Sending a probe to Mars generally takes much less energy than sending one to Mercury, even though Mercury is closer to the Sun. This seems counterintuitive, but it comes down to orbital mechanics and velocity changes (Δv).
🚀 Key idea: It’s about speed, not just distance
When launching from Earth, your spacecraft is already moving around the Sun at about 30 km/s. The challenge is changing that motion to match another planet’s orbit.
To reach Mars (farther from the Sun): you need to slow down slightly relative to the Sun so your orbit expands outward.
To reach Mercury (closer to the Sun): you must lose a lot of orbital energy, which means slowing down a lot relative to the Sun.
🔴 Mars: Lower energy target
Mars orbits at ~1.5 AU (astronomical units).
A typical trajectory (Hohmann transfer) requires a moderate Δv.
Once there, orbit insertion or landing is relatively manageable.
✅ Result: Lower overall energy requirement compared to Mercury.
🔥 Mercury: Much harder energetically
Mercury orbits at ~0.39 AU.
The Sun’s gravity is much stronger there.
To enter orbit around Mercury, a probe must shed a huge amount of orbital speed.
Why this is difficult:
You’re not just “falling inward”—you must cancel Earth’s fast sideways motion around the Sun.
That requires large Δv or complex trajectories.
Practical consequence:
Missions use multiple gravity assists (e.g., Venus, Earth) to gradually reduce energy.
Example: NASA’s MESSENGER and ESA/JAXA’s BepiColombo took many flybys and years to get there.
❗ Without gravity assists, going to Mercury would require far more fuel than most rockets can carry.
⚖️ Rough comparison
Destination
Relative energy (Δv)
Difficulty
Mars
Moderate
Easier
Mercury
High
Much harder
🧠 Bottom line
Even though Mercury is closer, it takes significantly more energy to send a probe there than to Mars, because you must fight the Sun’s gravity and remove a large amount of orbital speed.
If you want, I can sketch the trajectories or show approximate Δv values to make the comparison even clearer.
A tidally locked pulsar planet is a fascinating idea, and you’re right to zero in on the dark side as the only plausible refuge. The key insight is this:
If a pulsar planet is tidally locked, the night side becomes the only region shielded from the lethal particle wind and X‑ray flux.
That doesn’t automatically make it habitable, but it does carve out a narrow, physically interesting niche where habitability isn’t absurd.
Let’s unpack what that world would actually be like.
🌑 1. Why the dark side is the only possible sanctuary
Pulsars emit:
Hard X‑rays
Gamma rays
Relativistic particle winds
Magnetospheric radiation
The day side of a tidally locked planet would be:
Sterilized
Atmosphere‑stripped
Heated by high‑energy radiation, not visible light
But the night side is shielded by the bulk of the planet. That’s the only place where:
Molecules can survive
Atmospheres can persist
Liquid water is even conceivable
This is similar to the “terminator habitability” idea for red‑dwarf planets, but far more extreme.
🛡️ 2. What the planet would need to protect the night side
A pulsar planet would require three layers of defense:
A. A very thick atmosphere
Models suggest 10⁵–10⁶× Earth’s atmospheric pressure.
That’s like living under the pressure of the deep ocean.
Such an atmosphere:
Redistributes heat
Absorbs high‑energy particles
Prevents atmospheric escape
Blocks X‑rays and gamma rays
B. A strong magnetic field
This is tricky.
A tidally locked planet rotates slowly, which weakens the dynamo.
But if the planet is:
Massive (super‑Earth)
Partially molten
Rich in conductive materials
…it could still maintain a magnetic field strong enough to deflect some of the pulsar wind.
C. A heat source
The night side receives no starlight.
So it needs:
Geothermal heat
Atmospheric heat transport
Possibly tidal heating if other planets are present
Without these, the dark side freezes solid.
🌡️ 3. What the dark side would feel like
Imagine a world where:
The sky is pitch black—no stars, no twilight
The atmosphere is dense and warm, like a deep‑sea trench
Winds constantly blow from the irradiated day side
The ground may be carbon‑rich or diamond‑like
The only illumination is faint auroral glow from charged particles
It’s not Earthlike, but it’s not impossible.
🧬 4. Could life exist there?
If life exists, it would be:
Subsurface or deep‑atmosphere
Shielded from radiation
Chemically driven (chemosynthesis), not photosynthesis
Adapted to high pressure and low light
Think of something between:
Earth’s deep‑ocean vent ecosystems
Titan’s atmospheric chemistry
Europa‑style subsurface life
The dark side could host liquid water oceans if the atmosphere is thick enough to trap heat.
🔭 5. The non‑obvious twist: the terminator zone might be the sweet spot
The boundary between day and night—the “eternal twilight ring”—could be the most stable region:
Warm enough from atmospheric circulation
Shielded enough from direct radiation
Constant winds and cloud cover
Potentially Earthlike temperatures
This is the same logic used for M‑dwarf tidally locked planets, but with much harsher radiation physics.
🧠 6. The deeper physical question
Your idea touches a subtle point: Habitability around pulsars is not about light, but about shielding and heat transport.
A tidally locked configuration helps because it creates a permanent refuge.
It’s one of the few geometries where a pulsar planet could maintain a stable, long‑term habitable region.
If you want, we can push this further:
Model the atmospheric circulation on such a world
Estimate the temperature gradient between day and night
Explore what chemistry life would use without sunlight
Compare this to the PSR B1257+12 planets specifically
Consider whether a tidally locked configuration is dynamically stable around a millisecond pulsar
The company began as a partnership in 1974 between Harry Garland and Roger Melen, two Stanford Ph.D. students. The company was named for their residence at Stanford University (Crothers Memorial, a Stanford dormitory reserved for engineering graduate students). Cromemco was incorporated in 1976 and their first products were the Cromemco Cyclops digital camera, and the Cromemco Dazzler color graphics interface - both groundbreaking at the time - before they moved on to making computer systems.
In December 1981, Inc. magazine named Cromemco in the top ten fastest-growing privately held companies in the U.S.[1] In 1987, it was acquired by Dynatech Corporation of Boston.
Southwest Technical Products Corporation, or SWTPC, was an American producer of electronic kits, and later complete computer systems. It was incorporated in 1967 in San Antonio, Texas, succeeding the Daniel E. Meyer Company. In 1990, SWTPC became Point Systems, before ceasing a few years later.
Shugart Associates (later Shugart Corporation) was a computer peripheral manufacturer that dominated the floppy disk drive market in the late 1970s and is famous for introducing the 5+1⁄4-inch "Minifloppy" floppy disk drive. In 1979 it was one of the first companies to introduce a hard disk drive form factor compatible with a floppy disk drive, the SA1000 form factor compatible with the 8-inch floppy drive form factor.
Founded in 1973, Shugart Associates was purchased in 1977 by Xerox, which then exited the business in 1985 and 1986,[1] selling the brand name and the 8-inch floppy product line (in March 1986) to Narlinger Group,[2] which ultimately ceased operations circa 1991.
SAGE Computer Technology was a computer company based in Reno, Nevada, United States. It was founded in 1981 by Rod Coleman, Bill Bonham and Bob Needham; it went through several name changes. The change from Sage computer came about when "Sage Software" in Maryland demanded cessation of use of the name Sage in the computer segment.[1]
SAGE Computer Technology
- created the Sage II and Sage IV computers based on the Motorola 68000 microprocessor.
SAGE Computer
Stride Micro
MicroSage Computer Systems (a wholly owned subsidiary, 1987)
- created the Stride 420, Stride 440, Stride 460 (VME),[2] Stride 660 and Stride 740 computers.
Percom Data Corporation was an early microcomputer company formed in 1976 to sell peripherals into the emerging microcomputer market. They are best known for their floppy disk systems, first for S-100 machines, and the later for other platforms like the TRS-80 and Atari 8-bit computers.[2] The company was purchased by Esprit Systems in 1984.
Anderson Jacobson, also known for a time as CXR Anderson Jacobson and today as CXR Networks, is a vendor of communications equipment.
Anderson Jacobson formed in California in 1967 as a spin-off from SRI International (then the Stanford Research Institute),[1] to commercialize its acoustic coupling modem designs. In the 1970s and 1980s, the company manufactured modems, some intended for consumers.[2] The introduction of the Hayes Smartmodem in 1981 led to many early vendors, including Anderson Jacobson, being forced from the market as newer companies entered at ever lower price points.
The company was acquired by CXR Telecom in 1988,[1][3] at which time The Times was following Anderson Jacobson's earnings reports.[4] The flow of new products continued.[5]
Today the company is a privately owned communication equipment vendor supplying products to Telecom Carriers, Service Providers, and the Defense, Transport and Utility markets. The company is headquartered in Abondant, France.[6][7]
Mountain Computer, Inc. (also known as Mountain Hardware[1]) was a privately held[2] American computer peripheral manufacturer active as an independent company from 1977 to 1988. In its early years, the company chiefly developed products for the Apple II, including sound synthesizers, samplers, and hard disk and tape drives. Mountain also produced floppy disk duplicators for enterprise use. In the mid-1980s Mountain pivoted to focusing on products for the IBM Personal Computer and compatibles. In late 1988, the company was acquired by Nakamichi.
Kildall information plaque Pacific Grove, California
In 1974 in Pacific Grove, California, Kildall demonstrated the first working prototype of CP/M, which would later become the dominant operating system for microcomputers for a time.[8] Together with his invention of the BIOS (Basic Input Output System), his operating system allowed a microprocessor-based computer to communicate with disk storage.[9] Kildall was among the earliest individuals to recognize microprocessors as fully capable computers.[6] During the 1980s, Kildall also appeared on PBS as co-host of Computer Chronicles, a weekly informational program that discussed the latest developments in personal computing.
Several notable employees worked at Digital Research, some of which later made important contributions to the IT industry, such as:
Percom Data Corporation was an early microcomputer company formed in 1976 to sell peripherals into the emerging microcomputer market. They are best known for their floppy disk systems, first for S-100 machines, and the later for other platforms like the TRS-80 and Atari 8-bit computers.[2] The company was purchased by Esprit Systems in 1984.
The VAX‑11/780 is one of the most important minicomputers in computing history. Introduced by Digital Equipment Corporation (DEC) in 1977, it effectively defined what people meant by “VAX” and helped shape modern computer architecture.
Here’s a clear overview, from context to technical details and impact.
What “VAX‑11/780” Means
VAX = Virtual Address eXtension
11 = marketing continuity with DEC’s earlier PDP‑11 line
780 = roughly “0.78 MIPS” (a performance rating by DEC’s internal metric)
Despite the name, it was not a PDP‑11; it was a completely new 32‑bit architecture.
Why It Mattered
The VAX‑11/780 was revolutionary because it combined:
True 32‑bit computing
Virtual memory built into the architecture
A rich, expressive instruction set designed to support high‑level languages
For universities, research labs, and businesses, it became the machine of the late 1970s and 1980s.
Architecture Highlights
Word Size & Memory
32‑bit architecture
Virtual address space: up to 4 GB (huge for the time)
Demand‑paged virtual memory with hardware support
Instruction Set (CISC)
Classic CISC design:
Hundreds of instructions
Variable‑length instructions
Memory‑to‑memory operations
Designed to make compiled code compact and expressive
Excellent support for:
Procedure calls
Stack frames
Data structures
This made VAX machines very friendly to languages like C, FORTRAN, Pascal, and later Ada.
Performance
Roughly 1 MIPS (million instructions per second)
Slower in raw speed than later RISC machines, but very powerful for its era
Performance was respectable because much work could be done in fewer instructions
Operating Systems
The VAX‑11/780 ran several influential operating systems:
VMS (later OpenVMS) – DEC’s flagship OS
Highly reliable
Strong security model
Still in use today (on modern hardware)
BSD UNIX
The VAX became the platform for early BSD development
Many UNIX features (job control, TCP/IP stack refinements) matured on VAX systems
If you’ve used modern UNIX or Linux, you’re indirectly benefiting from VAX‑era work.
Hardware Form
Typically filled one or more refrigerator‑sized cabinets
Used TTL logic (no microprocessor yet)
Consumed significant power and required cooling
Peripheral ecosystem included:
Disk drives (RP06, RM03, etc.)
Tape drives
Serial terminals (VT100 was iconic)
Historical Impact
The VAX‑11/780:
Dominated academic computing in the late ’70s and ’80s
Became the reference machine for operating‑system research
Influenced later CPU and OS design—even as RISC later rejected many CISC ideas
Marked the high point of minicomputers before workstations and PCs took over
A famous saying from the era:
“If you haven’t used a VAX, you don’t know what a real computer is.”
Decline
In the late 1980s–1990s, RISC processors (SPARC, MIPS, PA‑RISC) surpassed VAX in performance per watt
DEC eventually replaced VAX with Alpha
Still, VAX systems lingered in production for decades due to VMS reliability
If you’d like, I can:
Compare the VAX‑11/780 to the PDP‑11 or early RISC machines
Explain why VAX CISC lost to RISC despite its elegance
Talk about VMS vs UNIX on VAX
Or connect VAX ideas to modern CPUs and operating systems
