SpaceLogistics MEV (Mission Extension Vehicle) : GEOsat servicing

[StarryKnight]

https://twitter.com/planet4589/status/1908367383242084849

On 2020 Feb 25 the Northrop Grummann MEV-1 spacecraft docked with the Intelsat 901 sat in GEO and provided it with five extra years of propulsion and power at the 27.5 West location. On Mar 31 to Apr 3 it boosted Intelsat to the GEO graveyard and has now apparently undocked

MEV provides propulsion and attitude control for the satellite it's docked to. It does not provide power.

MEV-1 will now drift to the Optus D3 satellite at 156 East longitude and dock with it. MEV will then lower D3's inclination to less than 0.05 degrees (from approx. 0.75) degrees and eventually undock so that Northrop Grumman's Mission Robotics Vehicle (MRV) can install a Mission Extension Pod (MEP) on it after the MRV and three MEPs are launched next year. MRV will then move on to service other satellites while MEP-1 will provide propulsion to Optus D3 to maintain orbit. Unlike MEVs, MEPs do not provide attitude control to its host satellite. The host satellite must provide attitude control.

[AndrewM]

https://twitter.com/s2a_systems/status/1908327472434733214 [Apr 4]

Undocked MEV-1 #44625 and INTELSAT 901 (IS-901) #26824, recorded on 2025-04-05 at 01;01:29 UTC from South America.

[StarryKnight]

Northrop Grumman press release on MEV1/IS-901 undocking. It also notes that MEV2 will remain docked to IS-10-02 for four more years.

https://news.northropgrumman.com/news/releases/northrop-grumman-achieves-first-ever-undocking-between-two-commercial-spacecraft-in-geosynchronous-orbit

[StarryKnight]

MEV-1 has reached the Optus D3 orbital slot, according to the public TLE dated yesterday. It should be in rendezvous operations now, which would put ProxOps and Docking 2-4 days away.

[starbase]

Not docked yet

https://twitter.com/s2a_systems/status/1922403507514081444

[StarryKnight]

Not docked yet

https://twitter.com/s2a_systems/status/1922403507514081444

It looks like since May 7 they've had one or two close approaches/docking attempts but had to abort for whatever reason. Each abort pushes MEV to an "orbit" around the client vehicle more than a couple of kilometers out while staying within the client's orbital slot. It can stay in that formation flying orbit as the team makes adjustments to avoid whatever caused the aborted attempt. Once they are ready it takes almost a day to spiral in to begin proximity operations (bringing MEV within the client's keep-out-sphere) and finally making another docking attempt.

[StarryKnight]

Haven't seen an official announcement, but hearing that docking was successfully completed earlier today.

[lightleviathan]

Visual confirmation as well

https://twitter.com/s2a_systems/status/1924772915091845138/photo/1

[StraumliBlight]

Haven't seen an official announcement, but hearing that docking was successfully completed earlier today.

The Special Temporary Authority to control MEV-1 while docking with Optus D3 was set to "Action Complete" yesterday.

[jbenton]

Quick question:

I take for granted that a MEV wouldn't last nearly as long in LEO as GEO on the same fuel tank (too much atmospheric drag). What about SSO? Would any modification of the design be required to extend the life of satellites 600-800km up?

I was thinking about this for two reasons: Firstly, NASA satellites Aqua, Terra and Aura are not long for this world. Secondly, I was thinking about the more complicated Restore-L/OASM-1 mission which was cancelled last year (and cost $2 billion over 8 years). This was meant to be trialed on the Landsat-7. I was wondering if the simpler MEV could be deployed instead. Anyways, much earlier in this thread, it was mentioned that Space Logistics has no plans to operate in LEO anytime soon. I don't expect that to change, but I'm curious if it would be technologically feasible to do SSO without a major redesign.  

https://spacenews.com/northrop-grumman-to-launch-new-satellite-servicing-mission-in-2024/

WASHINGTON — SpaceLogistics, a satellite-servicing firm owned by Northrop Grumman, announced Feb. 21 it [snip]
The MEV and MRV will service satellites in geosynchronous orbit. SpaceLogistics has no plans currently to provide services in low Earth orbit, although it might consider opportunities in debris removal.

“Certainly there’s a significant debris issue in low Earth orbit that one day will need to be addressed,” said Anderson. “Everything we’re doing today for satellite servicing in GEO can be directly applied to debris mitigation in low Earth orbit or to other services there, if and when customers decide to pay for those types of services.”

[Jim]

Quick question:

I take for granted that a MEV wouldn't last nearly as long in LEO as GEO on the same fuel tank (too much atmospheric drag). What about SSO? Would any modification of the design be required to extend the life of satellites 600-800km up?

I was thinking about this for two reasons: Firstly, NASA satellites Aqua, Terra and Aura are not long for this world. Secondly, I was thinking about the more complicated Restore-L/OASM-1 mission which was cancelled last year (and cost $2 billion over 8 years). This was meant to be trialed on the Landsat-7. I was wondering if the simpler MEV could be deployed instead. Anyways, much earlier in this thread, it was mentioned that Space Logistics has no plans to operate in LEO anytime soon. I don't expect that to change, but I'm curious if it would be technologically feasible to do SSO without a major redesign. 

Don't have the same interfaces as GEO comsats

[StarryKnight]

As Jim pointed out, the MEV docks to the client vehicle by inserting a probe with a barb attached into the Liquid Apogee Engine (LAE) which most GEO satellites have and few, if any LEO/SSO satellites have. (Some GEOs have a solid motor for orbit raising or are all electric propulsion and do not have an LAE. and therefore are not compatible for MEV docking).

Space Logistics Mission Robotics Vehicle (MRV) which is launching next year has robotic arms that can grab the separation ring or other client vehicle hard point. So LEO/SSO satellites could be serviced by a modified MRV. Although the final moments prior to docking/grabbing a client are autonomous, both MEV and MRV requires some ground in the loop operations to ensure the two vehicles are properly aligned and separated at the correct distance and moving relative to each other at a safe speed. This is easier in GEO, where several ground stations are in continuous contact with the client and MEV/MRV. Therefore, the control center of either the client or MEV/MRV can execute a command to quickly move away from each other if it looks like a collision is imminent.  LEO/SSO satellites are only within view of a given ground station for only a few minutes.

So the MRV modification would be to increase automation and/or add TDRSS type of connection. There would be other modifications that are related to such things increased thermal cycling due to more eclipses, changing lighting conditions...

[zubenelgenubi]

The slew rates some SSO satellites use may not be "replicable" by a MEV as-is.