0.1 deg., where a, the phasing, is ttmue anomaly difference between two adjacent satellites on two adjacent planes® In practice, a is the parameter that experiences the greatest variation. When the stationkeeping constraintis nearing violation, « is corrected by a maneuver modifying the semi—major axis "a‘ See SAT—AMD—19990108—00004, at A—15—17 fodetils on theSkyBridge constelationorbial parmetes "Theapogse and perigee aides (, and I respectively)canbe converted to semi—major axis and eccentvicity(@ and a respectively),and vice vess, viathe formulas: a (R +R)2 (+ hJ2 +R e (Re RJC +R heb)Ourtary where: Ry= cathradias 6278.14km m = apogee adius = R +h, porigee mdios K. +1, In the casofhe SkyBridge constelation, hy = by 14893 k: a = 7847.49 kn; and c = 8 x 10(the eccentiity is never exactly ero in a realoritalsstem due to the carh‘selipict). ‘The toleranci thesame fr both phasing (irue anomalydiference betveen two steliteson the same plane (ame RAAN)) and relativephasing(rue anomalydiference between two adjacent sateliteson two adjacent planes(diferent RAAN)). The phasingand reativephasing fothe Skyridge constelltionare90and 67.5espectively mervcriouss

PAUL, weiss. AiFKIND, WHARTON 8 CARRISON LLP Ms. Marlene H. Dortch As the Commission noted, SkyBridge has previously indicated that SkyBridge will maintain stationkeeping to within 0.1® This tolerance refers essentiallyto the tolerance fora, the source ofthe greatest variation, as noted in the table above. More precisely,it refers to the condition (sa+A0cosi)+A +(2Nsini}" <0.1deg, where Aa = Au, +2 Ae, and Au, is the mean and long term periodic evolution of the trie anomaly, and 2 Ae is the short maximal amplitude ofthe periodic term evolution of the trie anomaly coming from the eccentricity evolution. However, as noted above, in practice the term Aa dominates the equation, and leads to the need for orbital correction. If there are any questions regarding this matter, please contact the undersigned. Respectfully submitted, Diane C. Gaylor Artorneysfor ShyBridge LLC. ces Thomas Tycz Sankar Persaud Karl Kensinger * SeeSAT—AMD—20020017—00167, ExtibitCar oerscrsass


Document Created: 2004-11-29 11:39:23
Document Modified: 2004-11-29 11:39:23
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