It’s the future…
…and the past.
Space Mirrors will place a four-kilometre reflector one light-year from the Sun, aimed precisely at Earth. Light leaving Earth today reaches it next year and returns the year after. Point a telescope at the mirror and you see Earth as it was two years ago. It's the future, and the past.
The programme
Space Mirrors is a single, permanent piece of infrastructure: a flat, segmented reflector four kilometres across, delivered to a point one light‑year from the Sun and held perpendicular to the Earth line to within a fraction of a nanoradian.
It requires no new physics. Light from Earth travels to the mirror in one year and returns in one more. Any sufficiently large telescope pointed at the mirror sees the Earth of two years ago, in daylight and in darkness, continuously, for as long as the mirror exists.
The mirror does not stop. It continues outward at a fifth of the speed of light, and the record it returns grows longer every year.
How it works
Stage 01 · Launch
The reflective membrane is one gram per square metre. Folded on a modified Miura pattern around a central truss, the entire four‑kilometre aperture stows inside a standard nine‑metre fairing with room for the deployment mechanism and a very small amount of contingency.
Stage 02 · Deployment
At the Sun–Earth L2 point the truss extends and the membrane unfolds outward ring by ring, from the centre to the fortieth, over eleven days. Each hexagonal segment is fifty‑two metres flat‑to‑flat and carries its own actuator. Together they form a single flat surface with a figure error smaller than the wavelength of light.
Stage 03 · Photon drive
A phased laser array in the Atacama illuminates the fully deployed reflector. Every photon that strikes it and returns imparts twice its momentum. Over fourteen months of continuous illumination the mirror reaches a fifth of the speed of light and is released onto its final heading. It is not decelerated. It does not need to be.
Stage 04 · Reflection
Light leaving Earth reaches the mirror after one year and is returned along the same line. The Lookback Array, a twelve‑million‑kilometre synthetic aperture in heliocentric orbit, resolves the returned image to one metre on the ground. The Earth it shows is the Earth of two years ago, continuously, from first light onward.
Specifications
All figures are for the flagship unit at Reflection Point One. Figures marked with an asterisk increase over the life of the mission.
| Aperture | 4.00 km, flat |
|---|---|
| Segments | 4,921 hexagonal, 40 rings, 52 m flat‑to‑flat |
| Reflective area | 12.57 km² |
| Membrane | Multilayer dielectric on polyimide, 1 g/m² |
| Reflectivity | 99.95 % at 550 nm |
| Surface figure | λ/20 RMS, actively maintained |
| Total mass | 41 t including truss, actuators and bus |
| Stowed envelope | 8.4 m × 16.9 m |
| Station distance | 1.000 ly · 63,241 AU * |
| Lookback | 2.000 yr * |
| Lookback growth | 0.40 yr per year |
| Cruise velocity | 0.20 c |
| Playback rate | 0.667× (z = 0.50) |
| Pointing tolerance | 0.67 nrad |
| Pointing authority | 4,921 segment actuators, 3 reaction wheels |
| Operating temperature | 3 K, ambient |
| Power | 20 W housekeeping, radioisotope |
| Ground segment | Lookback Array, 12,000,000 km synthetic aperture, 2,048 elements |
| Ground resolution | 1.0 m at nadir |
| Design life | Indefinite |
Lookback catalog
Lookback is twice the station distance divided by the speed of light. Every unit uses the same reflector; only the distance differs.
SM‑H
1 light‑hour · 7.2 AU
2hours
Stationed near the orbit of Saturn. Instant replay for the entire planet. Suitable for organisations that need to confirm what just happened.
Service from 2028
SM‑D
1 light‑day · 173 AU
2days
Beyond Voyager 1. A two‑day lookback covers most things people wish they had paid attention to at the time.
Service from 2029
Flagship
SM‑1
1 light‑year · 63,241 AU
2years
The flagship unit at Reflection Point One. Two full years of Earth, continuously available, with lookback growing by 0.4 years for every year of service.
Service from 2033
SM‑50
50 light‑years
100years
A full century. The unit reaches station in 2277 and returns the years 2177 onward. Reservations are transferable to descendants.
Service from 2277
What this enables
Every event after first light is observable on demand, from orbit, at one‑metre resolution. Disagreements about what happened become observations of what happened.
Continuous full‑disc imagery of ice, forest, coastline and cloud with no gaps in coverage and no dependence on the weather at the observatory.
Whatever you missed two years ago is still arriving. The mirror returns it in order, at 0.667× speed, in a slightly warmer tone.
Records held on Earth can be edited. Photons in transit cannot. Space Mirrors provides a copy of the recent past that nobody has had access to yet.
Compare any location against itself two years earlier, at the same hour, under the same light, without ever having planned to.
For the first time, the whole planet will be able to see itself from one light‑year away. We anticipate this will be clarifying.
Programme
Q3 2027
SM‑1 departs on a single heavy‑lift vehicle and is delivered to a transfer orbit toward Sun–Earth L2.
Q4 2027
Truss extension and eleven‑day membrane unfold. Segment actuators bring the surface to λ/20.
2028
Fourteen months of illumination from the Atacama array. Cruise velocity of 0.20 c reached and heading fixed.
2029
Lookback service begins during cruise at a delay of several weeks, increasing continuously.
2032
The mirror passes one light‑year from the Sun. Lookback reaches two full years.
2033 →
Lookback grows by 0.4 years per year. The mirror is not scheduled to stop.
Questions
Yes. A curved mirror would return a smaller, inverted Earth. We considered it.
No. A mirror can only return light that reaches it after deployment. Space Mirrors reflects the future's past, not the past's past. Service begins in 2029 and the archive grows from there.
The mirror recedes at a fifth of the speed of light. Light is Doppler‑shifted once on arrival and once on departure, so the returned image runs at 0.667× real time and is redshifted by a factor of 1.5. Most customers describe the effect as calming.
The surface is held to 0.67 nanoradians by 4,921 independent actuators. If it were to point the wrong way, somebody else would see our past. We consider this acceptable.
Yes. Reserve a viewing window today and your window opens in two years, showing today.
There is no end of the mission. The mirror continues outward and the lookback grows by 0.4 years per year. In 2133 it will return the year 2091. It will still be pointed at us.
No. Telescopes look at other places.
Reservations
Windows are allocated on the SM‑1 unit in order of reservation. Your window opens exactly two years after the date of reservation and shows the date of reservation.
Reservation confirmed
SM‑1 / 000000
Your window opens on , showing .
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