# Will the Rocket Lab's Electron rocket really be an effective launch system?

Rocket Lab, a company from New Zealand is working on a small rocket (18 m tall, 10 tonnes), for which there are already over 30 launches lined up at US $5M each. From Wikipedia: In July 2014 it was announced that the company is developing a rocket called Electron, a carbon composite rocket with a payload to orbit of 110 kilograms (240 lb) and a projected cost of less than US$5 million per launch. As of July 2014, the first test launch is planned for 2015.

The whole purpose behind this rocket is to be able to place satellites into orbit far more quickly and for a fraction of the cost of conventional rockets. However, is 110 kg to LEO really a beneficial capability?

I would have thought that most satellites would have a far greater mass than that and that any satellite small enough would have very limited functionality.Or will it most likely be used for very small scale projects such as scientific experiments?

As a side question, what is a rocket like this likely to be fuelled by?

It pays to follow up on references that the Wikipedia you quote quotes itself. For example, this article in The New Zealand Herald lists some of the characteristics of the Electron rocket:

• 18 m in length
• 1 m in diameter
• Weighs more than 10 tonnes
• Lift off mass 10,500 kg
• Liquid oxygen and kerosene propellants
• Top speed of 27,500 km/h

Similar article, perhaps even slightly more detailed, appeared in Parabolic Arc. Both include a video in which Peter Beck, CEO and founder of Rocket Lab Ltd. describes its application.

Now, some of what he talks about is of course marketing. At quoted NZ\$5.84 million (currently US\$4.62 million) per launch, and payload of 110 kg to LEO, this puts its cost per kilogram to LEO at nearly exactly US\\$42,000 / kg.

That's 10 times as much as on a Falcon 9 v 1.1, but you get to select your target orbit independently of other, primary payloads on a higher capacity launcher where your satellite might be a second class citizen. So there ought to be market for it, and if they indeed already have over 30 orders lined up, then they obviously made a compelling case for their Electron rocket.

What use could a 110 kg payload be in LEO? Well, that can launch you up to roughly 80 1U CubeSat satellites on a single launcher, provided they'll all be happy in an identical target orbit and don't require too accurate deployment (I guess a simple lightweight piston would do to push them out of payload fairing all at once or in steps / with a timed delay, or perhaps spinning the upper stage and then slowly "unzipping" its payload fairing, there's many possible engineering options here to still keep its weight down and deploy multiple passengers with some required separation). With selection of higher LEO orbits at different inclinations, and/or more elaborate and precise deployment system that can fast reduce effective payload mass to a dozen of such nano-satellites, provided the launcher even is capable of more complex flight profiles required to attain them.

LOX/Kerosene propellants likely means its second stage engine could be restarted, so it can benefit from, say, coasting phase (attains altitude at some fraction of required orbital speed, cuts main engine off, aka MECO, and then coasts to near orbital velocity with the help of good old Newton before restaring the engine for the final orbital insertion burn).

Actually, Parabolic Arc includes more detail:

• Propellant mass: 9,200 kg
• Maximum engine thrust : 146,000 N (14.8 tonnes)
• Engine equivalent power: 530,000 hp
• Nominal orbit: 500 km circular sun synchronous

That it quotes a circular target orbit confirms that the second stage engine is restartable, since you require an additional burn to circularize the orbit after reaching its target apogee (but the rocket might fly higher than that before MECO - Main Engine Cut-Off - and starting the coasting phase).

So if it could launch in slightly higher LEO orbits where satellite orbits aren't expected to decay as fast due to still some atmospheric drag (that decreases with orbital altitude), I guess it could launch a dozen or so small satellites in a satellite constellation and they could be used for communications, or deliver scientific experiments that would usually be done in low orbits (remote sensing, aka Earth observation, ionosphere experiments, microgravity experiments,...), or technological demonstrators (say, various drag augmentation devices or soft intercepts to deorbit orbital debris, aka space junk, in LEO faster). Your pick. The sky, erm, the low Earth orbit is the limit. 110 kg at the time (and that probably doesn't include the weight of the deployment mechanism).

A few comments. What I find interesting about Electron is that it's extremely light for a two stage system (video shows a short second, upper stage and quoted capability requires at a minimum of two stages). Its total dry mass is only 1,190 kg (without the payload mass of 110 kg) which is nothing short of amazing for an all liquid propellants rocket (and LOX is cryogenic) with all its turbo pumps feeding it.

It's probably not very likely that it would set a new record for the highest engine thrust-to-weight ratio, currently held by Falcon's Merlin 1D rocket engine at T/W of 159.9 (440 kg in mass and thrust of 690 kN). If Electron was to beat that, its quoted 146 kN first stage engine shouldn't weigh more than $$146,000\ \mathrm{kg\ m/s^2} / (159.9 \times 9.807\ \mathrm{m/s^2}) = 93.1\ \mathrm{kg}$$. But at such small dry mass of the complete launcher, it can't be many times over that weight either. We shall see.

One other interesting aspect of the launcher is however that, since it's an all liquid propellants turbo fed engine, it doesn't suffer as severe vibration during launch as solid or hybrid engine designs might, where essentially the whole stage (or in case of hybrids the solid part of it) basically acts as a flute when its solid grain pathways expand. This might be useful to more vibration sensitive payloads, or simply improve reliability of the launcher itself.

And also, as Deer Hunter comments, the launcher might be interesting simply because of its origins and in which country its provider is registered. It's usually only possible to launch military or any other classified payloads atop domestically built and operated launch systems to control access to classified information, conceal the purpose of your payload and/or to abide to defense-related articles, cryptography,... export regulations.

Exact use will also depend on launcher's proven reliability and ability of its upper stage to complete precision orbital insertions. So, with no actual flights, this remains yet to be established.

• The main customer for quick launches into the SSO is the military. – Deer Hunter Nov 15 '14 at 13:03

There are a fair number of satellites under 110 kg, however, the cost of launching them at a value so high will likely dissuade potential buyers. From this database, I count 200 satellites that have been launched with a launch mass of less than or equal to 110 kgs. I can't find any that spend that much cash to launch, although there are some who might have.