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Didn't SpaceX just lose a rocket in similar fashion? What's the difference?

by ijidak 2y ago

deleted 2y ago
[deleted]
JumpCrisscross 2y ago
> Didn't SpaceX just lose a rocket in similar fashion? No. China's debris are in orbit and will remain there for "decades" [1]. This is because its rocket exploded. The errant Falcon 9 had engine trouble but retained structural integrity [2]. That allowed SpaceX to "make contact with the satellites in order to send early burn commands" so that they "re-enter Earth’s atmosphere," thereby no longer posing "a threat to other satellites in orbit or to public safety." [1] https://x.com/US_SpaceCom/status/1821615199230816555 https://x.com/US_SpaceCom/status/1821615199230816555 [2] https://www.spacex.com/launches/mission/?missionId=sl-9-3 https://www.spacex.com/launches/mission/?missionId=sl-9-3
- ortusdux 2y ago
  A key element are the altitudes. SpaceX, out of an abundance of caution, inserts their starlink satellites low enough that any non-functional units or debris will deorbit in a matter of months. If they pass testing, they self-boost to their operational heights of 350 miles or so. At this height they still need to occasionally re-boost themselves. This launch from China inserted the 18 satellites directly into a 500 mile orbit, presumably because they didn't want to fuss with boosting.
  - JumpCrisscross 2y ago
    Did not know. Thank you. This sounds partly a result of their engines. Low orbits require more precision. Liquid-fuelled engines are good at that. The Long March 6A is solid fuelled.
    - wmf 2y ago
      The Long March 6A second stage that failed here is liquid-fueled.
      - JumpCrisscross 2y ago
        First stage sets the gross orbital parameters. You overshoot with solid.
        wmf 2y ago
        I've seen no evidence that there was any overshoot here. It sounds like the satellites were inserted into the desired orbit and then the second stage broke up.
        JumpCrisscross 2y ago
        > no evidence that there was any overshoot here. It sounds like the satellites were inserted into the desired orbit and then the second stage broke up Does Long March 6A's first stage not burn out, past no return, higher than Falcon 9? For a solid-fuel rocket, burnout altitude almost defines payload altitude. (Long March 6A's liquid-fuelled second stage adjusts for that.) That isn't so for a throttlable engine. Given a solid-fuelled first stage, a competent engineer would add a margin of safety to the energy budget.

Didn't SpaceX just lose a rocket in similar fashion? What's the difference?

by ijidak 2y ago

Didn't SpaceX just lose a rocket in similar fashion? What's the difference?

deleted 2y ago

[deleted]

JumpCrisscross 2y ago

> Didn't SpaceX just lose a rocket in similar fashion? No. China's debris are in orbit and will remain there for "decades" [1]. This is because its rocket exploded. The errant Falcon 9 had engine trouble but retained structural integrity [2]. That allowed SpaceX to "make contact with the satellites in order to send early burn commands" so that they "re-enter Earth’s atmosphere," thereby no longer posing "a threat to other satellites in orbit or to public safety." [1] https://x.com/US_SpaceCom/status/1821615199230816555 https://x.com/US_SpaceCom/status/1821615199230816555 [2] https://www.spacex.com/launches/mission/?missionId=sl-9-3 https://www.spacex.com/launches/mission/?missionId=sl-9-3

ortusdux 2y ago
A key element are the altitudes. SpaceX, out of an abundance of caution, inserts their starlink satellites low enough that any non-functional units or debris will deorbit in a matter of months. If they pass testing, they self-boost to their operational heights of 350 miles or so. At this height they still need to occasionally re-boost themselves. This launch from China inserted the 18 satellites directly into a 500 mile orbit, presumably because they didn't want to fuss with boosting.
- JumpCrisscross 2y ago
  Did not know. Thank you. This sounds partly a result of their engines. Low orbits require more precision. Liquid-fuelled engines are good at that. The Long March 6A is solid fuelled.
  - wmf 2y ago
    The Long March 6A second stage that failed here is liquid-fueled.
    - JumpCrisscross 2y ago
      First stage sets the gross orbital parameters. You overshoot with solid.
      - wmf 2y ago
        I've seen no evidence that there was any overshoot here. It sounds like the satellites were inserted into the desired orbit and then the second stage broke up.
        JumpCrisscross 2y ago
        > no evidence that there was any overshoot here. It sounds like the satellites were inserted into the desired orbit and then the second stage broke up Does Long March 6A's first stage not burn out, past no return, higher than Falcon 9? For a solid-fuel rocket, burnout altitude almost defines payload altitude. (Long March 6A's liquid-fuelled second stage adjusts for that.) That isn't so for a throttlable engine. Given a solid-fuelled first stage, a competent engineer would add a margin of safety to the energy budget.