Interstellar Mission to a Black Hole

Primordial / Small Black Holes in the Solar System

• Some imagine discovering an asteroid‑mass primordial black hole locally, avoiding interstellar travel.
• Multiple comments stress that black holes are not “cosmic vacuums”: a Moon‑mass black hole would gravitationally behave like the Moon; tides and orbits would remain essentially unchanged.
• The danger is from Hawking evaporation, not accretion: very small black holes could undergo runaway evaporation if their Hawking temperature exceeds the cosmic microwave background, potentially ending in intense gamma bursts.
• Detection would be hard:
  • Gravitational effects or microlensing are primary options.
  • Hawking radiation might be detectable only in the final stages.
  • Some argue dust accretion should create faint but detectable X‑rays; others counter that matter densities are too low for significant accretion.
• Ideas surface about black holes captured inside asteroids, making them anomalously dense.

Compact Objects as Megastructures / Sci‑Fi Concepts

• Thought experiments: replacing the Moon with a black hole; building a mini‑Dyson shell around a black hole or neutron star to create a 1g “mini‑world”.
• Limits noted: white dwarfs likely can’t be Moon‑sized; black holes/neutron stars make more sense.
• Stability of Dyson‑like structures is highlighted as a major unsolved issue.

Light Sails, Steering, and Relativistic Hazards

• Clarifications: Breakthrough Starshot–style designs are laser‑driven light sails, not solar‑wind sails; “light sail” is the generic term.
• Stopping/steering:
  • You can tilt a sail to change direction; destination‑star light or a second reflector could in principle brake the craft.
  • Practically, deceleration forces at high speed and large distances are tiny, making orbital insertion extremely challenging; flyby missions seem more realistic.
• Concerns raised about relativistic travel:
  • Interstellar medium impacts at ~0.5c could be catastrophic; “deflectors” à la Star Trek are invoked as a useful fiction.
  • Time dilation at 0.1–0.33c is acknowledged but calculated to be small (percent‑level), not millions of years.

Mission Feasibility: Trajectory Control and Communication

• Several readers argue the key issue—how a ~1 g probe changes trajectory at ~0.3c—is largely hand‑waved in the referenced paper.
• Proposed workarounds:
  • Fire large swarms of probes and rely on statistics (criticized as still inadequate in vast space).
  • Accept unbound flybys and use multiple daughter probes for local experiments and comparative trajectory measurements.
  • Use the sail itself for steering; more speculative ideas include paired probes with springs, which are dismissed as extremely inefficient “rockets” with terrible specific impulse.
• Communication challenges:
  • Skepticism that a 1 g craft can transmit useful data over tens of light‑years; Voyager‑style high‑gain antennas and power sources are far too massive.
  • Suggestions include probe relays, return‑trajectory probes, or nuclear/betavoltaic power, but none are worked out in detail.
  • One commenter notes we also haven’t actually located a nearby black hole; relying purely on statistics is itself a “blocking” issue.

Scientific Payoff vs Alternatives and Priorities

• Some see an interstellar black hole mission as inspirational but question the practical return: “nothing to see” versus strong counter‑claims about rich physics from accretion disks and lensing.
• The Solar Gravitational Lens (SGL) mission and large orbital interferometric telescopes are proposed as more realistic, near‑term “aggressive” projects with clear payoff (e.g., imaging exoplanet surfaces).
• Meta‑discussion laments funding going to AI‑pornbots and near‑term commerce rather than deep‑space infrastructure, though others note that profitable tech tends to get built, whereas pure exploration struggles.
• A few broaden to long‑term human constraints: need to solve launch costs, longevity/aging, and perhaps FTL or cryosleep, or else missions become multi‑generation endeavors.