The Unit That Crossed a Boundary: Mars Climate Orbiter, 1999
The Mars Climate Orbiter, launched in December 1998, was lost during its orbit insertion around Mars in September 1999. The failure was attributed to a unit mismatch between the software systems of Lockheed Martin and NASA's Jet Propulsion Laboratory. This incident highlights the critical importance of ensuring consistent units in engineering and software interfaces.
- ▪The Mars Climate Orbiter was designed to study Mars' atmosphere and serve as a communications relay.
- ▪It was lost due to a software interface error involving a unit mismatch between imperial and metric measurements.
- ▪The spacecraft's trajectory was miscalculated, leading it to enter the Martian atmosphere at an altitude of 57 km instead of the intended 226 km.
DEV.to (Top) files mainly under programming. We currently carry 4,924 of its stories.
Story provenance
Source · retrieval · rights · ranking — open for full record
inspect →
Story provenance
Attribution is not the same as permission. This drawer separates discovery metadata, excerpts, WeSearch-generated summaries, reuse status, and whether the publisher receives the visit. Nothing here claims a legal grant the publisher has not made.
Record
| Original publisher | DEV.to (Top) |
| Canonical URL | https://dev.to/vivian-voss/the-unit-that-crossed-a-boundary-mars-climate-orbiter-1999-14l6 |
| Publication time | Wed, 20 May 2026 07:52:59 +0000 |
| Retrieval time | 2026-05-20T08:05:00.822Z |
| Last seen | 2026-05-20T08:05:00.822Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | chP-Kb5EDMD- |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3841501) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Vivian Voss Posted on May 20 • Originally published at vivianvoss.net The Unit That Crossed a Boundary: Mars Climate Orbiter, 1999 #postmortem #systemdesign #softwareengineering #freebsd Tales from the Bare Metal (4 Part Series) 1 The Backup That Wasn't 2 The Command That Removed Too Much 3 The Regex That Ran Unbounded 4 The Unit That Crossed a Boundary: Mars Climate Orbiter, 1999 Tales from the Bare Metal — Episode 04 23 September 1999.
…
Excerpt limited to ~120 words for fair-use compliance. The full article is at DEV.to (Top).
Discussion
0 commentsMore from DEV.to (Top)
