With everyone at the bottom of this gravity well called Earth, getting anything into space requires a massive amount of effort and energy.
That said, we lucked out!
Earth sits in what you might call a Goldilocks gravity well: deep enough to hold onto an atmosphere and oceans, yet shallow enough that we can climb out of it with rockets. To escape Earth’s pull entirely requires a velocity of about 11.2 km/s, while reaching orbit needs roughly 7.8 km/s. That is equivalent to burning through nine-tenths of your rocket mass in propellant just to reach an altitude of a few hundred kilometers. That is a brutally steep climb and it pushes our launch systems to the theoretical limit of what chemical energy can supply.
Had Earth been a bit larger its escape velocity would exceed what even the most efficient chemical propellants (liquid hydrogen and oxygen) can generate enough delta-v to break free with useful payloads. A world only slightly smaller, by contrast, would lose its atmosphere and water to space well before any species can dream of building rockets. We happen to live on the kind of planet that is just massive enough to live on and just small enough to leave. A cosmic sweet spot that makes spaceflight hard, but possible.
Payload fraction
One of the most important metrics for a rocket is the payload fraction, the amount of useful mass that can be brought to space. This efficiency indicator is the hard cap driven by Earth's gravity well and it shows how much rocket and fuel you need to get a kilogram of useful mass to the right orbit. That fraction drops the closer you get to Earth escape and several of the rockets currently operating can't even make it to higher energy orbits.
The SpaceX workhorse Falcon9 has a 3.2% fraction to LEO, dropping to 0.6% for Earth escape. The Falcon Heavy has increased capacity at 4.2% to LEO and 1.2% to escape, while Starship is currently projected to achieve about 2% to LEO. While that last launch brings a lot more mass to LEO, it can't get to Earth escape.
Other commercial rockets achieve broadly similar ranges, which has kept the cost of launching stuff to orbit high and climbing in the last decade.
Launch cost
This graph is probably the most misunderstood and misquoted representation of the space market in the last 2 decades. It shows this compelling downward slope on launch cost, which does not track with reality at all:
If you talk to anyone actually buying launches today, it looks like this:
This launch cost narrative has become so pervasive that it shows up pretty much everywhere. This is where the narrative breaks down:
- We all pay the SpaceX price, not the SpaceX cost. As the effective monopolist providing launch services, they get to decide what that price level is and they increase it every year.
- 'Nobody' buys a full rocket, we all buy seats on rideshares. 95+% of satellites launched in the last decade (excluding SpaceX Starlink) are smallsats that only weigh up to a couple hundred kg.
- Launches are half empty. With a mass-volume mismatch, sharing the launch fairing with other payloads and needing to survive the launch environment, mass utilization rates sit well below 50%.
Surviving launch as an asteroid miner
Once you've paid the launch tax to SpaceX or some other provider, you need to figure out how to design your spacecraft to survive the launch environment. Those first 10 minutes after launch are brutal, which is something we need to test extensively beforehand before we're even allowed to fly our spacecraft.
With launch about a year out as we write this, we're currently testing all of our components and subsystems in increasing levels of fidelity. The video shown at the top of this post shows one of the most fragile parts of our spacecraft, our high gain antenna for radio communications.
This antenna needs to be as light as possible, alongside everything else on the spacecraft because every kilogram of launch is so expensive. It also sits at the far end of our spacecraft compared to the mounting plate that connects to the rocket.
These goals of high performance, low mass and structural stability are in natural tension, requiring both extensive simulations as well as extensive tests.
We're grateful about living at the bottom of that goldilocks gravity well, which allows us to work on problems like this at all because launch is at least possible. For now it remains technically challenging and ever more expensive.