Old satellite teaching new lessons

SCHRIEVER AIR FORCE BASE, Colo. (AFNS) — Since Jan. 13, the 2nd Space Oper­a­tions Squadron here has been busy dis­pos­ing of an old and trust­ed satel­lite.

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GPS Block IIA satel­lite over the earth. (Cour­tesy graph­ic)
Click to enlarge

Squadron mem­bers could soon refer to the vehi­cle, known as SVN-30, as the satel­lite that keeps on giv­ing because crews con­tin­ues to gar­ner invalu­able infor­ma­tion con­cern­ing how Glob­al Posi­tion­ing Sys­tem Block IIA satel­lites behave as they degrade.

“We still have 12 GPS Block IIA vehi­cles on orbit,” said Lt. Col. Dean Holthaus, the 2nd SOPS direc­tor of oper­a­tions. “In addi­tion to the nor­mal end-of-life test and dis­pos­al pro­ce­dures, we’re con­duct­ing some tests (that) will help char­ac­ter­ize how the oth­er Block IIAs will behave with regard to their sen­sors, atti­tude con­trol, etc., dur­ing future dis­pos­al oper­a­tions.”

The Air Force launched SVN-30 dur­ing Sep­tem­ber 1996 and the vehi­cle began pro­vid­ing posi­tion, nav­i­ga­tion and tim­ing data for GPS users world­wide the very next month. Design­ers placed four atom­ic fre­quen­cy stan­dards, or clocks, on the satel­lite dur­ing con­struc­tion and it took near­ly 16 years for all four to degrade beyond their use­ful­ness. Oper­a­tions crews began notic­ing that SVN-30’s final clock was expe­ri­enc­ing trou­ble dur­ing May 2011, so 2nd SOPS crews res­ur­rect­ed a resid­ual satel­lite, SVN-35, to replace it in the GPS archi­tec­ture.

That’s when the satel­lite that keeps on giv­ing leapt back into ser­vice.

“We’ve known for some time that SVN-30 was going to present itself as the per­fect test bed,” said Capt. Jayson Ander­sen, the 2nd SOPS assis­tant flight com­man­der, GPS Mis­sion Analy­sis. “Its nav­i­ga­tion pay­load has degrad­ed to the point where it can’t sup­port posi­tion, nav­i­ga­tion and tim­ing mis­sions any­more, but its bus com­po­nents are still oper­at­ing on the pri­ma­ry side and there is plen­ty of fuel onboard. We have an incred­i­ble oppor­tu­ni­ty to gain some under­stand­ing and knowl­edge about how Block IIAs behave at the end of their oper­a­tional lives.”

More than 50 per­son­nel, includ­ing 2nd SOPS and 19th Space Oper­a­tions Squadron oper­a­tors and orbital ana­lysts, will coor­di­nate with Boe­ing and Aero­space con­trac­tors to test the satel­lite before its dis­pos­al lat­er this month.

“The major ben­e­fit for us is that the infor­ma­tion we gain from test­ing will dri­ve down risk in future dis­pos­al oper­a­tions,” Holthaus said. “We know if any­thing falls out­side the norm dur­ing future oper­a­tions, we’ll have quan­tifi­able data from SVN-30’s dis­pos­al for use in a sce­nario where we can’t dis­pose of a vehi­cle in the stan­dard fash­ion.”

Ander­sen con­tends that the 2nd SOPS is show­ing for­ward think­ing by try­ing to pro­tect high-val­ue GPS slots, which could be com­pro­mised if a satel­lite were to become inop­er­a­ble in place.

“We may not dis­pose of anoth­er vehi­cle for sev­er­al years,” he said. “But, when we are forced to dis­pose of it, we want to go into it with high con­fi­dence so that we have the low­est risk dis­pos­al pos­si­ble. We want to be able to vacate that slot and bring in a new vehi­cle.”

Final shut­down of SVN-30 will occur at the lat­er stages of the oper­a­tion, when crews will com­mand the vehi­cle to fire its thrusters, push­ing it out and up to a high­er orbit, deplete the vehi­cle of its remain­ing fuel, dis­charge all bat­ter­ies and open all valves. Teleme­try shut­down and final con­tact with earth is planned for Jan. 27.

In addi­tion to tak­ing safe­ty pre­cau­tions to ensure a mishap free tran­si­tion, the 2nd SOPS will also coor­di­nate with exter­nal orga­ni­za­tions, such as the Joint Space Oper­a­tions Cen­ter, to pro­vide pre­dict­ed burn vec­tors and post-burn vec­tors so crews can con­duct col­li­sion avoid­ance oper­a­tions with oth­er vehi­cles on orbit.

“I am proud of our team for their inno­va­tion and for­ward think­ing in this regard,” said Lt. Col. Jen­nifer Grant, the 2nd SOPS com­man­der. “We are con­stant­ly try­ing to find ways to uti­lize every satel­lite on orbit to the best of our abil­i­ty. This end-of-life test­ing will pay div­i­dends in plan­ning for future dis­pos­al, or con­tin­gency oper­a­tions for future dis­pos­al oper­a­tions.”

Source:
U.S. Air Force