SpaceX F9 / Crew Dragon : Crew-2 : 22 April 2021 - DISCUSSION

[Comga]

I believe OFT-2 will dock to Node 2 forward (IDA-2), which means Crew-1 must relocate to Node 2 zenith (IDA-3).  All 4 crew members will need to be aboard for the relocation in the event of a redocking problem forcing a return to Earth.  So it makes sense that NASA would want to schedule the relocation near the end of an increment, rather than near the beginning of one.

But...
CRS-2/SpX-21 demonstrated autonomous docking of an upgraded Dragon to Node-2 Zenith.
If OFT-2 slips, launching after Crew-1 returns leaves the forward port open for it.
That's simpler operationally than relocating the Crew-1 Resilience Dragon.
That might even favor OFT-2 being after the beginning of this particular increment.

[gongora]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

[Comga]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

OK
Why is that?
SpX-21 docked to Node 2 autonomously on its first flight while crew-critical Resiliency was docked to Node 2 Forward.
Resilience docked to Node2 forward with supervised autonomy.
Having proven autonomous docking to both ports what is gained by port swapping?

[Josh_from_Canada]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

OK
Why is that?
SpX-21 docked to Node 2 autonomously on its first flight while crew-critical Resiliency was docked to Node 2 Forward.
Resilience docked to Node2 forward with supervised autonomy.
Having proven autonomous docking to both ports what is gained by port swapping?

The Canadarm can't take cargo out of the trunk when Cargo Dragon's docked to PMA-2/IDA-2. Thus all Cargo Dragon flight will be docking to PMA-3/IDA-3.

[gemmy0I]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

OK
Why is that?
SpX-21 docked to Node 2 autonomously on its first flight while crew-critical Resiliency was docked to Node 2 Forward.
Resilience docked to Node2 forward with supervised autonomy.
Having proven autonomous docking to both ports what is gained by port swapping?

Cargo Dragons need to be at the Zenith port for the Canadarm to reach into the trunk. The trunk would be too far away from the nearest Canadarm base station if Dragon were docked to the Forward port.

If the planned exchange program between U.S. and Russian vehicles were in operation, there would be no need for an expedition Crew Dragon to ever dock at the Zenith port as there wouldn't be two Commercial Crew vehicles on station at the same time (except for tourist ships and other short-duration visits, which could be coordinated to avoid overlap with Cargo Dragons). But because Roscosmos has been dragging its feet on certifying Crew Dragon as "safe" for its cosmonauts (they don't want to be seen as automatically trusting the American certification for political reasons), each nation has to do separate overlapping crew handoffs in the meantime to avoid having their side of the station de-crewed. Hence the need for all the port juggling. Hopefully this will cease to be an issue in the near future (there has been talk of a cosmonaut exchanging a Soyuz seat with a USOS astronaut for a seat on Crew-3).

Starliner OFT-2 needs to dock at the Forward port for a different reason: the Commercial Crew program milestones only require software compatibility with the Forward port for the demo missions, and thus Starliner doesn't support the Zenth approach yet. (The same was true of Dragon which didn't support the Zenith approach until Crew-1.) That means Crew Dragon has to move to Zenith to make room for Starliner's two-week mission, then move back to Forward before the next Cargo Dragon arrives. A lot of juggling.

[cwr]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

OK
Why is that?
SpX-21 docked to Node 2 autonomously on its first flight while crew-critical Resiliency was docked to Node 2 Forward.
Resilience docked to Node2 forward with supervised autonomy.
Having proven autonomous docking to both ports what is gained by port swapping?

Cargo Dragons need to be at the Zenith port for the Canadarm to reach into the trunk. The trunk would be too far away from the nearest Canadarm base station if Dragon were docked to the Forward port.

If the planned exchange program between U.S. and Russian vehicles were in operation, there would be no need for an expedition Crew Dragon to ever dock at the Zenith port as there wouldn't be two Commercial Crew vehicles on station at the same time (except for tourist ships and other short-duration visits, which could be coordinated to avoid overlap with Cargo Dragons). But because Roscosmos has been dragging its feet on certifying Crew Dragon as "safe" for its cosmonauts (they don't want to be seen as automatically trusting the American certification for political reasons), each nation has to do separate overlapping crew handoffs in the meantime to avoid having their side of the station de-crewed. Hence the need for all the port juggling. Hopefully this will cease to be an issue in the near future (there has been talk of a cosmonaut exchanging a Soyuz seat with a USOS astronaut for a seat on Crew-3).

Starliner OFT-2 needs to dock at the Forward port for a different reason: the Commercial Crew program milestones only require software compatibility with the Forward port for the demo missions, and thus Starliner doesn't support the Zenth approach yet. (The same was true of Dragon which didn't support the Zenith approach until Crew-1.) That means Crew Dragon has to move to Zenith to make room for Starliner's two-week mission, then move back to Forward before the next Cargo Dragon arrives. A lot of juggling.

NASA's plan for commercial crew has always been for overlapping commercial crew handovers. Even when NASA and Roscosmos agree on a seat barter for crew handover, the USOS will still use overlapping crew exchange.

Carl

[russianhalo117]

Note that ROSCOSMOS will be returning to direct handover as well for its flights starting sometime this year.

[gemmy0I]

NASA's plan for commercial crew has always been for overlapping commercial crew handovers. Even when NASA and Roscosmos agree on a seat barter for crew handover, the USOS will still use overlapping crew exchange.

I wasn't aware of that, thanks. In that case there is a lot of incorrect information floating around out there, as I've often heard it stated that it was due to the present lack of seat bartering.

[SMS]

https://twitter.com/Thom_astro/status/1354336449877962752

[mandrewa]

If Crew-1 doesn't move to Zenith then Crew-2 will have to move from Zenith to Forward before SpX-22 launches.  Crew vehicles are going to have to move around for Cargo Dragons.

OK
Why is that?
SpX-21 docked to Node 2 autonomously on its first flight while crew-critical Resiliency was docked to Node 2 Forward.
Resilience docked to Node2 forward with supervised autonomy.
Having proven autonomous docking to both ports what is gained by port swapping?

Cargo Dragons need to be at the Zenith port for the Canadarm to reach into the trunk. The trunk would be too far away from the nearest Canadarm base station if Dragon were docked to the Forward port.

If the planned exchange program between U.S. and Russian vehicles were in operation, there would be no need for an expedition Crew Dragon to ever dock at the Zenith port as there wouldn't be two Commercial Crew vehicles on station at the same time (except for tourist ships and other short-duration visits, which could be coordinated to avoid overlap with Cargo Dragons). But because Roscosmos has been dragging its feet on certifying Crew Dragon as "safe" for its cosmonauts (they don't want to be seen as automatically trusting the American certification for political reasons), each nation has to do separate overlapping crew handoffs in the meantime to avoid having their side of the station de-crewed. Hence the need for all the port juggling. Hopefully this will cease to be an issue in the near future (there has been talk of a cosmonaut exchanging a Soyuz seat with a USOS astronaut for a seat on Crew-3).

Starliner OFT-2 needs to dock at the Forward port for a different reason: the Commercial Crew program milestones only require software compatibility with the Forward port for the demo missions, and thus Starliner doesn't support the Zenth approach yet. (The same was true of Dragon which didn't support the Zenith approach until Crew-1.) That means Crew Dragon has to move to Zenith to make room for Starliner's two-week mission, then move back to Forward before the next Cargo Dragon arrives. A lot of juggling.

NASA's plan for commercial crew has always been for overlapping commercial crew handovers. Even when NASA and Roscosmos agree on a seat barter for crew handover, the USOS will still use overlapping crew exchange.

Carl

Overlapping commercial crew handovers mean that every six months there will be a short period with eleven astronauts on the ISS.   And if Roscosmos does the same, ten or eleven member crews will occur every three months.  So overlapping commercial crew handovers means more research. 

But if NASA and Roscosmos agree on a seat barter this will open up the option of not doing an overlapping crew handover and given the limited number of ports on the NASA side then surely there will be circumstances where that option will be tempting.

[OnWithTheShow]

Starliner OFT-2 needs to dock at the Forward port for a different reason: the Commercial Crew program milestones only require software compatibility with the Forward port for the demo missions, and thus Starliner doesn't support the Zenth approach yet. (The same was true of Dragon which didn't support the Zenith approach until Crew-1.) That means Crew Dragon has to move to Zenith to make room for Starliner's two-week mission, then move back to Forward before the next Cargo Dragon arrives. A lot of juggling.

So this begs the question how much propellant reserve is required on commercial crew vehicles for relocations.

[gemmy0I]

Starliner OFT-2 needs to dock at the Forward port for a different reason: the Commercial Crew program milestones only require software compatibility with the Forward port for the demo missions, and thus Starliner doesn't support the Zenth approach yet. (The same was true of Dragon which didn't support the Zenith approach until Crew-1.) That means Crew Dragon has to move to Zenith to make room for Starliner's two-week mission, then move back to Forward before the next Cargo Dragon arrives. A lot of juggling.

So this begs the question how much propellant reserve is required on commercial crew vehicles for relocations.

Indeed. I suspect it's relatively small, though, considering that the vehicles have several hundred m/s of delta-v in store for a nominal mission. Dragon in particular has the advantage of being able to share delta-v between its maneuvering thrusters and abort motors, the combined propellant margins of which would be substantially oversized due to having been originally designed for propulsive landing. That should, in theory, be entirely above and beyond the baseline delta-v allotment for an ISS mission, which was budgeted into the design back when propulsive landing was still planned.

In the original propulsive landing design, there was extra delta-v on board, above and beyond that needed for on-orbit maneuvers, which could be used for either an abort or a landing, but not both, the thinking being that they'd fall back to parachutes in an abort. Now that propulsive landing isn't a thing, that extra delta-v still has to be carried for abort purposes, but upon safely reaching orbit becomes fully available for maneuvers. This is in contrast to Starliner which, for some reason, isn't designed to maneuver on-orbit with the weight of the extra abort propellant and thus needs to "dump" it by finishing orbit insertion with its own motors after being dropped off on a trajectory intentionally short of orbit by Atlas V. (That seems to be one of the reasons why it wasted so much fuel on OFT-1 when the capsule's mission timer got mixed up, because it was in an unstable orbit and had one shot to perform the critical circularization burn; that burn was performed late and thus required a lot more delta-v due to orbital mechanics not favoring the late burn.)

The bounty of delta-v on board Dragon 2 is apparently what will make possible the upcoming Space Adventures free-flying tourist mission that is supposed to raise its apogee to over 1000 km with the onboard Dracos after being dropped off in a standard low LEO by Falcon 9.

[FutureSpaceTourist]

twitter.com/thesheetztweetz/status/1354800132777267203

NASA plans to reuse a Falcon 9 first stage for the Crew-2 mission later this spring. I asked for an update from Steve Stich, NASA's program manager for commercial crew, and it sounds like they're working through the review process.

https://twitter.com/sciguyspace/status/1354800376978042880

Stich: "So far, the team has not identified any showstoppers and the Commercial Crew Program Control Board continues to review the components for flight using the standard process."

[FutureSpaceTourist]

https://twitter.com/commercial_crew/status/1355230929011281928

Launch Alert 🚀 @NASA and @SpaceX are targeting no earlier than April 20 for the launch of the second crew rotation mission with astronauts to the @Space_Station.

The Crew-2 mission will lift off from Launch Complex 39A at @NASAKennedy. Learn more: go.nasa.gov/2NRezZz

https://blogs.nasa.gov/commercialcrew/2021/01/29/nasa-spacex-to-launch-second-commercial-crew-rotation-mission-to-international-space-station/

[Rondaz]

NASA, SpaceX to Launch Second Commercial Crew Rotation Mission to International Space Station

Anna Heiney Posted on January 29, 2021

Members of the SpaceX Crew-2 mission to the International Space Station participated in training in Hawthorne, California, on Jan. 11, 2021. Pictured from left are ESA (European Space Agency) astronaut Thomas Pesquet, NASA astronauts Megan McArthur and Shane Kimbrough, and Japan Aerospace Exploration Agency (JAXA) astronaut Akihiko Hoshide. Photo Credit: SpaceX
NASA and SpaceX are targeting no earlier than Tuesday, April 20, for launch of the second crew rotation mission with astronauts on an American rocket and spacecraft from the United States to the International Space Station.

NASA’s SpaceX Crew-2 mission will launch four astronauts aboard a Crew Dragon spacecraft on a Falcon 9 rocket to the space station. It will be the first mission to fly two international partner crew members as part of the agency’s Commercial Crew Program.

NASA astronauts Shane Kimbrough and Megan McArthur will serve as spacecraft commander and pilot, respectively. Japan Aerospace Exploration Agency (JAXA) astronaut Akihiko Hoshide, and ESA (European Space Agency) astronaut Thomas Pesquet will join as mission specialists.

The mission will lift off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida. The crew is scheduled for a long-duration stay aboard the orbiting laboratory, living and working as part of what is expected to be a seven-member crew.

Crew-2 also is expected to arrive at the space station to overlap with the astronauts that flew to the station as part of the agency’s SpaceX Crew-1 mission.

Return of Crew-1 with NASA astronauts Michael Hopkins, Victor Glover and Shannon Walker, along with JAXA astronaut Soichi Noguchi, is currently scheduled for late April or early May. Crew-2 astronauts are set to return in fall 2021.

NASA and SpaceX also continue preparations for the launch of the agency’s Crew-3 mission, which currently is targeted for fall of this year.

https://blogs.nasa.gov/kennedy/2021/01/29/nasa-spacex-to-launch-second-commercial-crew-rotation-mission-to-international-space-station/

[ddspaceman]

https://twitter.com/ROBO_Tim/status/1355288576859262980

[SMS]

https://twitter.com/Thom_astro/status/1355439418518228994

[zubenelgenubi]

Cross-post:

http://www.launchphotography.com/Launch_Viewing_Guide.html

FALCON 9
<snip>The next Crew Dragon, Crew-2, carrying four astronauts to the space station, is targeted for April 20, around 5 or 6am EDT.

[SMS]

https://twitter.com/SpaceGirlLina/status/1358995671093678080

[SMS]

https://twitter.com/Commercial_Crew/status/1359209422292197377