Comment by tarice | Hacker News Reader

Comment by tarice | Hacker News Reader

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A orbit raising maneuver was always necessary to get the satellite to its target. Relevant sections:

> "Orbcomm had planned on reaching an altitude of 466 miles above Earth..."

> "Due to the engine shutdown, the Falcon 9 used slightly more fuel and oxygen to reach Dragon's intended 202 mile- (325-km) high orbit. Over the next 2.5 days, Dragon flew itself to the station's orbit 250 miles above Earth. It reached the $100 billion outpost, a project of 15 countries, on Wednesday."

Initial Dragon Orbit: 202 miles above Earth

ISS: 250 miles above Earth

Desired Satellite Location: 466 miles above Earth

There was only a 95% chance of the rocket reaching the location 466 miles above Earth (due to the reduced fuel reserves), so they didn't perform the burn, because NASA's contract with them forbade it (had to be >=99% chance of success).

Right. They were hoping the F9 upper stage would do that orbit raising for them (the non-risky version). The risky part was trying to do an orbit raising with the satellite's onboard fuel, which was the only option after the F9 lost an engine.

The expected outcome (F9 upper stage doing the raising) was considered non-risky, and I'm sure that's the premise the insurance company was operating under when they agreed to insure the satellite.

No, the risky part was trying to raise the orbit using the F9 upper stage after it had burned more fuel than expected due to the failed engine.

Quoth the article:

> Falcon 9 had enough kerosene fuel left over to relight the engine, but the amount of liquid oxygen "was only enough to achieve a roughly 95 percent likelihood of completing the second burn, so Falcon 9 did not attempt a restart,"

I doubt many satellites have enough maneuvering fuel on-board to raise their orbit like that.

You're right. I remember them discussing attempting to raise the orbit with onboard fuel, but I doubt that was possible.

My point was more that, prior to the engine failure, raising the orbit with the second stage was considered non-risky. You're correct that after the failure, raising the orbit with the second stage was risky.

From what I recall, the Orbcomm satellite was supposed to be left in a 350km x 750km orbit by the Falcon 9, and would then use its own reserves to achieve a basically circular orbit, 750km x 750km.

Well, if you could assume that everything will work as expected, you wouldn't need insurance!

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