This document proposes a phased approach to achieving orbital public access by leveraging existing space infrastructure needs. It suggests starting with ISS support flights using a prototype orbital transport vehicle. After 3 years of operational experience, the vehicle could be upgraded to accommodate public passengers at a reasonable safety level. This avoids the high upfront investment required for a standalone tourism venture. The plan outlines configurations for transporting both short-stay tourists and long-stay orbital inhabitants, estimating annual passenger numbers and costs. It concludes that public access to orbit can be economically viable if requirements are incorporated during initial infrastructure development phases.

1. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
A PHASED APPROACH
TO ORBITAL PUBLIC
ACCESS
Mark Hempsell
University of Bristol, UK

2. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
BAD NEWS: THE INVESTMENT TRAP
0 5 10 YEARS 15
5 Annual Revenue
Arbitrary Annual Balance without interest
Money
0 Annual Balance with interest
Annual Spend
-5
ASSUMPTIONS
-10 5 Years before operations
10% per annum interest
-15 50% operational profit
-20
Cumulative Balance
-25

3. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
CERTIFICATION
To carry the public “reasonable” levels of risk need to be
demonstrated.
What is “reasonable”? Approaching 1 in million risk of death
Only achieved by testing and operational experience.
= More cost and more time
Realistic certification makes the investment trap even worse.
The investment would need to be reduced by two orders of
magnitude to break out of the trap.

4. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
SUB-ORBITAL TOURISM
Plus Point:
Vehicle an order of magnitude
lower to acquire than orbital
(still higher than many think!).
But:
(Scaled Composites)
Order of magnitude lower ticket price
Specialist infrastructure – no other sub-orbit applications
The sub-orbital business is on its own

5. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
ORBITAL PUBLIC ACCESS
(Reaction Engines Ltd).
Orbital passenger flights are more marketable – higher
perceived value
But the infrastructure is order of magnitude more expensive
An orbital transport infrastructure can service other markets
and they can cover the acquisition costs

6. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
A CASE STUDY
A Skylon personnel module
(Reaction Engines Ltd).

7. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
PERSONNEL MODULE - INITIAL CONFIGURATION
Hygiene
& ECLSS
Docking port
Kitchen
Cargo space (3 tonnes)
Pilot cabin
21 under floor
triple CTB bays
Ground entry door
4 Passengers
(ejector seats up, supine down)

8. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
15 degree
docking port
alignment
allows rescue
missions
(Reaction Engines Ltd).

9. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
EARLY OPERATIONS
ISS SUPPORT
8 flights a year with half crew rotation with each flight.
Annually deliver 32 crew and 24 tonnes of supplies
Annual budget of around $300 million ($40 million/flight)
+ OTHER MISSIONS
Another 4 flights?

10. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
After 3 years of initial operations
- over 1000 Skylon flights
including around 50 personnel delivery
Ready for certified public access operations.
Needs only the investment to upgrade the Personnel
Module (fast and cheap - no investment trap!)
To get to this point on a standalone basis would
require investment in excess of $20 billion over more
than a decade

11. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
PERSONNEL MODULE - FINAL CONFIGURATION
Hygiene
& ECLSS
Docking port
Kitchen
4 Long stay Passengers
Pilot cabin
21 under floor
triple CTB bays
Ground entry door
16 short stay Passengers

12. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
SHORT STAY LONG STAY
Up to 14 days over 14 days
Cost 1 Cost 6
Supine
Upright
If 100 day tour of duty
4 days up down
4 days up down 6 work days a week
Usable days = 10 Usable days = 79 days
Cost per day 0.1 Cost per day = 0.076

13. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
ASSUMPTIONS ON LONG TERM OPERATIONS
Flights every 14 days to service short stay passengers
Long stay passengers return 7 flights later 98 days
Cost of a personnel launch is $20 million.
Annually 520 passengers - turn over $520 million
BUT WHAT MIX OF SHORT AND LONG TERM

14. 600 Total
500
400 Short stay
Annual For case study
300
Passengers 200 Long stay 104 long stay/year
100 416 short stay/year
0
160
140
Case
120
In Orbit Study For case study
100
Population Total Assumption 28 long stay
80
Long stay
Structure 60 16 short stay
40
20
0
7
6
Seat 5 For case study
Price 4 Long stay = $3.0 M
$M 3 Short stay = $0.5 M
Long stay seat
2
1 Short stay seat
0
0 5 10 15 20
Short Stay (Tourist) Seats per Flight

15. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
CONCLUSIONS
Public access operations to orbit can beat the
investment trap by using the general space
infrastructure.
A first generation reusable launcher can evolve
from ISS support to public access with seat cost
well below $1 million.
However the infrastructure developments must
incorporate the requirements for public access into
the development process.

16. A PHASED APPROACH TO
ORBITAL PUBLIC ACCESS
THANK YOU
(Reaction Engines Ltd)