Other programs we just never think about include NOAA state of the art weather from which all "local weather" is possible, free and open air navigation charts, and free air traffic control. Think about how, scattered across the entire continental USA, there are a dense network of radio towers broadcasting homing signals so that any aircraft can navigate safely without subscription or cost.
And then of course we have GPS.
It's just unbelievable the things we've built and essentially given away for the benefit of humanity. Apolitically, I look forward to an era where we can do that again (without living on borrowed time, if possible).
Clearly we do a lot more commercial space at this point but the lineage is there.
> The final steps included carefully lowering the satellite's orbit to decrease the risk of collisions and ensuring that all energy sources, such as fuel and batteries, are depleted to prevent the satellite from accidentally turning back on or creating debris. As Landsat 7 begins this decommissioned phase, it will drift silently in orbit for about 55 years before reentering Earth’s atmosphere.
It'd take a very significant and expensive amount of fuel to "just lower" the orbit! From its 700 km orbit, it'd cost (by my estimate) roughly 300 m/s, or on the order of 10% of entire satellite mass, to perform this lowering burn.
It's not at all standard practice to deliberately dispose of satellites this way (SpaceX is a major outlier), and wasn't even on the radar in the 1990's, when this satellite was being built.
(Here's an anchoring point: the projected cost for the propulsion to "just" deorbit the International Space Station, at the end of its operating life, is $1.5 billion [0]).
[0] https://spacepolicyonline.com/news/nasa-iss-deorbit-vehicle-...
That's under 2% of the total cost, that's not too much, if you compare it to the rest of the TCO, and not how beneficial would it be.
Also, repeated dockings and undockings (as you assemble the mass driver and then use it) will ruin any microgravity experiments you might want to run, so you can't really combine "base station for deep space exploration" and "science lab" missions, you really need the station to be focused on one or the other.
1: The main problem ISS has is political, not technological. By design you need the US and Russia to cooperate to keep it operating, and that made a lot of sense in the 1990s, and has fallen apart over the past decade.
2: Orbital plane changes- to move ISS to the right orbit for a specific launch site- are hideously expensive in LEO. GEO satellites often find it cheaper to raise their apogee out to near the moon, make the necessary plane change way up high, and then drop the apogee again when they get to perigee, rather than make the plane changes in LEO. (ISS can't do that.)
tbf it is now a standard practice (quite literally: it's part of ISO24113) for satellites in LEO to lower the orbit to allow reentry via natural orbital decay within 5 years or less (recently reduced from 25 years or less). Your average CubeSat launched into the lower reaches achieves this naturally through atmospheric drag without propulsion, but anyone sticking their satellite at 700km needs propulsion and sufficient total impulse to be able to conduct a deorbiting mission at end of life.
But yeah, certainly wasn't in the 1990s when congestion of LEO wasn't a consideration
How wrong I was; what this now greybeard wouldn’t give to rummage through that lab again.
RIP #7.
gnabgib•1d ago