1. How many sample tubes does the Perseverance rover carry now?
Perseverance went to Mars carrying 43 tubes. Of these, 38 are for samples, and the remaining 5 are called "witness tubes." These witness tubes are used to check if any dirt brought from Earth has mixed with the samples [1]. According to NASA’s sample list, samples have been collected from 30 of the 38 sample tubes [1]. That is about 80% of the sample tubes.
2. What kinds of samples has Perseverance collected on Mars?
Most of the samples are cylindrical cores drilled from rocks. However, samples 17 and 18 were sand formed by weathering, known as regolith. Some of these were placed on the Mars ground in a "sample depot," while the rest remain loaded on the rover [1]. Sample 25 was collected in July 2024 from a rock named "Cheyava Falls," which is shaped like an arrowhead. NASA explains that it has features that could be clues to whether tiny life existed on Mars long ago [2]. They do not claim it is proof of life. It is also possible that chemical changes not involving life could explain these features.
3. Why bring Mars samples to Earth if rovers can study rocks on Mars?
Even on Mars, the rover can study rocks. NASA positions the reason for bringing them back as the first effort to return pieces of another planet to Earth. They state that Earth laboratories can study Mars’s early changes, the possibility of ancient life, and its climate history [2]. The instruments on the rover are limited, while instruments in Earth laboratories are large and precise. The advantages of Earth's instruments are cited as part of the reason the "return" plan has been discussed as worth billions of dollars.
4. What three parts did the Mars Sample Return plan need?
The original plan consisted of three main parts. These were the "Sample Retrieval Lander" (SRL) to land on Mars and collect samples, the "Mars Ascent Vehicle" (MAV) to launch the container from Mars, and the "Earth Return Orbiter" (ERO) to transport it to Earth [3]. To use a delivery analogy, these correspond to the vehicle that goes to the house to pick up the item, the vehicle that leaves the island, and the vehicle that carries it to the mainland. This article focuses only on these three roles, not the detailed mechanics of the vehicles.
5. Why did the Mars Sample Return plan's costs rise and its decision get delayed?
The initial estimate was about 4 to 5 billion dollars over 10 years [3]. However, in May 2023, NASA set up an independent review board. After a 2-month evaluation, they released a report in September with 20 findings and 59 recommendations, expressing concerns about the budget [4]. On April 15, 2024, NASA stated that a budget of 11 billion dollars was too high and a 2040 return was too late. They sought ideas from industry for a return in the 2030s with lower costs and risks, noting costs might range from 8 to 11 billion dollars [5]. Reports say the independent review projected "11 billion dollars and 2040," but this is confirmed only in news reports, not necessarily the review report’s exact numbers [6]. In December 2024, then-NASA Administrator Nelson indicated he would decide early in the new year after reviewing industry proposals [6]. In reality, no decision was made during his term, and the judgment was left to the new administration [7].
6. Why did the Mars Sample Return plan lose funding in January 2026?
NASA’s FY2026 budget proposal showed a policy to end "financially unsustainable programs" including Mars Sample Return [10]. The budget passed in January 2026 also included a joint explanatory statement from Congress that did not support the current MSR program [9]. The program office was also closed [7]. However, this does not mean permanently giving up on bringing back Mars rocks. It means the current plan is cancelled. The 2026 budget includes a new 110 million dollar project called "Mars Future Missions" for future Mars missions, developing technology common to robotic and future human exploration. Sample return is said to be included in this [7]. As of September 29, 2026, the specific path to return Perseverance’s samples has not been re-established. NASA’s MSR page describes the plan in the past tense as "a proposed multi-mission campaign" [11]. However, there are differences in wording between NASA and JPL pages, so it cannot be said that the scientific goal of Mars Sample Return is permanently cancelled.
7. What is Japan's MMX mission to Phobos?
JAXA’s MMX (Martian Moons eXploration) plan is to collect samples from Phobos, a moon of Mars, and bring them to Earth, not from Mars itself. It is scheduled to launch on October 20, 2026, on the H3 rocket No. 10 from the Tanegashima Space Center, with sample return to Earth planned for 2031 [8]. The goal is to collect more than 10 grams of samples from Phobos. However, this is a goal, not a confirmed amount [8]. 10 grams is the weight of 10 one-yen coins. While the amount is small, if samples from a Mars moon are delivered to Earth, they will become material to study the formation of Mars. Launch dates can change, so please read this as a "schedule."
8. How can you look up the latest on Japan's MMX mission yourself?
What you can do today: Check the JAXA MMX Japanese page for the launch date and current status. If the date has moved, you can investigate when and why it changed. Official information: The JAXA MMX site has explanations of Phobos and the probe in Japanese. To follow the MSR history in original sources, the NASA sample list page (in English) is listed in the sources below.