ESA indicates that the first bounce lasted two hours and reached a height of 1 km. With the extremely weak surface gravity and low escape velocity of the body (< 1 m/s), and other publicly available information regarding the comet's mass properties and the landing site location, can we estimate how close the lander came to drifting away into space?
Welcome to Space Exploration Stack Exchange
Space Exploration Stack Exchange is a question and answer site for spacecraft operators, scientists, engineers, and enthusiasts. It's built and run by you as part of the Stack Exchange network of Q&A sites. With your help, we're working together to build a library of detailed answers to every question about space exploration.
We're a little bit different from other sites. Here's how:
Ask questions, get answers, no distractions
This site is all about getting answers. It's not a discussion forum. There's no chit-chat.
Just questions...
...and answers.
up vote
Good answers are voted up and rise to the top.
The best answers show up first so that they are always easy to find.
accept
The person who asked can mark one answer as "accepted".
Accepting doesn't mean it's the best answer, it just means that it worked for the person who asked.
How close was Philae to escape velocity during its first bounce?
up vote
14
down vote
favorite
2 Answers
up vote
4
down vote
accept
It was never close. Rosetta did not have escape velocity when it ejected Philae. So as long as Philae was ejected in the retrograde direction, Philae would not have escape velocity either. After the bounce, Philae would have even less energy due to landing gear attenuation and would therefore be even farther from escaping than it was pre-bounce.
answered Nov 15 '14 at 2:06
Erik
8,02813062
8,02813062
up vote
3
down vote
The new report says Philae was moving at 38 cm/s.
Using Russell's figure of 0.886 m/s as escape velocity, we have 43% of escape velocity.
answered Nov 14 '14 at 13:00
SF.
32.2k8105235
32.2k8105235
Get answers to practical, detailed questions
Focus on questions about an actual problem you have faced. Include details about what you have tried and exactly what you are trying to do.
Ask about...
- Specific aspects of space exploration
- Satellite design and operation
- Systems with potential use in space
- Launch systems, facilities and support infrastructure
- Scientific discoveries made by space probes
- Heliophysics and planetary science
- History of spaceflight
- Trajectory design, orbital and celestial mechanics
- Space policy, legislation, procedures, terminology
- Scientific experiments done in microgravity environment
- Enabling technologies and advances in medical science pertaining to space exploration
Not all questions work well in our format. Avoid questions that are primarily opinion-based, or that are likely to generate discussion rather than answers.
Questions that need improvement may be closed until someone fixes them.
Don't ask about...
- Anything not directly related to space exploration
- Questions that are primarily opinion-based
- Questions with too many possible answers or that would require an extremely long answer
- The study of exosolar objects, except as they relate to space travel
- Physical sciences, such as geology, astronomy, cosmology, meteorology, except as they relate to spacecraft and space exploration
- Questions relating to amateur experiments that are extremely dangerous, such as home-brew rocket propellant
WARNING: This community does not condone such experiments as there may be risk to your health (or even risk of death), and they may even be illegal in your jurisdiction. If you are considering making your own rocket propellant/fuel, please DO NOT DO THIS! Rocket propellant is extremely dangerous, and the protection and storage requirements are best left to professionals.
Are you looking for reference materials or other lists of resources? Check out these resources on our meta site:
Resources and references on the topic of space exploration
Collection of space exploration related infographics
Software tools for space exploration available online
Tags make it easy to find interesting questions
All questions are tagged with their subject areas. Each can have up to 5 tags, since a question might be related to several subjects.
Click any tag to see a list of questions with that tag, or go to the tag list to browse for topics that interest you.
How close was Philae to escape velocity during its first bounce?
up vote
14
down vote
ESA indicates that the first bounce lasted two hours and reached a height of 1 km. With the extremely weak surface gravity and low escape velocity of the body (< 1 m/s), and other publicly available information regarding the comet's mass properties and the landing site location, can we estimate how close the lander came to drifting away into space?
asked Nov 13 '14 at 14:50
pericynthion
8,4743150
8,4743150
You earn reputation when people vote on your posts
Your reputation score goes up when others vote up your questions, answers and edits.
+5
question voted up
+10
answer voted up
+15
answer is accepted
+2
edit approved
As you earn reputation, you'll unlock new privileges like the ability to vote, comment, and even edit other people's posts.
| Reputation | Privilege |
|---|---|
| 15 | Vote up |
| 50 | Leave comments |
| 125 | Vote down (costs 1 rep on answers) |
At the highest levels, you'll have access to special moderation tools. You'll be able to work alongside our community moderators to keep the site focused and helpful.
| 500 | Vote to close, reopen, or migrate questions |
|---|---|
| 1000 | Edit other people's posts |
| 2000 | Access to moderation tools |
Improve posts by editing or commenting
Our goal is to have the best answers to every question, so if you see questions or answers that can be improved, you can edit them.
Use edits to fix mistakes, improve formatting, or clarify the meaning of a post.
up vote
9
down vote
It was never close. Rosetta did not have escape velocity when it ejected Philae. So as long as Philae was ejected in the retrograde direction, Philae would not have escape velocity either. After the bounce, Philae would have even less energy due to landing gear attenuation and would therefore be even farther from escaping than it was pre-bounce.
answered Nov 15 '14 at 2:06
Erik
8,02813062
8,02813062
They are that simple. As long as the separation impulse was small -- which it must have been since Rosetta is still captured -- then nothing else matters. The only other thing that I can think of that might cause Philae to escape would be geyser impingement. - Erik Nov 15 '14 at 2:18
Unlock badges for special achievements
Badges are special achievements you earn for participating on the site. They come in three levels: bronze, silver, and gold.
| Student | First question with score of 1 or more |
| Editor | First edit |
| Good Answer | Answer score of 25 or more |
| Civic Duty | Vote 300 or more times |
| Famous Question | Question with 10,000 views |
Sign up to get started
Signing up allows you to:
- Earn reputation when you help others with questions, answers and edits.
- Select favorite tags to customize your home page.
- Claim your first badge: Informed
Looking for more in-depth information on the site? Visit the Help Center
Space Exploration Stack Exchange is part of the Stack Exchange network
Like this site? Stack Exchange is a network of 174 Q&A sites just like it. Check out the full list of sites.
Use comments to ask for more information or clarify a question or answer.
You can always comment on your own questions and answers. Once you earn 50 reputation, you can comment on anybody's post.
Remember: we're all here to learn, so be friendly and helpful!