Question 1

How does Satellite Laser Ranging (SLR) work?

Accepted Answer

As the satellite passes overhead, our stations shine a pulsed laser towards it and detect the beam reflected off the onboard retroreflector. We precisely time the round trip of these pulses and hence can accurately determine the distance.

Our software then determines the satellite’s orbit and propagates it into the future using our state-of-the-art models, this data is then available to the satellite operator via our secure API.

The satellite operator can then be confident where their satellite is and will be, allowing them to save fuel, increase operational uptime, and maximise their investment.

Question 2

What’s the maximum altitude that you can range to?

Accepted Answer

Range is one of the strengths of SLR. With a suitable retroreflector array, laser ranging can be used to support satellites in LEO, MEO, and GEO... and even lunar and deep-space missions.

Laser ranging is routinely performed to retroreflector arrays left on the moon by the Apollo astronauts.

Question 3

Is this dangerous for aircraft?

Accepted Answer

Safety is our number one priority. Although 'high-power', all our lasers are operated safely with multiple secure layers to ensure people on the ground, pilots in the air, and even astronauts in orbit are at no risk at all.

Our robust aircraft detection systems ensure that the beam is shut down when aircraft pass. We are sure to adhere to regulations put in place by civil aviation authorities.

Question 4

I have onboard GNSS, why do I need SLR?

Accepted Answer

Big questions are being raised by the satellite community of the accuracy of onboard GNSS, we are seeing increased GNSS denial/jamming in certain parts of the world, and many of our customers have experienced GNSS module disruption and even failure.

SLR does not require any data or power consumption by the satellite, is an entirely independent verification of orbit position.

SLR also works even when a satellite fails and enables the operator to not contribute to the growing space debris problem.

With SLR real-time tracking data is available on Earth right after observation, so there’s no waiting around for GNSS data to be downlinked and post-processed.

We still like GNSS! And we recommend using both in day-to-day operations, and if you experience issues with GNSS, we’ll be here to help.

Question 5

Is this going to interfere with my satellite’s optical equipment?

Accepted Answer

Even laser beams spread out according to the inverse square law: which means that we detect only a single photon in the returning pulse.

In orbit, our optical power densities are far below the damage threshold and usually below the detectability threshold of on-board instruments.

Our stations operate in a very narrow wavelength band centred in near-infrared on 1064 nm, therefore not readily detectible by silicon sensors and optical comms typically at 1550 nm, with narrow bandpass filters.

For satellites with the most sensitive equipment we can:
  •  Discuss wavelength requirements
  •. Reduce power
  •. Implement Go/No-Go periods
  •. Set incidence angle limits to ensure that ranging never takes place within the field of view of your instruments.

Question 6

We should be making satellites less reflective, aren’t retroreflectors going to contribute to light pollution?

Accepted Answer

Retroreflectors reflect light only in the direction that it came from. The bright streaks that we see in astronomer’s data is due to sunlight reflected by the surface of the satellite. Any sunlight incident on a retroreflector will be sent back towards the Sun, rather than reflected towards Earth - so in fact retroreflectors are reducing the brightness of the satellite.

Trackability vs. dark sky preservation are usually at odds with one another, but SLR offers the possibility to reduce the albedo of the satellite, and have it safely trackable.

Question 7

What type of retroreflector do I need? And how many?

Accepted Answer

This will depend on your satellite's altitude, and precision requirements. We offer products for LEO, MEO and GEO, suitable for a range of platform types.

Typically you may only need one retroreflector, as little as 20 grams! Chat to us about your mission today at info@lumi.space

Frequently asked questions