Re: ISS orbit adjustment planned for Apr 19

From: Bob Christy via Seesat-l <seesat-l_at_satobs.org>
Date: Sun, 19 Apr 2020 09:57:21 +0100
Roscosmos reports success using Zvezda's pair of thrusters.

At approx 05:09:30 UTC they were fired for 58.5 seconds to provide Δv 0.97 m/s and lower the orbit height by 1.6 km.

The ground track in now set up for planned launch of Progress MS-14 on Apr 25, 01:51 UTC followed by a 3.3 hour flight to ISS.

Bob Christy

> On 18 Apr 2020, at 18:07, Bob Christy <bob_at_zarya.info> wrote:
> 
> Apologies... I did like everyone else, I made an assumption and read the NASA data in the wrong order.
> 
> This event is going to REDUCE the height of the ISS orbit by 2 km.
> 
> Jonathan McDowell tells me that it will use the Zvezda thrusters - nearly 20 yrs after they went into space.
> 
> Bob Christy
> 
>> On 18 Apr 2020, at 17:42, Bob Christy via Seesat-l <seesat-l_at_satobs.org> wrote:
>> 
>> This isn't a regular adjustment using Progress engines. They usually involve firing thrusters for around 4 minutes, provide Δv of about 0.5 m/s and raise ISS orbit by around 1 km.
>> 
>> The planned firing for this adjustment is about one minute, the Δv will be about 1.0 m/s and it will add 2 km to the orbit.
>> 
>> I suspect possible use of Cygnus NG-13 thrusters.
>> 
>> Bob Christy
>> 
>>>> On 17 Apr 2020, at 16:19, Jonathan McDowell via Seesat-l <seesat-l_at_satobs.org> wrote:
>>> 
>>> Collision avoidance is never planned (or known to be needed) that far (it's
>>> been in the schedule for several days already) in advance I think.
>>> This is just a regular boost.
>>> 
>>>> On Fri, 17 Apr 2020 at 06:21, Kevin Fetter via Seesat-l <seesat-l_at_satobs.org>
>>>> wrote:
>>>> 
>>>> On Apr 19, a planned change is the ISS orbit is scheduled to be done. At
>>>> first, I thought it would be a orbit boost, but then I thought maybe it
>>>> will be done for collision avoidance. as maybe something was to pass to
>>>> close to the station without the change in orbit.
>>>> 
>>>> Anything predicted to buzz the station soon.
>>>> 
>>>> Kevin
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Received on Sun Apr 19 2020 - 03:58:27 UTC

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