Zarya - Soviet, Russian and International Spaceflight
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Launches and Orbital Operations


Tyneside, UK
2021 Sep 17
Friday, Day 260

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Nauka and ISS

2021-076 SMA


Background

Russia's new 'Nauka' module for the ISS was launched 2021 July 21. It was planned to catch up with the International Space Station and dock with the downward-facing port of the 'Zvezda' module on July 29, replacing the 'Pirs' docking module.

Zvezda was the first added Russian module, arriving in 2000 to be attached to Zarya (launched 1998). Pirs was delivered by a Progress vehicle in 2001. The plan is to detach it and, using the engines of Progress MS-16 - its current occupant, to send it to a destructive re-entry over the southern Pacific Ocean.


Nauka Approach

The plot above shows the orbits of Nauka and the ISS as the module approaches. The points are times and heights published by Space-Track. The line for Nauka takes account of when actual orbit adjustments were made. There can be significant delay between the actual event and orbital data becoming available.

It is updated in real time so a revisit to this page will show the current situation in the Nauka mission.


Nauka Mission Chronology

July 21 - Nauka launched from Baikonur using a Proton-M rocket at 14:58:24 UTC, entered 191 x 346 km orbit at 15:08 UTC.

July 22 - Rumours spread that Nauka's main engine system had failed and it could only manoeuvre in space using its thrusters. There may have been a genuine problem, as evidenced by a change in the timeline of planned events for Nauka and Pirs. Nauka manoeuvred twice, the durations of the firings hint at use of its thruster system rather than main engines:

          1 - at 15:07 UTC - a firing for 17 seconds and Δv 1 m/s,

          2 - at 17:23 UTC - a firing for 250 seconds and Δv 14.6 m/s while at apogee resulted in orbit 224 x 347 kilometres.

July 23 - Orbit raised twice:

          1 - probably around 07:00-10:00 UTC, on the first orbit of the day that passed over a Russian ground-based
tracking station (Petropavlosk, Kamchatka), the result was 225 x 363 kilometres,

          2 - at about 19:40 UTC, raising the orbit to 238 x 370 kilometres.

July 24 - Two engine firings were made about one half orbit apart at 14:20:47 and 14:54:20 UTC to raise both perigee and apogee. Reportedly, one of Nauka's two main engines was used for both. Resulting orbit was 334 x 406 kilometres. ISS orbit was 419 x 421 km at the time.

July 25 - At around 11:00 UTC while over Russian ground stations, a test of Nauka's 'Kurs' rendezvous sytem was successful. It was rev 61, the 62nd circuit of the Earth. Following the test, a decision was confirmed for Pirs to be undocked July 26. A second, also successful, test of Kurs occurred at around 14:00 UTC.

RIA-Novosti news agency later reported there had been a problem with a sensor used to signal successful deployment of the Kurs aerial. It meant that the test was required to confirm the system was indeed working.

Hatches berween Zvezda and Pirs were closed, sealed and tested for leaks.

July 26 - Undocking of Progress MS-16/Pirs from ISS, over Mongolia near 45° north, 91° east, at 10:55:33 UTC. Retrofire at 14:01 UTC lasted 17.5 minutes, for Δv 120 m/s. It led to destructive re-entry above the southern Pacific Ocean at 14:42 UTC with any surviving fragments reaching the ocean surface at 15:51 UTC.

Video inspection of vacated ISS Zvezda docking port for any debris that might have been left after the Pirs undocking revealed no issues. A 'stand-by' EVA was accordingly cancelled.

July 27 - An orbital adjustment was made at 14:33 UTC using a single firing of Nauka's secondary thruster system while at orbital apogee. Earlier, Roscosmos had said there would be two manoeuvres but the second one does not seem to have been needed. The resulting orbit was 359 x 406 km and set up an encounter, at about 60 kilometres distance, with the ISS at around 08:00 UTC on July 29.

The zarya.info launch table entry for Nauka lists the detailed orbits.

July 28 - A minor 'trimming' orbit adjustment by Nauka was made at 13:43:07 UTC for an orbit 370 x 406 km. Roscosmos announced that docking with downward-facing Zvezda port of ISS was to be expected at 13:26 UTC. RIA-Novosti reported that Nauka had sufficient propellant reserves for a single docking attempt.

July 29 - Orbit adjustment manoeuvre(s) raised perigee to match orbit with ISS.

Nauka Docking

At the expected time of docking, ISS and Nauka were on a track across the network of Russian ground stations. Over a twenty four minute period between 13:15 and 13:37 UTC, they passed Bear Lakes (Moscow), Dzhusaly (near Baikonur), Kolpashevo, Ulan Ude and Ussuriysk.

The approach was automatically controlled by Kurs but docking occurred at 13:29:06 UTC under control of the ISS crew who took over with TORU at the five metre point. The docking probe was then retracted, and hooks and latches were driven home at 13:35 UTC.


Pirs Departure

Progress MS-16 with Pirs attached departed the ISS July 26 having been delayed three times from the original July 23.

Successful completion of Nauka's 'Kurs' test on July 25 was crucial to firming up a decision to undock.

Pirs Disposal


Nauka Engines

There was speculation that Nauka did not use its main engines for the orbit adjustments of July 23. A look at an ISS event may hold a clue.

2020 April 19, Zvezda's main engines were fired to change the ISS orbit. They fired for 58.5 seconds for a Δv of 0.97 metres per second. In round figures, sixty seconds of operation produces a change of 1 m/s.

The ISS, at 400 tonnes, has twenty times the mass of Nauka's 20 tonnes. Newton's second law of motion (F = ma) indicates that to produce the same Δv for Nauka, the engines would have fired for three seconds.

For Nauka's two orbit adjustments on June 23, the implied main engine firing durations are three seconds and 44 seconds respectively. The actual durations were 17 seconds and 250 seconds - both slightly less than six times the expected values.

In conclusion, assuming the thrust of Nauka's main engines is similar to the ones fitted to Zvezda, the orbit adjustments of June 23 probably used Nauka's lower-powered manoeuvring thrusters.

After Nauka made two engine firings on July 24 Roscosmos continued to keep its silence on what engines were being used. However Dmitry Rogozin, the organisation's head, published through his personal 'Twitter' account that one of the two main engines was used on that occasion.

On July 27, a news item from RIA Novosti confirmed that the first two orbit corrections were made using the manoeuvring thrusters rather than the main engine system.


Orbital Debris At Launch

Amateur satellite observers reported viewing Nauka and its rocket from Europe on the evening of launch. From The Netherlands, Dr Marco Langbroek imaged three accompanying objects, maybe protective covers from some of Nauka's external equipment. There could have been more but too small/faint to detect.

They would have consisted of a mixture of fabric and/or other lighweight materials with a very low mass to cross section ratio. Air drag at the less than 190 kilometre perigee would have caused rapid orbit decay and re-entry within hours making reliable orbit measurement difficult. As of July 28, Space-Track had not issued any orbit data or Catalogue IDs for these objects.

Nauka Debris

The image is reproduced with permission.


Page Date - 2021 Ju1 22
updated 2021 Jul 24 (Nauka Engine notes)
updated 2021 Jul 25 (Orbital Debris notes)
Updated in real time for new events

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