NASA releases Hubble image taken in new pointing mode

Original Article ↗ Hacker News Discussion ↗

Hubble’s new one‑gyro pointing mode

  • NASA now runs Hubble with a single gyro to conserve remaining units.
  • On-target stability is described as nearly comparable to three-gyro mode.
  • Tradeoffs: ~12% efficiency loss from longer slews and guide-star acquisition, restricted sky coverage at any moment, and ~20–25% overall productivity loss vs. three-gyro operations.
  • Hubble can no longer track fast-moving near-Earth targets (e.g., objects closer than Mars’ orbit) and is less flexible for sudden “targets of opportunity.”

Longevity and hardware

  • Hubble launched 34 years ago with a 15‑year design life; its continued operation is widely seen as impressive.
  • Its onboard computer is i486-class, prompting nostalgia and discussion of how modest compute is enough for tightly designed control loops.
  • Some commenters lament that we patch a decades-old telescope instead of launching new Hubble-class successors every decade; others see the long life as a success against “throwaway culture.”

Gyroscopes, control, and sensors

  • Hubble has six gyros; multiple sets have failed over the years, with replacements during Shuttle servicing missions.
  • Two currently work; one is now held in reserve while single‑gyro mode runs.
  • Discussion clarifies:
    • Gyros are sensors; reaction wheels (not control-moment gyros) actually rotate Hubble.
    • The one‑gyro mode relies heavily on star trackers and magnetometers with Kalman filtering for sensor fusion.
  • MEMS phone-style gyros are noted as far less precise than Hubble’s gas‑bearing units; newer missions favor more reliable hemispherical resonator gyros.

Servicing Hubble and private missions

  • Several comments debate potential Dragon or Starship servicing.
  • Issues raised: lack of an airlock on Dragon (requiring full-capsule depressurization), contamination risks to optics from venting and thrusters, and grappling challenges without Shuttle’s arm.
  • A privately funded mission has reportedly been offered and declined; NASA is said to judge the risk of harming a still‑functional Hubble as outweighing potential gains.

NASA budget, efficiency, and politics

  • Many see NASA as underfunded relative to defense and large tech firms, noting its ~$25B budget and ~18k staff.
  • Others argue NASA’s crewed programs (e.g., SLS/Orion) are extremely costly and shaped by congressional “pork-barrel” mandates and cost‑plus contracting.
  • There is disagreement over how to measure “efficiency,” but broad frustration with political constraints is evident.

Broader astronomy context

  • Hubble’s original mirror flaw and later fix are recalled; its arc from “failure” to iconic success is emphasized.
  • Commenters mention JWST and the upcoming Nancy Grace Roman Space Telescope, noting differing wavelength coverage and that no true like‑for‑like Hubble replacement exists yet.
  • Some express disappointment that many high-end space telescopes look downwards (military) rather than outwards (science).