Case Study: Two Space Tourisms — Auditing New Shepard and Crew Dragon

"Space is only three minutes away — straight up. It is also forty-five minutes away, sideways, and that sideways is the whole story."

Executive Summary

Two real, flying vehicles carry paying passengers off the Earth today, and both are sold as "space tourism": Blue Origin's New Shepard, a suborbital hopper, and SpaceX's Crew Dragon, an orbital spacecraft. They sound like neighbors on a product line — a cheaper trip and a fancier one. They are not. In this case study we audit both with the tools of the book and show that the gulf between them is one of the widest in all of engineering: about a factor of sixty in energy, and — because the rocket equation turns energy into propellant exponentially — the entire difference between a small reusable rocket and an orbital-class launch stack. By the end you will never again confuse "reached space" with "reached orbit."

Skills applied

• Auditing a vehicle by specific energy and delta-v (§39.4; Ch. 3).
• Converting delta-v into a mass ratio and propellant fraction (Ch. 3).
• Relating re-entry heating to entry speed (Ch. 7).
• Separating a real market from an aspirational one, and tiering every number (§39.6).

Background

Both vehicles are real and have flown crews; all figures below are approximate and attributed (Tier 2), rounded for legibility.

The question the audit answers: why are the launcher, the ticket, and the experience so different, when both "go to space"? The answer is not business strategy. It is physics, and we can compute it.

Phase 1: The energy audit

Audit each vehicle by the specific energy — energy per kilogram — its rocket must supply, because that, not the altitude reached, is the true measure of the job.

New Shepard. At its peak speed of $v \approx 1.0\ \text{km/s}$, the specific kinetic energy is $$\tfrac{1}{2}v^2 = \tfrac{1}{2}(1{,}000)^2 = 5\times10^5\ \text{J/kg} = 0.5\ \text{MJ/kg}.$$ (There is also potential energy in climbing to $105\ \text{km}$, roughly $g h \approx 9.81 \times 105{,}000 \approx 1.0\ \text{MJ/kg}$; the total mechanical energy is on the order of $1.5\ \text{MJ/kg}$. Keep the kinetic term for the clean comparison.)

Crew Dragon. At orbital speed $v \approx 7.7\ \text{km/s}$, $$\tfrac{1}{2}v^2 = \tfrac{1}{2}(7{,}700)^2 \approx 2.96\times10^7\ \text{J/kg} \approx 30\ \text{MJ/kg}.$$

The ratio of kinetic energies is $$\frac{30}{0.5} = 60.$$

Orbit demands about sixty times the energy of the hop. That is the first, blunt statement of the gulf — and it is an understatement of the vehicle difference, as Phase 2 shows.

💡 Intuition: New Shepard's passengers go up into space and fall back; Crew Dragon's go sideways fast enough to keep missing the ground — the definition of orbit from Chapter 4. Altitude is cheap; sideways speed is staggeringly expensive. The two vehicles cross the same line in the sky and then do entirely different physics.

Phase 2: The delta-v audit — where 60× becomes a change of species

Energy is what the rocket supplies, but the rocket equation charges for it in delta-v, exponentially. Convert each job to a required mass ratio at a representative $v_e = 3.4\ \text{km/s}$.

New Shepard needs roughly $\Delta v \approx 1.5\ \text{km/s}$ (peak speed plus gravity losses on a vertical climb): $$\frac{m_0}{m_f} = e^{1500/3400} = e^{0.441} \approx 1.55, \quad\text{propellant fraction} \approx 35\%.$$

Crew Dragon's stack needs about $\Delta v \approx 9.4\ \text{km/s}$ to orbit: $$\frac{m_0}{m_f} = e^{9400/3400} = e^{2.76} \approx 15.8, \quad\text{propellant fraction} \approx 94\%.$$

Now the punchline. The energy ratio was 60×, but look what the exponential did to the hardware requirement: a vehicle that is 35% propellant versus one that is 94% propellant. The first can be a stout, reusable single rocket that lands on its legs. The second cannot exist as a single stage at all — it demands a two-stage, ~94%-propellant orbital rocket (a Falcon 9), the escape hatch of staging (Chapter 3, §3.5). The 60× in energy became the entire difference between two classes of machine.

🔧 Engineering Reality: This is why Blue Origin can fly New Shepard's booster back and reuse it with a modest system, while a fully reusable orbital vehicle is a far harder engineering problem that took SpaceX a decade and is only now maturing at Starship scale (Chapter 38). The rocket equation, not ambition or budget, sets which is easy and which is hard.

Phase 3: The re-entry audit — the gulf runs both ways

The energy a rocket spends going up must be shed coming down as heat (Chapter 7) — so the same 60× reappears on re-entry.

New Shepard's capsule falls back from $105\ \text{km}$ at a modest speed (order $1\ \text{km/s}$), sheds its energy gently, and lands under parachutes with a simple thermal design. Crew Dragon returns from orbit at $\sim 7.8\ \text{km/s}$ — Chapter 7's "$7.8\ \text{km/s} \rightarrow$ heat" problem in the flesh — and needs a substantial ablative heat shield to survive the fireball. The kinetic energy to dissipate scales as $v^2$, so the orbital vehicle must reject on the order of tens of times more energy per kilogram than the suborbital one. Reaching orbit and returning from it are both governed by the same gulf.

⚠️ Common Misconception: "Both crossed the Kármán line, so both 'went to space' equally." They crossed the same altitude, yes — but "going to space" and "staying in space" are separated by the 60× of Phase 1 and the change-of-species of Phase 2. A suborbital passenger touches space; an orbital passenger lives in it, circling the planet, and pays for the privilege in energy, propellant, and re-entry heat at every step.

Phase 4: The market audit — real, but tiered

Now audit the business, tiering as we go. Suborbital tickets are reported in the hundreds of thousands of dollars; hundreds of people have flown — a real, if niche, market (Tier 2). Orbital private missions cost tens of millions per seat; a handful of people have flown privately — real, but only for the very wealthy (Tier 2). The physics of Phases 1–3 is exactly why the price gap is so large: orbital flight burns far more propellant, needs an orbital-class rocket, and demands a serious heat shield. The market gap is the physics gap, priced.

The forecasting error to avoid: assuming suborbital progress predicts orbital progress. It does not, because they sit on opposite sides of the exponential. Suborbital tourism scaling to thousands of passengers would tell you almost nothing about when an orbital seat drops from tens of millions to something ordinary — that depends entirely on the cost of orbital-class reusable launch (theme 5), a different and harder variable.

Discussion Questions

1. The energy ratio is 60×, but the propellant-fraction gap is "35% vs 94%." Explain why the second gap is the one that determines the vehicle class, using the shape of the rocket equation.
2. New Shepard's booster is reusable with a modest system; a reusable orbital booster is far harder. Tie the difference to the numbers in Phase 2.
3. Re-entry heating scales as $v^2$. Roughly what factor more energy per kilogram must Crew Dragon's heat shield reject than New Shepard's, and why does that force a different thermal-protection design (Chapter 7)?
4. A journalist writes that "space tourism is booming" and cites both vehicles together. What is misleading about lumping them, and how would you rewrite the sentence to tier the two markets honestly?

Your Turn: Extensions

• Option A (analysis). Redo Phase 2 using a hydrogen upper stage's $v_e = 4.4\ \text{km/s}$ for the orbital case. Does the propellant fraction for orbit drop below 94%? By how much? Does it change the class of vehicle needed?
• Option B (computation). Write a function audit(v_peak, v_e) that returns the specific kinetic energy and the required mass ratio for a given peak/orbital speed and exhaust velocity. Run it (by hand-tracing) for New Shepard ($1{,}000\ \text{m/s}$) and Crew Dragon ($7{,}700\ \text{m/s}$) and reproduce the numbers above. Add an # Expected output: comment.
• Option C (forecast). Suppose orbital-class launch cost falls another 10× (a Starship goal, Tier 3). Argue qualitatively whether that would close the tourism price gap or merely narrow it, and state which physics from this case study would still keep orbital tickets above suborbital ones.

Key Takeaways

1. "Reached space" ≠ "reached orbit." Orbit costs about 60× the specific energy of a suborbital hop — the difference is sideways speed, not altitude.
2. The exponential turns 60× into a change of species. ~35% propellant (a reusable hopper) versus ~94% propellant (an orbital rocket): the rocket equation, not strategy, sets the hardware.
3. The gulf runs both ways. The same factor reappears as re-entry heat; orbital return needs a real heat shield, suborbital return does not.
4. Both markets are real; they are not the same market. Suborbital progress does not forecast orbital progress, because they live on opposite sides of the exponential. Tier them separately.